Week to Decade Converter
Convert weeks to decades with our free online time converter.
Quick Answer
1 Week = 0.001917 decades
Formula: Week × conversion factor = Decade
Use the calculator below for instant, accurate conversions.
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Week to Decade Calculator
How to Use the Week to Decade Calculator:
- Enter the value you want to convert in the 'From' field (Week).
- The converted value in Decade will appear automatically in the 'To' field.
- Use the dropdown menus to select different units within the Time category.
- Click the swap button (⇌) to reverse the conversion direction.
How to Convert Week to Decade: Step-by-Step Guide
Converting Week to Decade involves multiplying the value by a specific conversion factor, as shown in the formula below.
Formula:
1 Week = 0.00191653 decadesExample Calculation:
Convert 60 weeks: 60 × 0.00191653 = 0.114992 decades
Disclaimer: For Reference Only
These conversion results are provided for informational purposes only. While we strive for accuracy, we make no guarantees regarding the precision of these results, especially for conversions involving extremely large or small numbers which may be subject to the inherent limitations of standard computer floating-point arithmetic.
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View all Time conversions →What is a Week and a Decade?
The week (symbol: wk or w) is a unit of time equal to 7 days, 168 hours, or 10,080 minutes.
Official status: The week is not an SI unit, but it is accepted for use with the SI due to its universal cultural importance. The SI base unit of time is the second, and the day is the fundamental accepted non-SI unit.
Standard conversions:
- 1 week = 7 days (exact)
- 1 week = 168 hours (7 × 24)
- 1 week = 10,080 minutes (7 × 24 × 60)
- 1 week = 604,800 seconds (7 × 24 × 60 × 60)
- 1 year ≈ 52.14 weeks (365 ÷ 7)
- 1 month ≈ 4.35 weeks (30 ÷ 7)
The 7-day structure: The week consists of seven consecutive days, typically organized as:
International (Monday-first) convention:
- Monday (Moon's day) - Start of work week
- Tuesday (Tiw's day, Norse god of war)
- Wednesday (Woden's day, Odin)
- Thursday (Thor's day, god of thunder)
- Friday (Frigg's day, goddess of love)
- Saturday (Saturn's day)
- Sunday (Sun's day) - Traditional day of rest
US (Sunday-first) convention:
- Sunday considered first day of the week on US calendars
- Work week runs Monday-Friday
- Weekend is Saturday-Sunday
ISO 8601 standard:
- Monday is officially day 1 of the week
- Sunday is day 7
- Week numbering: Week 1 contains first Thursday of year
Workweek vs. weekend:
- Workweek/weekdays: Monday-Friday (5 days) in Western tradition
- Weekend: Saturday-Sunday (2 days) in Western tradition
- Varies by culture: Friday-Saturday in Muslim countries, Sunday only historically
Why 7 days, not 5, 8, or 10? Unlike the day (Earth rotation) or year (orbital period), the week has no astronomical basis. It's purely a human cultural construct that gained universal adoption through:
- Ancient Babylonian astronomy (7 visible celestial bodies)
- Jewish religious tradition (Genesis creation, Sabbath commandment)
- Christian adoption and spread (Sunday worship)
- Islamic adoption (Friday as holy day)
- Roman Empire standardization (321 CE Constantine decree)
- Deep cultural entrenchment making change impractical
A decade is a unit of time equal to 10 consecutive years. The word derives from Ancient Greek "dekas" (δεκάς), meaning "a group of ten."
Duration in Other Units
1 decade equals:
- 10 years (exactly)
- 120 months (10 × 12 months)
- ~520 weeks (10 × 52.18 weeks)
- 3,652 days (common years) or 3,653 days (including leap years)
- Average: 3,652.5 days (accounting for leap year cycle)
- 87,660 hours (3,652.5 × 24)
- 5,259,600 minutes (87,660 × 60)
- 315,576,000 seconds (5,259,600 × 60)
Decade Boundaries: The 0 vs. 1 Debate
Popular usage (dominant):
- 1980s = 1980, 1981, 1982, 1983, 1984, 1985, 1986, 1987, 1988, 1989 (years ending 0-9)
- 1990s = 1990-1999
- 2000s = 2000-2009
- 2010s = 2010-2019
- 2020s = 2020-2029
Formal reckoning (pedantic, rarely used):
- Because there was no year 0 in the Gregorian calendar (1 BCE → 1 CE directly), decades "should" span 1-10:
- 1st decade = 1-10 CE
- 199th decade = 1981-1990
- 200th decade = 1991-2000
- 201st decade = 2001-2010
Reality: Popular usage (0-9) dominates overwhelmingly. When people say "the 1980s," they mean 1980-1989, not 1981-1990. Cultural identity, nostalgia, and historical analysis all use the 0-9 convention.
Note: The Week is part of the imperial/US customary system, primarily used in the US, UK, and Canada for everyday measurements. The Decade belongs to the imperial/US customary system.
History of the Week and Decade
of the Week
Ancient Babylonian Origins (c. 2000-1000 BCE)
The 7-day week's roots lie in ancient Mesopotamian astronomy and astrology:
Babylonian astronomy:
-
Observed seven "wandering stars" (planets) visible to naked eye:
- Sun (Shamash) - brightest object
- Moon (Sin) - most obviously changing
- Mercury (Nabu) - messenger god
- Venus (Ishtar) - morning/evening star
- Mars (Nergal) - red planet, war god
- Jupiter (Marduk) - king of gods
- Saturn (Ninurta) - slow-moving
-
Each celestial body "ruled" one day
-
Seven was considered mystical/sacred number
-
Used in astrological predictions and religious rituals
Why 7 was special:
- Seven visible "planets" (including Sun and Moon)
- Seven days between moon phases (~7.4 days per quarter)
- Mathematical: 7 is prime, making it special
- Religious significance in Near Eastern cultures
Note: The moon's phases (29.5 days ÷ 4 ≈ 7.4 days) may have influenced the 7-day cycle, though it doesn't align perfectly.
Jewish Religious Codification (c. 1500-500 BCE)
The Hebrew Bible (Torah) embedded the 7-day week in religious law:
Genesis creation narrative (Genesis 1:1-2:3):
- Day 1: Light and darkness
- Day 2: Sky and waters
- Day 3: Land, seas, plants
- Day 4: Sun, moon, stars
- Day 5: Fish and birds
- Day 6: Land animals and humans
- Day 7: God rested → Sabbath (Shabbat)
Fourth Commandment (Exodus 20:8-11):
"Remember the Sabbath day, to keep it holy. Six days you shall labor and do all your work, but the seventh day is a Sabbath to the Lord your God."
Sabbath observance:
- Saturday (7th day) as mandatory day of rest
- No work permitted (cooking, travel, commerce)
- Synagogue worship and family meals
- Violations carried severe penalties (death in ancient times)
- Core to Jewish identity for 3,000+ years
Jewish week structure:
- Days numbered: Yom Rishon (Day 1) through Yom Shishi (Day 6)
- Only Shabbat (Sabbath, Day 7) has a name
- Week begins Saturday evening (sunset) and ends following Saturday sunset
Greek and Roman Adoption (300 BCE - 400 CE)
Greek influence:
- Hellenistic astronomers (post-Alexander) adopted Babylonian astrology
- Each day associated with a planet/deity
- Week spread through Greek-speaking world
- Ptolemy's astrology (2nd century CE) codified planetary hours and days
Roman nundinal cycle (753 BCE - 321 CE):
- Romans initially used 8-day market week (nundinae)
- Days labeled A through H
- Markets held every 8th day
- Used for agricultural and commercial scheduling
Planetary week adoption (1st-3rd century CE):
- 7-day planetary week entered Rome from Near East
- Coexisted with 8-day nundinal cycle
- Gradually replaced nundinal week for religious/astrological reasons
- Days named after planets/gods:
- Dies Solis (Sun) → Sunday
- Dies Lunae (Moon) → Monday
- Dies Martis (Mars) → Tuesday (Tiw = Germanic Mars)
- Dies Mercurii (Mercury) → Wednesday (Woden = Germanic Mercury)
- Dies Jovis (Jupiter) → Thursday (Thor = Germanic Jupiter)
- Dies Veneris (Venus) → Friday (Frigg = Germanic Venus)
- Dies Saturni (Saturn) → Saturday
Constantine's decree (321 CE):
- Emperor Constantine I officially recognized the 7-day week
- Declared Sunday (Dies Solis) a day of rest
- Aligned with Christian practice (resurrection day)
- Marked official end of nundinal cycle
- Made 7-day week legal standard across Roman Empire
Christian Transformation (1st-5th century CE)
Early Christian practice:
- Jewish Christians initially observed Saturday Sabbath
- Gradually shifted to Sunday (Dies Dominica, "Lord's Day")
- Commemorated Jesus's resurrection (Sunday morning)
- Sunday worship established by 100 CE
Christian week structure:
- Sunday: Lord's Day, primary worship
- Monday-Saturday: Workdays
- No Sabbath work prohibition (unlike Judaism)
- Sunday rest became custom, not religious law initially
Church influence:
- Constantine's decree (321 CE) made Sunday official rest day
- Christian terminology replaced pagan planet names in some languages:
- Portuguese: Domingo (Sunday = Lord's Day), Segunda-feira (Monday = Second day)
- Some Slavic languages: similar pattern
- Christian calendar organized around Sunday as "first day of week" (Western tradition)
Medieval Christian week:
- Elaborate liturgical calendar
- Different saints' days on specific weekdays
- Friday fasting (commemorating crucifixion)
- Sunday mandatory Mass attendance
- Week structured around religious observances
Islamic Adoption (7th century CE)
Islamic week (al-usbūʿ):
- Adopted existing 7-day week structure
- Friday (Jumu'ah) designated as day of congregational prayer
- Not a "day of rest" like Sabbath/Sunday—work permitted
- Friday midday prayer (Jumu'ah prayer) mandatory for men
Islamic day names:
- Days numbered similar to Hebrew tradition
- Saturday: Yawm as-Sabt (Day of the Sabbath—Hebrew influence)
- Sunday: Yawm al-Ahad (First day)
- Monday: Yawm al-Ithnayn (Second day)
- ...
- Friday: Yawm al-Jumu'ah (Day of Congregation)
Spread of Islamic week:
- Islamic expansion (7th-15th centuries) spread 7-day week to:
- North Africa
- Middle East
- Central Asia
- Parts of Southeast Asia
- Reinforced 7-day week as global standard
Global Standardization (1500-1900)
European colonialism:
- Spanish, Portuguese, French, British empires spread 7-day week
- Christian Sunday observance imposed in colonies
- Replaced indigenous time-keeping systems:
- Aztec 13-day and 20-day cycles
- Mayan complex calendar system
- Various Asian lunar-based systems
East Asia adoption:
- China: Adopted 7-day week in early 20th century (previously used 10-day xún divisions)
- Japan: Officially adopted 7-day week in 1873 during Meiji Restoration
- Korea: Adopted with modernization in late 19th/early 20th century
International commerce:
- Global trade required synchronized schedules
- Shipping and maritime schedules used 7-day week
- Telegraph and later telecommunications standardized weekly communications
Failed Reform Attempts
Despite universal adoption, several attempts to "improve" the week failed:
1. French Revolutionary Calendar (1793-1805):
- Replaced 7-day week with 10-day décade
- Aligned with metric system (10 days per week, 3 weeks per month)
- Days numbered Primidi through Décadi
- Only Décadi was rest day (1 in 10 vs. 1 in 7)
- Failed because:
- Less frequent rest days unpopular with workers
- Conflicted with Christian Sunday observance
- Disrupted social and family patterns
- Napoleon abolished it in 1805
2. Soviet 5-day and 6-day weeks (1929-1940):
-
1929-1931: 5-day "continuous week"
- Days numbered 1-5
- Each worker got one of five days off (rotating)
- Goal: Continuous factory production
- Problem: Families/friends couldn't synchronize time off
-
1931-1940: 6-day week
- Days numbered 1-6
- Day 6 was universal rest day
- Goal: Improve on 5-day system
- Problem: Still disrupted religious observance, traditional patterns
-
1940: Return to 7-day week
- Abandoned experiments
- Restored traditional Sunday rest
- 7-day week too culturally embedded to change
3. International Fixed Calendar (1923-present, never adopted):
- Proposed by Moses B. Cotsworth
- 13 months of 28 days each (4 perfect weeks per month)
- Extra month called "Sol" between June and July
- One "Year Day" outside the weekly cycle
- Never adopted because:
- Would disrupt all existing calendars
- Breaking the continuous 7-day cycle unacceptable religiously
- Massive economic costs
- Resistance from established institutions
4. Other proposals:
- Decimal weeks (10 days)
- 5-day weeks (aligned with work week)
- 8-day weeks (better divides into month)
- All failed: Cultural inertia too strong
Modern Universal Adoption
Current status:
- All 195+ countries use the 7-day week
- Synchronized globally despite cultural differences
- ISO 8601 standard (Monday = day 1, week 1 contains first Thursday)
- Different weekend patterns:
- Saturday-Sunday: Most of world (Christian tradition)
- Friday-Saturday: Many Muslim countries (Saudi Arabia, UAE until 2022)
- Friday only: Iran
- Sunday only: Historical in some countries
Why 7-day week succeeded:
- Religious universality: Judaism, Christianity, Islam all use 7-day week
- Ancient origins: 3,000+ years of continuity
- Global colonization: European powers spread it worldwide
- Economic integration: International commerce requires synchronization
- Cultural entrenchment: Too deeply embedded to change
- Mathematical convenience: Fits reasonably with months (4-5 weeks)
- Work-rest balance: 5-2 or 6-1 work-rest ratio culturally accepted
Modern cultural significance:
- Phrase "work week" universal
- "Weekend" concept global (even if different days)
- Weekly planning horizon standard
- Pay periods often weekly or bi-weekly
- Television programming on weekly schedules
- Religious observances every 7 days
- Social rhythms organized weekly
of the Decade Concept
1. Ancient Origins: Base-10 Counting (Prehistoric)
The human preference for base-10 (decimal) counting stems from having 10 fingers, making groups of 10 natural for organization.
Early base-10 applications:
- Ancient Egypt (~3000 BCE): Hieroglyphic numerals based on powers of 10
- Ancient China (~1500 BCE): Decimal system in oracle bone inscriptions
- Ancient Greece (~500 BCE): Decimal counting, though 12 and 60 also important
- Ancient Rome: Latin "decem" (ten) gave root to "decade"
Why 10-year groups? Humans naturally organize time into manageable chunks. A year is too short for long-term trends, a century too long for human memory—a decade provides a Goldilocks timescale for pattern recognition.
2. Medieval and Renaissance Period (500-1600 CE)
"Decade" as general term:
- Originally meant any group of 10 (10 books, 10 prayers, 10 beads)
- Rosary decades: Catholic rosary divided into 5 decades (groups of 10 Hail Marys)
- Literary decades: Collections of 10 stories or books (e.g., Boccaccio's "Decameron" = 10 days of stories)
Not yet specifically time-related: Medieval and Renaissance writers used "decade" for groupings, but not systematically for 10-year periods in historical analysis.
3. Enlightenment and Modern Historical Analysis (1700s-1800s)
Systematic historical periodization emerged:
- 18th-century historians began organizing events by 10-year periods for analysis
- Statistical thinking (late 1700s-1800s): Governments collected data in 10-year intervals
- US Census (1790-present): Conducted every 10 years, reinforcing decade thinking
- Economic cycles: Analysts noticed decade-scale patterns in markets, trade
Why decades gained prominence:
- Human lifespan scale: 10 years = noticeable change but within living memory
- Generational overlap: Enough time for trends to develop but not so long that witnesses die
- Data collection: Census and economic data naturally aligned with 10-year cycles
- Psychological salience: Decade birthdays (30, 40, 50, 60) mark life transitions
4. 20th Century: Decades as Cultural Identifiers (1900s-2000s)
The 20th century saw decades become powerful cultural and historical labels:
Early examples:
- "The Gay Nineties" (1890s): Retrospective label for late Victorian optimism
- "The Roaring Twenties" (1920s): Jazz Age, prohibition, economic boom, flapper culture
- "The Thirties" (1930s): Great Depression, Dust Bowl, rise of fascism
Post-WWII decade labels (most influential):
- "The Fifties" (1950s): Post-war prosperity, suburbs, rock and roll, Cold War begins
- "The Sixties" (1960s): Civil rights, Vietnam War, counterculture, sexual revolution, moon landing
- "The Seventies" (1970s): Disco, oil crisis, stagflation, Watergate, punk rock
- "The Eighties" (1980s): Reagan/Thatcher, Cold War end, MTV, personal computers, Wall Street boom
- "The Nineties" (1990s): Grunge, dot-com boom, end of Cold War, globalization, early internet
Why 20th-century decades are so culturally distinct:
- Rapid change: Technology, politics, culture shifted dramatically every 10 years
- Mass media: Radio (1920s-50s), TV (1950s-2000s), MTV (1980s-90s) amplified decade identity
- Music genres: Each decade had distinctive music (jazz/20s, rock/50s, disco/70s, grunge/90s)
- Fashion cycles: 10-year fashion trends reinforced decade boundaries
- Political eras: Often aligned with decade boundaries (Kennedy/60s, Reagan/80s)
5. 21st Century: Digital Age Decades (2000s-Present)
New challenges to decade identity:
- "The 2000s" = linguistic problem (no catchy name: noughties? aughts? two-thousands?)
- Faster change: Internet, smartphones, social media accelerate cultural shifts
- Decade labels less distinct: 2000s and 2010s harder to characterize uniquely
- Nostalgia cycles: 1980s and 1990s nostalgia dominated 2010s-2020s
2000s decade naming attempts:
- "Noughties" (British English): From "nought" (zero)
- "Aughts" (American English): From "aught" (zero, archaic)
- "Two-thousands": Clunky but functional
- "The zeros": Rarely used
2010s:
- "The twenty-tens" or "the tens": More natural linguistically
- Cultural markers: Smartphones ubiquitous, social media dominance, streaming services
2020s (current decade):
- "The twenties": Natural label, but overlaps with "Roaring Twenties" (1920s)
- COVID-19 pandemic (2020-2023) defined early decade
- Climate change, AI revolution, geopolitical shifts
Common Uses and Applications: weeks vs decades
Explore the typical applications for both Week (imperial/US) and Decade (imperial/US) to understand their common contexts.
Common Uses for weeks
When to Use decades
and Applications
1. Age and Life Stage Communication
"In my [decade]" describes life stage:
- "In my twenties": Young adulthood, career building, dating/marriage
- "In my thirties": Career advancement, family raising, homeownership
- "In my forties": Peak earning years, midlife transitions
- "In my fifties": Late career, empty nest, retirement planning
- "In my sixties": Retirement, grandparenting, senior status
More specific than single age: "I'm in my early thirties" conveys life stage better than "I'm 32."
2. Historical Analysis and Research
Decade-by-decade comparison standard:
- "Income in 1970 vs. 2020": 5-decade comparison
- "Homicide rates declined every decade since 1990s": Decade-scale trend
- "Technology adoption: 2000s smartphones, 2010s tablets, 2020s AI"
Academic papers often structured by decade:
- "This study examines voting patterns across three decades (1980s-2000s)"
3. Goal Setting and Life Planning
"Where do you see yourself in 10 years?" = classic interview/life question
10-year planning horizons:
- Personal goals: "Get promoted within a decade," "Be debt-free in 10 years"
- Savings goals: "Save $100K over next decade"
- Health goals: "Run marathon before I turn 40" (decade milestone)
Vision boards and bucket lists: Often include decade milestones (30th birthday trip, 40th marathon).
4. Demographic and Market Segmentation
Age groups by decade:
- 18-29: Young adults (target for entry-level products, dating apps)
- 30-39: Prime family/career demographic (target for houses, minivans, life insurance)
- 40-49: Peak earning (target for luxury goods, college savings plans)
- 50-59: Pre-retirement (target for wealth management, travel)
- 60+: Seniors (target for retirement services, healthcare)
Market research: "Millennials in their thirties prefer [X], while Gen X in their fifties prefer [Y]."
5. Forecasting and Trend Prediction
"Next decade" predictions common:
- Technology: "AI will transform work in the next decade"
- Climate: "2020s critical decade for climate action"
- Economics: "Inflation forecasts for the decade ahead"
Industry roadmaps: Auto industry "2030 targets" = decade-scale planning (all-electric by 2030).
6. Reunion and Anniversary Events
Class reunions every decade:
- 10-year reunion: Compare life trajectories, still young
- 20-year reunion: Mid-life, established careers/families
- 30-year reunion: Late career, nostalgia peaks
- 50-year reunion: Senior years, mortality awareness
Anniversary milestones: Companies, organizations celebrate 10th, 25th, 50th, 100th anniversaries.
7. Sports Records and Comparisons
"Athlete of the Decade" awards:
- AP Athlete of the Decade: Michael Jordan (1990s), Tiger Woods (2000s), Lionel Messi (2010s)
- Team dominance: "Yankees dominated baseball in 1990s," "Patriots dynasty in 2010s"
Decade statistics: "Home runs per decade in MLB" = long-term trend analysis.
Additional Unit Information
About Week (wk)
How many days are in a week?
Exactly 7 days in every week, universally across all cultures and countries worldwide.
This has been standard for over 2,000 years, originating from:
- Ancient Babylonian astronomy (7 visible celestial bodies)
- Jewish religious tradition (Genesis 7-day creation + Sabbath)
- Roman adoption and global spread
The 7-day week has no astronomical basis (unlike day or year) but achieved universal cultural adoption.
How many hours are in a week?
Exactly 168 hours in one week.
Calculation: 7 days × 24 hours/day = 168 hours
Context:
- Work week: 40 hours (standard full-time) out of 168 total
- Sleep: 56 hours per week (8 hours/night × 7 nights)
- Leisure: 168 - 40 (work) - 56 (sleep) = 72 hours
- Work-life balance: Only ~24% of week spent working (40/168)
Why does a week have 7 days?
The 7-day week has cultural and religious origins, not astronomical:
Three main reasons:
-
Babylonian astronomy (c. 2000 BCE):
- Seven visible "planets": Sun, Moon, Mercury, Venus, Mars, Jupiter, Saturn
- Each day dedicated to one celestial body
- Seven considered sacred number
-
Jewish religious tradition (c. 1500 BCE):
- Genesis: God created world in 6 days, rested on 7th (Sabbath)
- Fourth Commandment: "Remember the Sabbath day"
- Embedded in religious law for 3,000+ years
-
Global adoption:
- Christianity spread Sunday worship (resurrection day)
- Islam adopted 7-day week with Friday prayers
- Roman Empire standardized it (321 CE Constantine decree)
- Colonial expansion made it universal
Why not 5, 8, or 10 days? All attempts to change it failed (French 10-day, Soviet 5/6-day weeks) due to deep cultural and religious entrenchment.
How many weeks are in a year?
52.14 weeks in a standard 365-day year.
Calculation: 365 days ÷ 7 days/week = 52.14 weeks (52 weeks + 1 day)
More precisely:
- Common year (365 days): 52 weeks + 1 day
- Leap year (366 days): 52 weeks + 2 days
Practical implications:
- 52 "full weeks" per year
- Extra 1-2 days cause annual calendar drift
- Same date falls on different day of week each year
ISO week-numbering:
- Most years: Weeks 1-52
- Some years: Weeks 1-53 (when year has 53 Thursdays)
What is a work week?
A work week is the 5-day period from Monday-Friday when most businesses operate, totaling 40 hours (8 hours/day × 5 days) in the US standard.
Work week structure:
- Weekdays: Monday-Friday (5 days) - work/school days
- Weekend: Saturday-Sunday (2 days) - rest days
- 5-2 split: 5 days work, 2 days rest
Hours:
- US full-time: 40 hours per week standard
- France: 35 hours per week legal standard
- Part-time: 20-30 hours per week
- Overwork: 50-60+ hours per week
Variations:
- 4-day work week: Emerging trend (32-40 hours over 4 days)
- 6-day work week: Historical standard, still common in some countries
- Muslim countries: Friday-Saturday weekend (work Sunday-Thursday)
Origins:
- Industrial Revolution: Standardized factory schedules
- Labor movements: Won 5-day, 40-hour week (1926-1940 in US)
- Henry Ford: Pioneered 5-day, 40-hour week (1926)
- Fair Labor Standards Act (1938): Codified 40-hour week in US
What is the weekend?
The weekend is the 2-day period of rest at the end of the work week, typically Saturday and Sunday in Western countries.
Weekend structure:
- Saturday: First day off
- Sunday: Second day off, traditional Christian day of worship
- Purpose: Rest, recreation, family time, errands
Global variations:
- Western countries: Saturday-Sunday (majority of world)
- Muslim countries: Friday-Saturday or Friday-Sunday (historically)
- Saudi Arabia, UAE: Switched to Saturday-Sunday in 2022
- Iran: Friday only
- Israel: Friday-Saturday (aligns with Jewish Sabbath)
- Brunei, Bangladesh: Friday-Saturday
Origins:
- Jewish Sabbath: Saturday rest day (biblical commandment)
- Christian Sunday: Lord's Day (resurrection observance)
- Industrial era: Originally only Sunday off
- 1920s-1940s: Saturday added, creating "weekend"
- Labor advocacy: "Saturday half-day" became full day off
Cultural significance:
- "Thank God It's Friday" (TGIF)
- "Weekend warrior" (active on weekends)
- "Monday blues" (dreading return to work)
- Weekend social events, sports, entertainment
How many weeks are in a month?
Approximately 4.35 weeks in an average month.
Calculation:
- Average month = 30.44 days (365 ÷ 12)
- 30.44 days ÷ 7 days/week = 4.35 weeks
Actual variation:
- February: 4.0 weeks (28 days), 4.14 weeks (29 days, leap year)
- 30-day months: 4.29 weeks (April, June, September, November)
- 31-day months: 4.43 weeks (January, March, May, July, August, October, December)
Why not exactly 4 weeks?
- 4 weeks = 28 days
- Most months = 30-31 days
- 2-3 days "extra" per month
Implications:
- "Monthly" ≠ "every 4 weeks"
- Monthly salary ≠ 4 weekly salaries
- Rent is monthly (12 times/year), not 4-weekly (13 times/year)
What is a fortnight?
A fortnight is a period of 14 days or 2 weeks.
Origin:
- Old English: fēowertīene niht = "fourteen nights"
- Common in British English
- Less common in American English
Usage:
- UK: "I'll see you in a fortnight" (2 weeks from now)
- Australia/New Zealand: Common term
- Pay periods: "Fortnightly pay" = paid every 2 weeks
- Planning: "Fortnight holiday" = 2-week vacation
Related terms:
- Bi-weekly: Every 2 weeks (26 times per year)
- Semi-monthly: Twice per month (24 times per year)
- Fortnight = bi-weekly interval, not semi-monthly
Why do weekends exist?
Weekends exist due to religious tradition and labor reform:
Religious origins:
- Jewish Sabbath: Saturday rest day (biblical commandment, ~3,000 years old)
- Christian Sunday: Lord's Day, resurrection observance (2,000 years old)
- Both religions mandate one day of rest per week
Industrial era (1800s-1900s):
- Initially: 6-day work week, only Sunday off (Christian influence)
- Workers labored Monday-Saturday, 10-16 hours per day
- Exhausting, no family time
Labor reform (1900s):
- 1908: First 5-day work week proposed
- 1926: Henry Ford adopted 5-day, 40-hour week (factory efficiency + consumer spending)
- 1929: Great Depression led to work-sharing (reduce hours to employ more)
- 1938: Fair Labor Standards Act (US) established 40-hour week with overtime
- 1940: 5-day work week became US standard
Why 2-day weekend prevailed:
- Productivity: Workers more productive with adequate rest
- Consumer economy: Workers with free time spend money
- Family time: Social benefits
- Religious observance: Accommodates both Saturday (Jewish) and Sunday (Christian)
- Union advocacy: Labor movements fought for it
Modern trends:
- 4-day work week experiments (same hours, compressed)
- Flexible schedules: "Weekend" varies by individual
- Remote work blurs work-weekend boundaries
Can weeks start on different days?
Yes, weeks can start on either Sunday or Monday depending on cultural convention, though the 7-day cycle remains constant.
Two main systems:
1. Sunday-first (traditional Christian):
- Used in: United States, Canada, parts of Latin America
- Rationale: Sunday is the Lord's Day, "first day of week" in Christian tradition
- Calendars: US calendars show Sunday as leftmost column
- Biblical: Genesis creation starts with Sunday
2. Monday-first (ISO standard):
- Used in: Europe, Asia, Africa, Australia (most of world)
- ISO 8601 standard: Monday = day 1, Sunday = day 7
- Rationale: Work week starts Monday, weekend (Saturday-Sunday) grouped together
- Calendars: International calendars show Monday as leftmost column
Which is "correct"?
- Both are valid cultural conventions
- ISO 8601 standardizes Monday-first for international business/computing
- Work week universally Monday-Friday regardless
Computing:
- Programming: ISO 8601 standard (Monday = 1)
- Excel/Google Sheets: Can be configured either way
- Date/time libraries: Often use ISO standard
Practical impact:
- Minimal—everyone uses same 7-day cycle
- Only affects calendar layout and "first day" reference
- "Weekend" always means Saturday-Sunday (or local equivalent)
About Decade (dec)
1. How many years are in one decade?
Exactly 10 years. The word "decade" comes from Greek "dekas" (δεκάς), meaning "group of ten."
Other units:
- 1 decade = 10 years = 120 months = ~3,652.5 days = 87,660 hours
2. How are decades typically named or referred to?
By tens digit: "The 1980s" (1980-1989), "the 2020s" (2020-2029).
Nicknames for famous decades:
- 1920s: "The Roaring Twenties," "The Jazz Age"
- 1950s: "The Fifties"
- 1960s: "The Sixties," "The Swinging Sixties"
- 2000s: "The Noughties" (UK), "The Aughts" (US), "The Two-Thousands"
3. Does a decade start with a year ending in 0 or 1?
Popular usage (dominant): Decades start with years ending in 0.
- The 1980s = 1980-1989
- The 2020s = 2020-2029
Formal reckoning (rarely used): Because there was no year 0, decades technically span 1-10.
- The 199th decade = 1981-1990
Conclusion: Popular usage (0-9) dominates in all practical contexts.
4. What decade am I in if I'm 35 years old?
You're in your fourth decade of life.
Breakdown:
- First decade: Birth (0) to 10th birthday (10) = ages 0-9
- Second decade: Ages 10-19
- Third decade: Ages 20-29
- Fourth decade: Ages 30-39 ← You are here at age 35
- Fifth decade: Ages 40-49
Mnemonic: Count the completed decades + 1. At age 35, you've completed 3 decades (0-10, 10-20, 20-30) and are in your 4th.
5. Is the decade an SI unit?
No. The decade is not part of the International System of Units (SI). The SI base unit for time is the second.
Non-SI time units commonly used:
- Minute (60 seconds)
- Hour (3,600 seconds)
- Day (~86,400 seconds)
- Year (~31.5 million seconds)
- Decade (~315 million seconds)
Scientific contexts: Research often uses SI units like kiloyears (kyr = 1,000 years) or megayears (Myr = 1 million years) rather than decades.
6. How many days are in a decade?
Approximately 3,652.5 days (accounting for leap years).
Calculation:
- 10 years × 365 days = 3,650 days
- Plus ~2.5 leap days per decade = 3,652.5 days
Exact number varies: Depends on leap year distribution in the specific decade.
- Decade with 2 leap years: 3,652 days
- Decade with 3 leap years: 3,653 days
7. What's the difference between a decade and a generation?
Decade: Exactly 10 years, used for historical/cultural periodization.
Generation: Approximately 20-30 years, the average time between birth of parents and birth of their children.
Generations span multiple decades:
- Baby Boomers (1946-1964): ~2 decades
- Generation X (1965-1980): ~1.5 decades
- Millennials (1981-1996): ~1.5 decades
- Generation Z (1997-2012): ~1.5 decades
Key difference: Decade = fixed 10 years; generation = variable ~20-30 years based on demographic/cultural cohorts.
8. Why are decades important in history and culture?
Human-scale timescale: 10 years is long enough for significant change but short enough to remember/experience.
Pattern recognition: Decade groupings reveal trends invisible in year-by-year analysis.
Cultural identity: Decades serve as convenient labels for distinct eras ("the Sixties," "the Eighties").
Psychological salience: Decade milestones (10, 20, 30, 40) feel more significant than other ages.
Media influence: 20th-century mass media amplified decade identity through music, fashion, political eras.
9. What is a "lost decade"?
Economic term: A decade of economic stagnation or decline, minimal growth.
Famous examples:
- Japan's Lost Decade (1990s): Asset bubble burst → prolonged recession
- Actually extended into "Lost Two Decades" or "Lost Three Decades" (1990s-2010s)
- Latin America's Lost Decade (1980s): Debt crisis → stagnation
- US "Lost Decade" (2000s): Dot-com crash (2000) + Financial crisis (2008) = weak growth
Personal context: "Lost decade" can mean any 10-year period of personal stagnation or hardship.
10. How do I calculate how many decades between two years?
Formula: decades = (ending year - starting year) ÷ 10
Examples:
- 1980 to 2020: (2020 - 1980) ÷ 10 = 4 decades (40 years)
- 1995 to 2025: (2025 - 1995) ÷ 10 = 3 decades (30 years)
- 2000 to 2018: (2018 - 2000) ÷ 10 = 1.8 decades (18 years)
11. What are decennial events?
Decennial = occurring every 10 years (once per decade).
Examples:
- US Census: Conducted every 10 years (1790, 1800, ... 2020, 2030)
- 10th anniversaries: Wedding, company founding, event commemoration
- High school reunions: Often every 10 years (10th, 20th, 30th)
Etymology: From Latin "decennium" (decem = ten, annus = year).
12. How many decades in a century? In a millennium?
Century:
- 1 century = 100 years = 10 decades
Millennium:
- 1 millennium = 1,000 years = 100 decades
Conversions:
- 5 decades = 50 years = 0.5 centuries
- 20 decades = 200 years = 2 centuries = 0.2 millennia
Conversion Table: Week to Decade
| Week (wk) | Decade (dec) |
|---|---|
| 0.5 | 0.001 |
| 1 | 0.002 |
| 1.5 | 0.003 |
| 2 | 0.004 |
| 5 | 0.01 |
| 10 | 0.019 |
| 25 | 0.048 |
| 50 | 0.096 |
| 100 | 0.192 |
| 250 | 0.479 |
| 500 | 0.958 |
| 1,000 | 1.917 |
People Also Ask
How do I convert Week to Decade?
To convert Week to Decade, enter the value in Week in the calculator above. The conversion will happen automatically. Use our free online converter for instant and accurate results. You can also visit our time converter page to convert between other units in this category.
Learn more →What is the conversion factor from Week to Decade?
The conversion factor depends on the specific relationship between Week and Decade. You can find the exact conversion formula and factor on this page. Our calculator handles all calculations automatically. See the conversion table above for common values.
Can I convert Decade back to Week?
Yes! You can easily convert Decade back to Week by using the swap button (⇌) in the calculator above, or by visiting our Decade to Week converter page. You can also explore other time conversions on our category page.
Learn more →What are common uses for Week and Decade?
Week and Decade are both standard units used in time measurements. They are commonly used in various applications including engineering, construction, cooking, and scientific research. Browse our time converter for more conversion options.
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Verified Against Authority Standards
All conversion formulas have been verified against international standards and authoritative sources to ensure maximum accuracy and reliability.
National Institute of Standards and Technology — Official time standards and definitions
Bureau International des Poids et Mesures — Definition of the SI base unit for time
Last verified: December 3, 2025