Celsius (°C) - Unit Information & Conversion
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What is a Celsius?
Celsius (°C) is the most widely used temperature scale worldwide, defining 0°C as the freezing point of water and 100°C as its boiling point at standard atmospheric pressure. Used in weather forecasts, scientific research, medicine, cooking, and everyday temperature measurements in virtually every country except the United States. The Celsius scale provides intuitive reference points based on water phase transitions, making it the global standard for temperature measurement.
History of the Celsius
Developed by Swedish astronomer Anders Celsius in 1742, who originally proposed an inverted scale (0° for boiling, 100° for freezing). The scale was reversed posthumously by Carl Linnaeus or possibly Jean-Pierre Christin to the modern form (0° freezing, 100° boiling). The name "Centigrade" (meaning "hundred steps") was used until 1948, when the 9th General Conference on Weights and Measures officially renamed it "Celsius" to honor its inventor and avoid confusion with the angular measurement centigrade. Celsius was formally adopted into the International System of Units (SI) in 1948, defined relative to the Kelvin scale with 0°C = 273.15 K. The scale gained universal adoption throughout the 20th century as countries worldwide adopted the metric system, with the United States remaining the primary exception. Today, Celsius is the de facto standard for weather reporting, medical thermometry, scientific research, and everyday temperature measurement in over 190 countries.
Quick Answer: What is Celsius?
Celsius (°C) is a temperature scale where 0°C is the freezing point of water and 100°C is the boiling point at standard atmospheric pressure. It's the global standard temperature scale used in virtually every country except the United States.
Key conversions:
- 0°C = 32°F = 273.15 K (Water freezes)
- 20°C = 68°F = 293.15 K (Room temperature)
- 37°C = 98.6°F = 310.15 K (Body temperature)
- 100°C = 212°F = 373.15 K (Water boils)
Common uses: Weather forecasts, cooking temperatures, medical thermometry, scientific research, HVAC systems, and everyday temperature measurements worldwide.
Important note: The US uses Fahrenheit instead of Celsius, requiring conversion for international communication. Use our temperature converter for instant conversions.
Quick Comparison Table
| Celsius | Fahrenheit | Kelvin | Context | Convert Now |
|---|---|---|---|---|
| -273.15°C | -459.67°F | 0 K | Absolute zero (coldest possible) | Convert → |
| -40°C | -40°F | 233.15 K | Extreme cold (scales coincide) | Convert → |
| -18°C | 0°F | 255.15 K | Typical freezer temperature | Convert → |
| 0°C | 32°F | 273.15 K | Water freezes | Convert → |
| 10°C | 50°F | 283.15 K | Cool autumn day | Convert → |
| 20°C | 68°F | 293.15 K | Comfortable room temperature | Convert → |
| 37°C | 98.6°F | 310.15 K | Normal body temperature | Convert → |
| 100°C | 212°F | 373.15 K | Water boils | Convert → |
| 180°C | 356°F | 453.15 K | Standard baking temperature | Convert → |
Need a different conversion? Try our temperature converter for all temperature units.
Definition
What Is Celsius?
Degree Celsius (°C) is a unit of temperature on the Celsius scale, a temperature scale originally named "Centigrade" and renamed to honor Swedish astronomer Anders Celsius. It is the most common temperature scale used worldwide, adopted by virtually every country for everyday measurements and scientific work.
The Celsius scale is defined by two fixed points:
- 0°C: The freezing point of water at standard atmospheric pressure (1 atmosphere)
- 100°C: The boiling point of water at standard atmospheric pressure
The scale is divided into 100 equal intervals between these two points, making it a decimal-based (base-10) system that aligns perfectly with the metric system.
Modern scientific definition: Since 1954, Celsius has been defined relative to the Kelvin scale (the SI base unit for temperature):
- °C = K − 273.15
- K = °C + 273.15
This means a change of 1°C equals exactly a change of 1 K, but the zero points differ by 273.15 degrees.
Celsius vs. Other Temperature Scales
Celsius vs. Fahrenheit:
- Celsius: 0°C freezing, 100°C boiling (100-degree range)
- Fahrenheit: 32°F freezing, 212°F boiling (180-degree range)
- Conversion: °F = (°C × 9/5) + 32
- Use: Celsius used globally except US; Fahrenheit used primarily in US
Celsius vs. Kelvin:
- Celsius: Relative scale, can be negative, 0°C = freezing
- Kelvin: Absolute scale, no negative values, 0 K = absolute zero (-273.15°C)
- Conversion: K = °C + 273.15
- Use: Kelvin used in scientific contexts; Celsius for practical applications
Why Celsius is intuitive: The reference points (0°C and 100°C) are based on water phase transitions, which are fundamental to everyday life:
- Below 0°C: Water is solid (ice)
- 0°C to 100°C: Water is liquid
- Above 100°C: Water is gas (steam)
This makes Celsius immediately relatable—anyone who has seen ice melt or water boil understands these reference points.
History
Anders Celsius and the Original Scale (1742)
In 1742, Swedish astronomer Anders Celsius (1701–1744) proposed a temperature scale based on two fixed points related to water. However, his original scale was inverted from what we use today:
Celsius's original scale (1742):
- 0°: Boiling point of water
- 100°: Freezing point of water
This counterintuitive arrangement had water freezing at the higher number and boiling at the lower number. Celsius chose this orientation possibly because he was primarily interested in measuring cold temperatures in Sweden, making it convenient to have larger numbers for colder conditions.
Why inversion? Some historians believe Celsius wanted to avoid negative numbers when measuring cold Swedish winters. By setting freezing at 100°, he could measure winter temperatures as positive values above 100.
The Reversal: Modern Celsius Scale
Shortly after Celsius's death in 1744, the scale was reversed to its current form, where:
- 0°: Freezing point of water
- 100°: Boiling point of water
Who reversed it? Historical records are unclear, but credit is typically given to one or both:
- Carl Linnaeus (1707–1778): Swedish botanist who worked at Uppsala University with Celsius
- Jean-Pierre Christin (1683–1755): French physicist who independently proposed a similar reversed scale in 1743
The reversed scale proved more intuitive—negative numbers represent below-freezing temperatures, and positive numbers represent above-freezing, aligning with everyday experience.
From "Centigrade" to "Celsius" (1948)
For over 200 years, the scale was commonly known as "Centigrade," from the Latin words:
- "Centi": hundred
- "Grade": steps or degrees
The name described the scale's defining characteristic: 100 equal intervals between freezing and boiling.
The 1948 name change: In 1948, the 9th General Conference on Weights and Measures (CGPM) officially renamed the scale from "Centigrade" to "Celsius" for two important reasons:
- Honor Anders Celsius: Recognize the inventor's contribution to science
- Avoid confusion: The term "centigrade" was also used in French and Spanish to describe angular measurements (1/100th of a right angle), creating potential confusion in scientific contexts
The renaming standardized international terminology, making "Celsius" the official name in all languages and scientific literature.
Adoption into the Metric System (SI)
1954 - SI Integration: The 10th General Conference on Weights and Measures formally adopted Celsius into the International System of Units (SI) in 1954. Celsius was defined relative to the Kelvin scale:
- Kelvin: SI base unit for thermodynamic temperature
- Celsius: Derived unit, defined as K − 273.15
This integration meant Celsius became part of the coherent system of metric units used worldwide for science, engineering, and commerce.
1967-1968 - Definition refinement: The definition was refined to be based on the triple point of water (0.01°C, 273.16 K) rather than ice point and boiling point, providing a more precise scientific standard.
2019 - Modern definition: Following the 2019 redefinition of SI base units, the Kelvin (and thus Celsius) is now defined by fixing the Boltzmann constant, providing an even more fundamental and reproducible definition.
Global Adoption (20th Century)
Throughout the 20th century, Celsius adoption spread globally as countries adopted the metric system:
Early adopters (1790s-1800s):
- France and other European countries adopting metric system
- Gradual spread through scientific community
Mid-20th century (1960s-1980s):
- United Kingdom transitioned from Fahrenheit to Celsius (1960s-1970s)
- Canada adopted Celsius in 1975
- Australia, New Zealand adopted metric/Celsius (1960s-1970s)
- Most former British colonies transitioned to Celsius
Modern status:
- 190+ countries use Celsius as the official temperature scale
- 3 countries primarily use Fahrenheit: United States, Bahamas, Cayman Islands
- Universal in international aviation, shipping, science, and medicine
The US Exception
The United States remains the primary holdout, continuing to use Fahrenheit for:
- Weather forecasts
- Household thermostats
- Cooking temperatures (ovens, recipes)
- Public discourse
However, Celsius is used in US contexts:
- Scientific research (NASA, universities)
- Military
- Medical (increasingly, alongside Fahrenheit)
- International trade and diplomacy
Multiple attempts to convert the US to metric/Celsius (notably in the 1970s) have failed due to cultural resistance, conversion costs, and lack of political will.
Real-World Examples
1. Weather and Climate Temperatures
Extreme Cold:
- -89°C (-128°F): Coldest recorded temperature on Earth (Vostok Station, Antarctica, 1983)
- -50°C (-58°F): Extreme Arctic winter, exposed skin freezes in minutes
- -40°C (-40°F): Severe cold, point where Celsius and Fahrenheit scales coincide
- -30°C (-22°F): Extremely cold winter, dangerous without proper protection
- -20°C (-4°F): Very cold winter day in northern regions (Canada, Russia, Scandinavia)
- -10°C (14°F): Cold winter day, snow and ice common
Cold to Mild:
- 0°C (32°F): Freezing point, snow/ice forms, frost line
- 5°C (41°F): Cool spring/autumn day, light jacket weather
- 10°C (50°F): Cool but comfortable, sweater weather
- 15°C (59°F): Mild, pleasant day, perfect for outdoor activities
Comfortable Range:
- 20°C (68°F): Room temperature, very comfortable, typical thermostat setting
- 22°C (72°F): Warm and comfortable indoors
- 25°C (77°F): Warm summer day, T-shirt weather
- 28°C (82°F): Hot, air conditioning recommended
Hot to Extreme:
- 30°C (86°F): Hot summer day, stay hydrated
- 35°C (95°F): Very hot, heat exhaustion risk if prolonged
- 40°C (104°F): Extreme heat, dangerous without shade and water
- 45°C (113°F): Severe heat wave conditions, life-threatening
- 50°C (122°F): Record-breaking heat (Death Valley, Sahara Desert)
- 56.7°C (134°F): Hottest recorded temperature on Earth (Death Valley, 1913)
Use our temperature converter to compare Celsius and Fahrenheit values.
2. Cooking and Food Preparation
Refrigeration and Freezing:
- -18°C (0°F): Standard home freezer temperature for long-term food storage
- -12°C (10°F): Ice cream "soft serve" temperature
- 0°C (32°F): Freezing point, ice formation
- 4°C (39°F): Standard refrigerator temperature (safe food storage)
- 7-10°C (45-50°F): Wine storage temperature (varies by type)
Water Temperatures:
- 0°C (32°F): Ice water
- 20°C (68°F): Cool tap water
- 30-35°C (86-95°F): Lukewarm water, baby bath temperature
- 40-45°C (104-113°F): Hot tap water, comfortable for washing
- 50-60°C (122-140°F): Very hot tap water, hot water heater setting
- 100°C (212°F): Boiling water (sea level)
Meat Cooking Temperatures (internal):
- 55-60°C (131-140°F): Rare beef/lamb
- 60-65°C (140-149°F): Medium-rare beef/lamb
- 65-70°C (149-158°F): Medium beef/lamb
- 70-75°C (158-167°F): Medium-well beef/lamb
- 75°C (167°F): Well-done beef, safe minimum for poultry and pork
Oven Temperatures:
- 100-120°C (212-248°F): Dehydrating, meringue
- 140-160°C (284-320°F): Slow roasting, low-temperature cooking
- 160-180°C (320-356°F): Moderate baking (cakes, cookies, casseroles)
- 180-200°C (356-392°F): Standard baking temperature
- 200-220°C (392-428°F): Hot oven (roasting, bread)
- 220-250°C (428-482°F): Very hot oven (pizza, searing)
Convert cooking temperatures with our Celsius to Fahrenheit converter.
3. Medical and Body Temperatures
Body Temperature Range:
- 35°C (95°F): Hypothermia risk, medical attention needed
- 36°C (96.8°F): Mild hypothermia concern
- 36.5-37.5°C (97.7-99.5°F): Normal healthy body temperature range
- 37°C (98.6°F): Average normal body temperature
- 37.5-38°C (99.5-100.4°F): Slightly elevated, possible fever
- 38-39°C (100.4-102.2°F): Low-grade fever
- 39-40°C (102.2-104°F): Moderate fever, monitor closely
- 40-41°C (104-105.8°F): High fever, seek medical attention
- 41-42°C (105.8-107.6°F): Heat stroke risk, emergency
- Above 42°C (107.6°F): Critical hyperthermia, usually fatal
Medical Storage Temperatures:
- -196°C (-321°F): Liquid nitrogen storage (cryopreservation)
- -80°C (-112°F): Ultra-cold freezer (COVID-19 vaccines, research samples)
- -20°C (-4°F): Standard medical freezer (some vaccines, specimens)
- 2-8°C (36-46°F): Refrigerated vaccine storage (most vaccines)
- 20-25°C (68-77°F): Room temperature medication storage
4. Scientific and Laboratory Applications
Cryogenic Temperatures:
- -273.15°C (-459.67°F / 0 K): Absolute zero (theoretical coldest temperature)
- -269°C (-452°F): Liquid helium boiling point
- -196°C (-321°F): Liquid nitrogen boiling point (common cryogen)
- -183°C (-297°F): Liquid oxygen boiling point
- -78°C (-108°F): Dry ice (solid CO₂) sublimation point
Laboratory Standard Temperatures:
- 0°C (32°F): Ice point, calibration standard
- 20-25°C (68-77°F): Standard room temperature for experiments (often 20°C or 25°C specified)
- 37°C (98.6°F): Incubator temperature for cell culture (human body temperature)
- 56°C (133°F): Heat inactivation of complement proteins
- 95°C (203°F): DNA denaturation in PCR
- 100°C (212°F): Water boiling point, sterilization
Material Phase Transitions:
- 0°C (32°F): Water freezes/melts
- -38.8°C (-37.8°F): Mercury freezes
- 357°C (675°F): Mercury boils
- 1064°C (1947°F): Gold melts
- 1538°C (2800°F): Iron melts
- 3422°C (6192°F): Tungsten melts (highest melting point metal)
5. HVAC and Climate Control
Indoor Temperature Settings:
- 18-19°C (64-66°F): Cool bedroom temperature, good for sleeping
- 20-22°C (68-72°F): Standard comfortable room temperature, typical thermostat setting
- 22-24°C (72-75°F): Warm and comfortable
- 24-26°C (75-79°F): Air conditioning set point in summer
- Above 26°C (79°F): Uncomfortably warm indoors, productivity decreases
Water Heating:
- 50-60°C (122-140°F): Hot water heater setting (home use)
- 55°C (131°F): Recommended to prevent Legionella bacteria growth
- 60°C (140°F): Safe hot water temperature, kills most bacteria
Swimming Pools and Spas:
- 26-28°C (79-82°F): Competitive swimming pool temperature
- 28-30°C (82-86°F): Recreational pool temperature
- 32-34°C (90-93°F): Therapeutic pool temperature
- 37-40°C (99-104°F): Hot tub/spa temperature
6. Industrial and Manufacturing
Food Industry:
- -40°C (-40°F): Flash freezing for food preservation
- -18°C (0°F): Frozen food storage
- 5°C (41°F): Cold chain storage (perishables)
- 63°C (145°F): Hot holding temperature (food service)
- 72°C (162°F): Pasteurization temperature (flash method)
- 135°C (275°F): Ultra-high-temperature (UHT) sterilization
Plastic and Polymer Processing:
- 150-200°C (302-392°F): Injection molding for most plastics
- 180-230°C (356-446°F): Extrusion temperatures
- 250-300°C (482-572°F): High-temperature plastics (PEEK, PPS)
Metallurgy:
- 1000-1200°C (1832-2192°F): Steel forging temperature
- 1400-1600°C (2552-2912°F): Steel melting in blast furnaces
- 650-750°C (1202-1382°F): Aluminum casting temperature
7. Environmental and Climate Science
Climate Zones (Average Annual Temperature):
- Below -10°C (14°F): Polar/Arctic climate
- -10 to 10°C (14-50°F): Cold temperate climate (boreal/subarctic)
- 10-20°C (50-68°F): Temperate climate
- 20-25°C (68-77°F): Subtropical climate
- Above 25°C (77°F): Tropical climate
Global Climate Change Context:
- +1.1°C (1.9°F): Global average temperature increase since pre-industrial times (as of 2023)
- +1.5°C (2.7°F): Paris Agreement target limit for global warming
- +2°C (3.6°F): Dangerous climate change threshold
Common Uses
The Celsius scale is the standard temperature measurement in nearly all countries except the United States, and is used extensively across all fields:
1. Weather and Meteorology
The primary temperature scale for weather forecasts, climate data, and meteorological reports worldwide. All international weather organizations use Celsius as the standard.
Weather reporting:
- Daily forecasts (high/low temperatures)
- Heat warnings (above 30-35°C)
- Freeze warnings (below 0°C)
- Wind chill calculations
- Heat index calculations
Climate science:
- Historical temperature records
- Climate change monitoring
- Sea surface temperature measurements
- Atmospheric temperature profiles
- Glacial and polar ice monitoring
Common Conversions:
- Celsius to Fahrenheit (for US weather reports)
- Celsius to Kelvin (for scientific weather data)
2. Domestic and Everyday Use
Daily temperature measurements including thermostats, air conditioning units, water heaters, and personal thermometers in all metric countries.
Household applications:
- Home heating thermostat settings (18-22°C)
- Air conditioning settings (22-24°C)
- Water heater temperature (50-60°C)
- Refrigerator temperature (4°C)
- Freezer temperature (-18°C)
- Baby bath water (37°C)
- Laundry water temperatures (cold, 30°C, 40°C, 60°C, 90°C)
3. Science and Research
Universal standard in scientific research alongside Kelvin. Used in chemistry, biology, physics, earth sciences, and engineering for temperature measurements and calculations.
Why Scientists Use Celsius:
- Easy conversion to Kelvin (K = °C + 273.15)
- Intuitive water-based reference points
- Decimal-based like other SI units
- International standardization
- Direct relationship to Kelvin (1°C = 1 K difference)
Scientific applications:
- Chemical reactions and kinetics
- Material testing and properties
- Biological experiments and incubation
- Environmental monitoring
- Quality control testing
4. Medical and Healthcare
Standard for body temperature measurements, medical equipment calibration, pharmaceutical storage requirements, and clinical guidelines worldwide.
Medical Temperature Guidelines:
- Normal body temperature: 36.5-37.5°C
- Fever threshold: Above 38°C
- Hypothermia risk: Below 35°C
- Hyperthermia emergency: Above 40°C
- Vaccine storage: 2-8°C (refrigerated) or -20°C (frozen)
Medical equipment:
- Digital thermometers
- Incubators and warmers
- Sterilization equipment (autoclaves at 121°C or 134°C)
- Laboratory analyzers
- Blood storage (4°C for whole blood, -80°C for plasma)
Convert medical temperatures with our temperature converter.
5. Culinary and Food Safety
Used for cooking instructions, food storage, and safety guidelines in most countries. Recipe books, ovens, and cooking appliances display temperatures in Celsius.
Food Safety Temperatures:
- Danger zone: 5-60°C (41-140°F) - bacteria multiply rapidly
- Refrigeration: 0-4°C (32-39°F)
- Freezing: -18°C (0°F) or below
- Safe minimum cooking: 75°C (167°F) for most foods
- Poultry: 75°C (167°F) internal temperature
- Ground meat: 71°C (160°F) internal temperature
Common Oven Settings:
- Slow/Low: 120-150°C (248-302°F)
- Moderate: 160-180°C (320-356°F)
- Standard: 180-200°C (356-392°F)
- Hot: 200-230°C (392-446°F)
- Very Hot: 230-250°C (446-482°F)
Use our Celsius to Fahrenheit converter for recipe conversions.
6. HVAC and Climate Control
Standard unit for heating, ventilation, and air conditioning systems in commercial and residential buildings worldwide.
Climate control:
- Programmable thermostats
- Central heating systems
- Air conditioning units
- Heat pumps
- Industrial climate control
- Data center cooling
7. Education
Taught as the primary temperature scale in schools worldwide as part of the metric system curriculum.
Educational contexts:
- Elementary science (water freezing/boiling)
- Chemistry (reaction temperatures)
- Physics (thermodynamics)
- Biology (optimal growth temperatures)
- Geography (climate zones)
8. Aviation and Transportation
International aviation uses Celsius for temperature reporting, along with other metric units.
Aviation applications:
- Outside air temperature (OAT)
- Engine temperature monitoring
- Cargo hold temperature
- De-icing temperature thresholds
- Weather reporting at airports (METAR/TAF)
9. Agriculture and Horticulture
Plant growth:
- Optimal growing temperatures (species-specific)
- Germination temperatures
- Greenhouse climate control
- Frost protection thresholds (below 0°C)
Livestock:
- Barn and shelter temperature monitoring
- Incubation temperatures (poultry)
- Heat stress thresholds
Conversion Guide
Celsius to Other Temperature Units
| From | To | Formula | Example |
|---|---|---|---|
| Celsius | Fahrenheit | °F = (°C × 9/5) + 32 | 20°C = 68°F |
| Celsius | Kelvin | K = °C + 273.15 | 20°C = 293.15 K |
| Celsius | Rankine | °R = (°C + 273.15) × 9/5 | 20°C = 527.67°R |
| Celsius | Réaumur | °Ré = °C × 4/5 | 20°C = 16°Ré |
Other Units to Celsius
| From | To | Formula | Example |
|---|---|---|---|
| Fahrenheit | Celsius | °C = (°F − 32) × 5/9 | 68°F = 20°C |
| Kelvin | Celsius | °C = K − 273.15 | 293.15 K = 20°C |
| Rankine | Celsius | °C = (°R − 491.67) × 5/9 | 527.67°R = 20°C |
| Réaumur | Celsius | °C = °Ré × 5/4 | 16°Ré = 20°C |
Quick Mental Math: Celsius to Fahrenheit
Method 1: Double and add 30 (approximate, within 2-4°F):
- Multiply °C by 2
- Add 30
Examples:
- 20°C → (20 × 2) + 30 = 70°F (actual: 68°F)
- 30°C → (30 × 2) + 30 = 90°F (actual: 86°F)
- 0°C → (0 × 2) + 30 = 30°F (actual: 32°F, close!)
Method 2: Memorize key points and interpolate:
- 0°C = 32°F (freezing)
- 10°C = 50°F (add 18 for each 10°C)
- 20°C = 68°F
- 30°C = 86°F
- 37°C ≈ 98.6°F (body temperature)
Exact formula: °F = (°C × 9/5) + 32
Use our Celsius to Fahrenheit converter for instant precision.
Common Conversion Mistakes to Avoid
Mistake 1: Using the Wrong Formula
❌ Wrong: °F = °C × 1.8 (forgetting the +32)
✓ Correct: °F = (°C × 9/5) + 32 or °F = (°C × 1.8) + 32
Example:
- Wrong: 20°C = 20 × 1.8 = 36°F ❌
- Correct: 20°C = (20 × 1.8) + 32 = 68°F ✓
How to avoid: Always add 32 after multiplying. Or use our Celsius to Fahrenheit converter.
Mistake 2: Confusing Celsius with Kelvin
❌ Wrong: Thinking 0°C = 0 K
✓ Correct: 0°C = 273.15 K
Key differences:
- Kelvin: Absolute scale (no negative values), 0 K = absolute zero
- Celsius: Relative scale (can be negative), 0°C = water freezing
Easy conversion: K = °C + 273.15
Tool: Celsius to Kelvin converter
Mistake 3: Mixing Up Positive and Negative Temperatures
❌ Wrong: -40°C = 40°F
✓ Correct: -40°C = -40°F (this is the only point where both scales match!)
Common error: Forgetting that negative Celsius temperatures are MUCH colder in Fahrenheit
Examples:
- -10°C = 14°F (not -10°F or +10°F)
- -20°C = -4°F (not -20°F)
- 0°C = 32°F (not 0°F)
Mistake 4: Incorrect Degree Symbol Usage
❌ Wrong:
- 20C
- 20 degrees
- 20° degrees Celsius
✓ Correct:
- 20°C (with ° symbol before C, no space)
- 20 degrees Celsius (spelled out)
Note: The degree symbol (°) is important for clarity and professional communication.
Mistake 5: Assuming Proportional Relationships
❌ Wrong: Thinking 20°C is twice as hot as 10°C
✓ Correct: Temperature scales are not proportional from zero
Why: 0°C is not "no temperature"—that's 0 K (-273.15°C). Temperature ratios only make sense in Kelvin:
- 20°C = 293.15 K
- 10°C = 283.15 K
- Ratio: 293.15 / 283.15 = 1.035 (only 3.5% "hotter" in absolute terms)
For proportional math: Use the Kelvin scale instead.
Mistake 6: Forgetting Altitude Effects on Boiling Point
❌ Wrong: Thinking water always boils at 100°C
✓ Correct: Water boils at 100°C only at sea level (1 atm pressure)
Altitude effects:
- Sea level: 100°C (212°F)
- Denver (1,600m): ~95°C (203°F)
- La Paz (3,640m): ~88°C (190°F)
- Mount Everest (8,849m): ~71°C (160°F)
Rule: Boiling point decreases ~1°C per 300m elevation gain.
Celsius Conversion Formulas
To Fahrenheit:
To Kelvin:
To Rankine:
To Réaumur:
To Rømer:
To Newton:
To Delisle:
Frequently Asked Questions
Yes, 'Celsius' and 'Centigrade' refer to the same temperature scale. History of the name:
- 1742-1948: Called "Centigrade" (from Latin: "centum" = hundred, "gradus" = steps)
- 1948: Officially renamed "Celsius" by the 9th General Conference on Weights and Measures Reasons for the change:
- Honor Anders Celsius: Recognize the inventor's contribution
- Avoid confusion: "Centigrade" was also used for angular measurements (1/100th of a right angle), causing confusion in French and Spanish scientific literature Modern usage: "Celsius" is the official and preferred term worldwide, though "Centigrade" is still occasionally heard, especially among older generations.
Convert Celsius
Need to convert Celsius to other temperature units? Use our conversion tool.