Fathom to Shaku (Japanese) Converter
Convert fathoms to shaku with our free online length converter.
Quick Answer
1 Fathom = 6.035644 shaku
Formula: Fathom × conversion factor = Shaku (Japanese)
Use the calculator below for instant, accurate conversions.
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Fathom to Shaku (Japanese) Calculator
How to Use the Fathom to Shaku (Japanese) Calculator:
- Enter the value you want to convert in the 'From' field (Fathom).
- The converted value in Shaku (Japanese) will appear automatically in the 'To' field.
- Use the dropdown menus to select different units within the Length category.
- Click the swap button (⇌) to reverse the conversion direction.
How to Convert Fathom to Shaku (Japanese): Step-by-Step Guide
Converting Fathom to Shaku (Japanese) involves multiplying the value by a specific conversion factor, as shown in the formula below.
Formula:
1 Fathom = 6.035644 shakuExample Calculation:
Convert 10 fathoms: 10 × 6.035644 = 60.35644 shaku
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 Length conversions →What is a Fathom and a Shaku (Japanese)?
The Six-Foot Maritime Standard
The fathom is defined as exactly 6 feet in the imperial and U.S. customary measurement systems.
Precise equivalents:
- 6 feet (by definition)
- 2 yards (6 ft ÷ 3 ft/yd)
- 72 inches (6 ft × 12 in/ft)
- 1.8288 meters (exactly, using 1 ft = 0.3048 m)
- 182.88 centimeters
Historical basis: The arm span of an average man with arms fully outstretched, measured from fingertip to fingertip.
Arm Span Origins
Old English "fæthm":
- Primary meaning: To embrace, encircle with outstretched arms
- Secondary meaning: The distance between fingertips when arms are extended
Practical measurement: Sailors hauling in sounding lines (weighted ropes for measuring depth) would pull hand-over-hand, with each arm span representing one fathom. This created a natural counting method:
- Drop weighted line overboard
- Haul in, counting arm spans
- Number of arm spans = depth in fathoms
Standardization necessity: Since arm spans varied (5.5-6.5 feet typically), maritime commerce required a fixed standard. The British settled on exactly 6 feet, matching the standardized foot of 12 inches.
Nautical Charts and Depth Contours
Fathom lines: Nautical charts show depth contours (lines connecting points of equal depth) traditionally measured in fathoms.
Common contour intervals:
- 1, 2, 3, 5, 10 fathoms: Shallow coastal waters
- 20, 50, 100 fathoms: Coastal navigation
- 500, 1,000 fathoms: Deep ocean
Chart notation: Depths written as plain numbers on charts (e.g., "45") indicate 45 fathoms unless otherwise specified. Modern charts often include a note: "Depths in fathoms" or "Depths in meters."
Anchor Cable and Chain
Shackle: One "shackle" of anchor chain traditionally equals 15 fathoms (90 feet / 27.43 m) in the Royal Navy and many navies worldwide.
Anchoring depth rule: Ships typically anchor with a scope (ratio of chain length to water depth) of 5:1 to 7:1 for safety.
Example:
- Water depth: 10 fathoms (60 feet)
- Required chain: 50-70 fathoms (300-420 feet)
- That's 3.3 to 4.7 shackles
The Shaku (尺) is a traditional Japanese unit of length, forming a fundamental part of the traditional Japanese system of weights and measures known as the Shakkanhō (尺貫法). It is roughly equivalent to the English foot, although slightly shorter in its modern standardized form.
The Shaku is traditionally subdivided and multiplied decimally:
- 1 Jō (丈) = 10 Shaku
- 1 Shaku (尺) = 10 Sun (寸 - Japanese inch)
- 1 Sun (寸) = 10 Bu (分 - Japanese line)
There were historically different types of shaku, most notably the standard kanejaku (曲尺) used in carpentry and the longer kujirajaku (鯨尺) used for measuring cloth. Unless otherwise specified, "shaku" usually refers to the kanejaku.
Note: The Fathom is part of the imperial/US customary system, primarily used in the US, UK, and Canada for everyday measurements. The Shaku (Japanese) belongs to the imperial/US customary system.
History of the Fathom and Shaku (Japanese)
Ancient Maritime Practices (Pre-9th Century)
Mediterranean and Northern European sailors: Ancient mariners measured rope and depth using body-based units:
- Cubit: Elbow to fingertip (~18 inches)
- Pace: Two steps (~5 feet)
- Arm span: Outstretched arms (~6 feet)
Sounding lead: A heavy weight (lead sinker) attached to a marked line, dropped overboard to measure depth. Sailors counted arm spans as they hauled the line back aboard.
Old English Documentation (9th-11th Centuries)
Earliest references: Anglo-Saxon texts use "fæthm" for measuring rope lengths and describing distances.
Beowulf (8th-11th century): The epic poem mentions "fæthmas" in describing ocean depths and ship measurements.
Viking influence: Old Norse "faðmr" (similar arm-span measurement) influenced English usage through Viking contact and trade.
Medieval Standardization (13th-15th Centuries)
Edward I (1272-1307): English law under Edward I began standardizing measurements, including the fathom at 6 feet.
Admiralty regulations: The emerging Royal Navy needed consistent rope, sail, and depth measurements for shipbuilding and navigation.
Rope making: British rope makers sold cordage by the fathom, with standard lengths for anchor cables (120 fathoms = 1 cable length in some contexts).
Age of Exploration (15th-17th Centuries)
Navigation charts: Early nautical charts (portolan charts) began incorporating depth soundings in fathoms.
Captain James Cook (1768-1779): Cook's Pacific voyages produced meticulous charts with fathom-based depth measurements. His charts became templates for British Admiralty standards.
Example - HMS Endeavour soundings: Cook's logs record depths like "15 fathoms, sandy bottom" or "No bottom at 100 fathoms" (indicating depths exceeding 600 feet).
British Admiralty Charts (19th Century)
Hydrographic Office (founded 1795): The British Admiralty Hydrographic Office systematized global nautical chart production, standardizing fathoms for depth.
Matthew Fontaine Maury (1806-1873): American oceanographer Maury collaborated with the British to create standardized depth charts using fathoms, mapping ocean currents and depths.
Cable-laying expeditions: Transatlantic telegraph cable projects (1850s-1860s) required precise fathom-based depth surveys. HMS Agamemnon and USS Niagara charted the Atlantic floor in fathoms before laying the 1858 cable.
U.S. Navy Adoption (19th-20th Centuries)
Inherited British standards: The U.S. Navy adopted British maritime practices, including fathom-based charts and anchor cable measurements.
U.S. Coast and Geodetic Survey: Founded in 1807 (originally "Survey of the Coast"), it produced nautical charts in fathoms for American waters.
World War II: Submarine warfare and amphibious operations relied heavily on fathom-based depth charts. USS submarines operated in waters charted in fathoms.
Metrication Movement (20th Century-Present)
International Hydrographic Organization (IHO, founded 1921): Recommended global adoption of metric system for nautical charts.
Gradual transition:
- 1970s-1980s: Most nations began publishing new charts in meters
- UK Admiralty: Converted most charts to meters by the 1990s
- U.S. NOAA: Many American charts still use fathoms, particularly for coastal waters
Mixed usage today: Modern electronic chart systems (ECDIS) allow display in either fathoms or meters, accommodating mariners accustomed to either system.
The Shaku originated from the Chinese Chi (尺), introduced to Japan likely between the 3rd and 6th centuries AD. Like its Chinese counterpart, the length of the Shaku varied considerably across different historical periods and regions in Japan.
- Early Adoption: Early Japanese measurements were heavily influenced by Chinese standards, but the length of the Shaku began to diverge over time.
- Edo Period (1603–1868): Different standards coexisted, including the kanejaku (carpenter's shaku) and the kujirajaku (cloth shaku, literally "whale shaku," possibly referring to rulers made from whale baleen). The kanejaku became the more common standard for general measurement.
- Meiji Restoration (1868 onwards): Japan began modernizing and standardizing its systems. In 1891, the Weights and Measures Act defined the standard Shaku (kanejaku) legally in relation to the metric system as exactly 10/33 of a meter. This aimed to provide a precise conversion factor while preserving the traditional unit. The kujirajaku was defined as 1.25 times the kanejaku (i.e., 12.5/33 of a meter).
- Metrication: Japan officially adopted the metric system in 1951, and its use became mandatory for most official and commercial transactions by 1966. However, the Shaku and other Shakkanhō units remain in use in specific traditional fields.
Common Uses and Applications: fathoms vs shaku
Explore the typical applications for both Fathom (imperial/US) and Shaku (Japanese) (imperial/US) to understand their common contexts.
Common Uses for fathoms
1. Nautical Charts and Hydrography
Depth soundings: Nautical charts mark depths in fathoms, particularly on U.S. and older British charts.
Contour lines: Lines connecting equal depths (e.g., the 10-fathom line) help mariners avoid shallow areas.
Chart abbreviations:
- fms: Fathoms
- fm: Fathom
- No bottom at 100 fms: Depth exceeds 100 fathoms (600 feet)
2. Anchoring and Mooring
Anchor scope: Mariners calculate how much anchor chain to deploy based on water depth in fathoms.
Rule of thumb: Deploy 5-7 times the water depth in calm conditions, 7-10 times in storms.
Example:
- Depth: 8 fathoms
- Calm weather scope (5:1): 40 fathoms of chain
- Storm scope (10:1): 80 fathoms of chain
3. Commercial Fishing
Net depth: Fishermen describe trawl net depths in fathoms.
Example: "Running trawl at 50 fathoms" (300 feet deep)
Fishing line: Deep-sea fishing lines measured in fathoms to target specific depths.
4. Recreational Boating and Diving
Depth sounders: Many recreational boat depth finders display fathoms (though meters and feet are increasingly common).
Dive planning: Divers reference depth in fathoms on nautical charts when planning dive sites.
5. Submarine Operations
Periscope depth: Submarines traditionally use fathoms for depth control.
Example: "Dive to 20 fathoms" (120 feet)
Historical note: WWII submarine logs recorded depths in fathoms; modern submarines use meters.
6. Maritime Literature and Tradition
Nautical expressions:
- "To fathom something" = to understand its depth (metaphorically)
- "Unfathomable" = too deep to measure or comprehend
Sailing instructions: Traditional pilot books use fathoms for approach depths and anchorage recommendations.
When to Use shaku
While the metric system is standard in Japan, the Shaku persists in several areas:
- Traditional Japanese Architecture and Carpentry: The kanejaku is still widely used for measurements in building temples, shrines, traditional houses, and making furniture. Architectural modules like the ken (間) are often based on the Shaku. Japanese woodworking tools are often sized or marked in Shaku and Sun.
- Kimono and Traditional Clothing: The kujirajaku is the standard unit for measuring cloth width (tanmono) and dimensions when making kimonos and yukatas.
- Traditional Crafts: Used in making items like tatami mats, shōji screens, and other traditional crafts where historical dimensions are important.
- Musical Instruments: The length of traditional Japanese instruments, notably the shakuhachi (尺八) flute, is measured in Shaku and Sun (its name literally means "1.8 shaku").
- Martial Arts: Some traditional martial arts (koryū budō) may use Shaku-based measurements for weapon lengths (e.g., jō, bō) or stance dimensions.
- Gardening and Landscaping: Traditional Japanese garden design sometimes employs Shaku-based proportions.
- Historical and Cultural Context: Essential for understanding dimensions in historical texts, art, and artifacts.
Additional Unit Information
About Fathom (fath)
How many feet are in a fathom?
Exactly 6 feet = 1 fathom.
This is the defining relationship. The fathom was standardized to 6 feet during medieval English measurement standardization.
How many meters are in a fathom?
1 fathom = 1.8288 meters (exactly).
This conversion uses the international foot definition: 1 foot = 0.3048 meters (exactly).
Calculation: 6 feet × 0.3048 m/ft = 1.8288 m
Is the fathom an SI unit?
No, the fathom is not an SI unit.
It belongs to the imperial and U.S. customary systems. The SI unit of length is the meter.
International usage: The International Hydrographic Organization recommends meters for nautical charts, but fathoms remain legal and common in U.S. and some British waters.
Is the fathom still commonly used today?
Yes, in specific maritime contexts, especially in the United States.
Still common:
- U.S. NOAA nautical charts (many coastal charts)
- Recreational boating in the U.S.
- Commercial fishing fleets
- Maritime tradition and literature
Declining usage:
- International shipping (uses meters)
- Most modern navies (switched to meters)
- New chart production (increasingly metric)
Result: Fathoms persist in American waters and traditional maritime communities but are gradually being replaced by meters in international contexts.
Where does the word "fathom" come from?
From Old English "fæthm" (outstretched arms, embrace).
Etymology:
- Proto-Germanic: *faþmaz (embrace, armful)
- Old English: fæthm (span of outstretched arms)
- Middle English: fadme, fathme
- Modern English: fathom
Original meaning: The distance between fingertips when a person extends both arms horizontally—roughly 6 feet for an average man.
Verb form: "To fathom" originally meant "to measure depth with outstretched arms," later metaphorically "to comprehend deeply" (exploring the depths of understanding).
Why are anchor chains measured in shackles, not fathoms?
Both are used, but shackles are standard for large vessels.
Shackle definition: 1 shackle = 15 fathoms = 90 feet = 27.43 meters
Reason: Anchor chains are physically connected with shackle links every 15 fathoms. These physical shackles allow disconnection for maintenance and provide visual/tactile markers when deploying chain.
Usage:
- Small vessels: Anchor chain length in fathoms
- Large vessels and navies: Anchor chain length in shackles
Example: "Deploy 5 shackles" = 75 fathoms = 450 feet of chain
How deep is "full fathom five"?
5 fathoms = 30 feet = 9.144 meters.
Shakespeare's The Tempest: Ariel's song describes a drowned man lying at the bottom, 5 fathoms below the surface.
Context: 30 feet is deep enough that:
- Surface light barely reaches the body
- Free diving without equipment is challenging
- The body would be difficult to recover without specialized equipment
This depth creates the eerie, unreachable quality of Ariel's description.
Can I convert my depth sounder from fathoms to meters?
Yes, most modern depth sounders (fishfinders, chartplotters) allow unit selection.
Typical options:
- Feet
- Fathoms
- Meters
How to change (general steps):
- Access settings menu
- Find "Units" or "Depth Units"
- Select preferred unit (fathoms, feet, or meters)
- Save settings
Check manual: Specific instructions vary by manufacturer (Garmin, Lowrance, Raymarine, Furuno, etc.).
What's the difference between fathoms and cable lengths?
Both are nautical length units, but they measure different things:
Fathom:
- 6 feet / 1.8288 meters
- Primarily for depth measurement
Cable length:
- UK: 608 feet = 185.3 meters (1/10 nautical mile)
- US (historical): 720 feet = 219.5 meters (120 fathoms)
- Primarily for horizontal distance (anchor cable, ship-to-ship spacing)
Confusion: The term "cable" sometimes referred to 100 or 120 fathoms of anchor cable, but the standardized "cable length" unit differs from this.
Do submarines still use fathoms?
Historically yes, but modern submarines use meters.
World War II era: U.S. and British submarines recorded depths in fathoms (e.g., "Dive to 50 fathoms").
Modern practice:
- U.S. Navy: Switched to feet and meters for submarine operations
- International: Nearly all modern navies use meters
Reason for change: International standardization, digital instrumentation, and NATO interoperability drove metrication.
About Shaku (Japanese) (shaku)
How long is a Shaku?
The length depends on the context (historical vs. modern, type of shaku):
- Modern Standardized Kanejaku (since 1891):
- Exactly 10/33 meters (m)
- Approximately 0.30303 meters
- Approximately 30.303 centimeters (cm)
- Approximately 11.93 inches (in)
- Approximately 0.994 feet (ft)
- Modern Standardized Kujirajaku:
- Exactly 12.5/33 meters (m) (1.25 times the kanejaku)
- Approximately 0.37879 meters
- Approximately 37.879 centimeters (cm)
- Approximately 14.91 inches (in)
- Approximately 1.243 feet (ft)
- Historical Shaku: Varied significantly, often differing from the modern standard.
What are the subdivisions and multiples of the Shaku?
The system is decimal:
- Subdivisions: 1 Shaku = 10 Sun (寸); 1 Sun = 10 Bu (分).
- Multiples: 1 Jō (丈) = 10 Shaku. Another related unit is the Ken (間), traditionally 6 Shaku, though its length could vary.
Is it the same as the Chinese Chi?
No. Although the Japanese Shaku originated from the Chinese Chi (both written with the character 尺), they evolved independently and have different standardized lengths today.
- Modern Japanese Shaku (kanejaku): 10/33 meters (≈ 0.303 m)
- Modern Chinese Chi: 1/3 meter (≈ 0.333 m) The Shaku is noticeably shorter than the modern Chi.
What is the difference between kanejaku and kujirajaku?
They are two distinct traditional Shaku units:
- Kanejaku (曲尺): The "carpenter's shaku," used for general measurement, architecture, and woodworking. Standardized at 10/33 meters. This is the default meaning of "Shaku."
- Kujirajaku (鯨尺): The "cloth shaku" or "whale shaku," used primarily for measuring cloth, especially for kimonos. It is longer than the kanejaku, standardized at 12.5/33 meters (exactly 1.25 times the kanejaku).
Is the Shaku an SI unit?
No, the Shaku is not an SI unit. It is a traditional Japanese unit belonging to the Shakkanhō system. The SI base unit for length is the meter (m).
Is the Shaku still used today?
Yes, although Japan officially uses the metric system (SI units) for most purposes, the Shaku (both kanejaku and kujirajaku) continues to be used in specific traditional fields:
- Traditional architecture and carpentry.
- Kimono making and textile measurement.
- Other traditional crafts.
- Musical instrument making (e.g., shakuhachi).
- Historical and cultural studies. It is generally not used in everyday commerce or scientific contexts.
Conversion Table: Fathom to Shaku (Japanese)
| Fathom (fath) | Shaku (Japanese) (shaku) |
|---|---|
| 0.5 | 3.018 |
| 1 | 6.036 |
| 1.5 | 9.054 |
| 2 | 12.071 |
| 5 | 30.178 |
| 10 | 60.356 |
| 25 | 150.891 |
| 50 | 301.782 |
| 100 | 603.564 |
| 250 | 1,508.911 |
| 500 | 3,017.822 |
| 1,000 | 6,035.644 |
People Also Ask
How do I convert Fathom to Shaku (Japanese)?
To convert Fathom to Shaku (Japanese), enter the value in Fathom in the calculator above. The conversion will happen automatically. Use our free online converter for instant and accurate results. You can also visit our length converter page to convert between other units in this category.
Learn more →What is the conversion factor from Fathom to Shaku (Japanese)?
The conversion factor depends on the specific relationship between Fathom and Shaku (Japanese). 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 Shaku (Japanese) back to Fathom?
Yes! You can easily convert Shaku (Japanese) back to Fathom by using the swap button (⇌) in the calculator above, or by visiting our Shaku (Japanese) to Fathom converter page. You can also explore other length conversions on our category page.
Learn more →What are common uses for Fathom and Shaku (Japanese)?
Fathom and Shaku (Japanese) are both standard units used in length measurements. They are commonly used in various applications including engineering, construction, cooking, and scientific research. Browse our length converter for more conversion options.
For more length conversion questions, visit our FAQ page or explore our conversion guides.
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Other Length Units and Conversions
Explore other length units and their conversion options:
- Meter (m) • Fathom to Meter
- Kilometer (km) • Fathom to Kilometer
- Hectometer (hm) • Fathom to Hectometer
- Decimeter (dm) • Fathom to Decimeter
- Centimeter (cm) • Fathom to Centimeter
- Millimeter (mm) • Fathom to Millimeter
- Inch (in) • Fathom to Inch
- Foot (ft) • Fathom to Foot
- Yard (yd) • Fathom to Yard
- Mile (mi) • Fathom to Mile
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 US standards for length measurements
Bureau International des Poids et Mesures — International System of Units official documentation
Last verified: February 19, 2026