Instantly Convert Fathoms ↔ Metres — Both Directions
Convert fathoms to metres (fathom → m) or metres to fathoms (m → fathom) instantly. Get the exact conversion with formula breakdown, reference table, and real-world examples — all free, no sign-up needed.
The fathom is an ancient nautical unit of depth, while the metre is the modern SI standard. Our converter handles both directions instantly and accurately using the exact internationally defined conversion factor of 1 fathom = 1.8288 metres.
The fathom is a unit of length used primarily to measure water depth in nautical contexts. It originates from the Old English word fæthm, meaning "outstretched arms." One fathom equals 6 feet or exactly 1.8288 metres. It remains in use by mariners, divers, and hydrographers worldwide, particularly on nautical charts and depth soundings.
The metre (m) is the base unit of length in the International System of Units (SI) and is used across most of the world. Since 1983, the metre has been defined as the distance light travels in a vacuum in 1/299,792,458 of a second. In depth measurement, metres are the international standard used by oceanographers, hydrographers, and scientific publications globally.
The exact conversion factor is 1 fathom = 1.8288 metres. This is derived from: 1 fathom = 6 feet, and 1 foot = exactly 0.3048 metres, so 6 × 0.3048 = 1.8288. For the reverse, 1 metre = 0.54681 fathoms (1 ÷ 1.8288). All conversions on this page use these exact values.
Choose a direction, enter your value, and get an instant conversion
Figure: Visual comparison of 1 fathom, 1 metre, and 6 feet (depth scale)
The conversion between fathoms and metres uses an exact mathematical factor derived from the international definition of the foot. Since 1 fathom = 6 feet and 1 foot = exactly 0.3048 metres, the full conversion is: 6 × 0.3048 = 1.8288 metres per fathom. This is not an approximation — both formulas below are exact.
The table below lists commonly needed fathom-to-metre conversions for nautical, diving, and oceanographic use. All values use the exact factor of 1 fathom = 1.8288 m. For metres to fathoms, divide the metre value by 1.8288 or use the converter above. You can also explore our unit converters for other conversions.
| Fathoms | Metres (m) | Feet (ft) | Centimetres (cm) | Common Context |
|---|---|---|---|---|
| 0.5 fathom | 0.9144 m | 3 ft | 91.44 cm | Very shallow reef |
| 1 fathom | 1.8288 m | 6 ft | 182.88 cm | Shallow swimming depth |
| 2 fathoms | 3.6576 m | 12 ft | 365.76 cm | Snorkelling depth |
| 3 fathoms | 5.4864 m | 18 ft | 548.64 cm | Shallow scuba dive |
| 5 fathoms | 9.144 m | 30 ft | 914.4 cm | Recreational dive limit (beginner) |
| 10 fathoms | 18.288 m | 60 ft | 1828.8 cm | Standard recreational scuba depth |
| 20 fathoms | 36.576 m | 120 ft | 3657.6 cm | Advanced recreational diving |
| 30 fathoms | 54.864 m | 180 ft | 5486.4 cm | Technical diving range |
| 50 fathoms | 91.44 m | 300 ft | 9144 cm | Deep technical dive |
| 100 fathoms | 182.88 m | 600 ft | 18288 cm | Deep sea / submarine depth |
| 200 fathoms | 365.76 m | 1200 ft | 36576 cm | Edge of continental shelf |
| 500 fathoms | 914.4 m | 3000 ft | 91440 cm | Deep ocean zone |
| 1000 fathoms | 1828.8 m | 6000 ft | 182880 cm | Abyssal zone entry |
| 3000 fathoms | 5486.4 m | 18000 ft | 548640 cm | Deep abyssal ocean |
The table below shows common metre values converted to fathoms. All values use the exact factor of 1 m = 0.54681 fathoms (= 1 ÷ 1.8288). This is especially useful when reading scientific depth data in metres and needing to reference nautical charts in fathoms.
| Metres (m) | Fathoms | Feet (ft) | Inches (in) |
|---|---|---|---|
| 1 m | 0.5468 fathoms | 3.2808 ft | 39.37 in |
| 2 m | 1.0936 fathoms | 6.5617 ft | 78.74 in |
| 5 m | 2.7340 fathoms | 16.404 ft | 196.85 in |
| 10 m | 5.4681 fathoms | 32.808 ft | 393.70 in |
| 20 m | 10.936 fathoms | 65.617 ft | 787.40 in |
| 30 m | 16.404 fathoms | 98.425 ft | 1181.1 in |
| 50 m | 27.340 fathoms | 164.04 ft | 1968.5 in |
| 100 m | 54.681 fathoms | 328.08 ft | 3937.0 in |
| 200 m | 109.361 fathoms | 656.17 ft | 7874.0 in |
| 500 m | 273.403 fathoms | 1640.4 ft | 19685 in |
| 1000 m (1 km) | 546.807 fathoms | 3280.8 ft | 39370 in |
The fathom-to-metre conversion is essential across a range of maritime, scientific, and recreational activities. Here are the most common real-world scenarios where this conversion is needed.
Traditional nautical charts — especially older British Admiralty charts — display water depth in fathoms. Modern international charts increasingly use metres per the International Hydrographic Organization (IHO) standard. Mariners frequently need to convert fathom-based soundings to metres to cross-reference GPS systems and modern electronic navigation tools.
Dive tables, dive computers, and dive site guides may express depth in either fathoms or metres depending on the country of origin. US dive guides often use fathoms or feet, while international and European standards use metres. A diver planning a 10-fathom dive needs to know that equals 18.288 metres — well within recreational limits.
Scientific literature, ocean depth surveys, and bathymetric data are published in both fathoms and metres depending on era and country of publication. Converting historical depth records (in fathoms) to modern SI units (metres) is routine in oceanographic research. The average ocean depth is approximately 2,000 fathoms = 3,657.6 metres.
Deep-sea fishing line depth, fish finders, and fishing charts often display depth in fathoms — particularly in the United States and United Kingdom. Anglers targeting specific depth zones (e.g., a 5-fathom ledge = 9.144 m) need to convert these values when using modern metric sonar equipment or when following international fishing regulations.
When anchoring a vessel, sailors must know the water depth to set the correct amount of anchor chain (scope). Older sailing manuals and harbour guides list anchorage depths in fathoms. For example, a 3-fathom anchorage equals 5.4864 metres — important for calculating safe scope ratios and avoiding anchor drag.
The fathom appears frequently in classic maritime literature, historical records, and Shakespeare's works (most famously: "Full fathom five thy father lies" from The Tempest — 5 fathoms = 9.144 metres). Historians, researchers, and literature students converting archaic depth measurements to modern metres regularly use this conversion.
The National Oceanic and Atmospheric Administration (NOAA) provides authoritative data on ocean depths, nautical measurements, and hydrographic standards used by mariners worldwide.
Visit NOAA →The Bureau International des Poids et Mesures (BIPM) is the international body responsible for defining SI units including the metre. Their official resources cover unit definitions and conversion standards used globally.
Visit BIPM →The International Hydrographic Organization (IHO) sets global standards for nautical charts and depth measurement, including the transition from fathoms to metres on official maritime charts worldwide.
Visit IHO →PADI is the world's leading diver training organisation. Their depth standards and dive table guides use both metres and feet, making fathom conversions relevant for divers training across different regions.
Visit PADI →