📏 ft to ftm — Foot to Fathom Converter

Convert length and distance units — meters, feet, inches, kilometers, miles, light years and more.

1 unit =
From
To
Formula 1 ft = 0.166667 ftm
UnitNameValue
0.001 ft0.000166667 ftm
0.01 ft0.00166667 ftm
0.1 ft0.0166667 ftm
1 ft0.166667 ftm
5 ft0.833333 ftm
10 ft1.66667 ftm
50 ft8.33333 ftm
100 ft16.6667 ftm
1000 ft166.667 ftm

How to convert Foot to Fathom

Multiply the number of Foots by 0.166667 to get Fathoms. Formula: ftm = ft × 0.166667. Example: 10 ft × 0.166667 = 1.66667 ftm. To reverse, divide Fathoms by 0.166667 to get Foots.

Worked examples

Example 1
1 ft × 0.166667 = 0.166667 ftm
1 Foot equals 0.166667 Fathom.
Example 2
5 ft × 0.166667 = 0.833333 ftm
5 Foot equals 0.833333 Fathom.
Example 3
10 ft × 0.166667 = 1.66667 ftm
10 Foot equals 1.66667 Fathom.
Example 4 — reverse
1 ftm = 6 ft
To convert back from Fathom to Foot, divide by 0.166667 or use the swap button above.

Foot to Fathom — reference table

Foot (ft)Fathom (ftm)
0.001 ft0.000166667 ftm
0.01 ft0.00166667 ftm
0.1 ft0.0166667 ftm
0.5 ft0.0833333 ftm
1 ft0.166667 ftm
2 ft0.333333 ftm
5 ft0.833333 ftm
10 ft1.66667 ftm
20 ft3.33333 ftm
50 ft8.33333 ftm
100 ft16.6667 ftm
250 ft41.6667 ftm
500 ft83.3333 ftm
1000 ft166.667 ftm
10000 ft1666.67 ftm

Quick conversion tips

1
Multiply by 0.166667

To convert Foot to Fathom, multiply by 0.166667. Example: 10 ft = 1.66667 ftm

2
Reverse: divide by 0.166667

To convert Fathom back to Foot, divide by 0.166667 (multiply by 6). Use the swap button above.

3
Round number check

Start with 100 Foots = 16.6667 ftm as your reference point. Scale up or down from there.

Where foot to fathom conversion is used

US nautical navigation

American boaters and naval officers use both feet (for vessel dimensions and bridge clearance) and fathoms (for water depth from charts) simultaneously. Converting between them is a core competency in US coastal navigation.

Anchor chain sizing

1 fathom = 6 feet exactly — the cleanest ratio in maritime measurement. Sailors sizing anchor rodes (in feet or yards) against chart depths (in fathoms) use this conversion constantly when selecting and deploying anchoring equipment.

Historic US naval records

US Navy logs and ship surveys from the 18th–20th centuries record vessel draughts in feet and water depths in fathoms. Naval historians and archivists convert between the two when indexing and cross-referencing operational records.

Fishing industry

Commercial fishing vessels in the US set net depth in fathoms using chart data, while net dimensions and gear specifications use feet — fishermen and equipment manufacturers convert between the two for every gear configuration.

Underwater construction

Offshore platform foundations are engineered in feet for structural calculations while installation depths are specified in fathoms from admiralty charts — marine engineers convert between the two in every offshore foundation design.

Dive planning

US recreational divers using older dive tables in fathoms convert to feet for modern dive computers. The 1:6 ratio makes mental calculation straightforward — a 10-fathom dive is 60 feet, matching the common recreational diving limit.

Frequently asked questions

1 Foot equals 0.166667 Fathoms. Multiply any Foot value by 0.166667 to get Fathoms.
10 Foots equals 1.66667 Fathoms. (10 × 0.166667 = 1.66667)
100 Foots equals 16.6667 Fathoms. (100 × 0.166667 = 16.6667)
Divide Fathom by 0.166667 to get Foots. Or multiply by 6. Use the swap button on the converter above for instant reverse conversion.
Formula: ftm = ft × 0.166667. Example: 5 ft × 0.166667 = 0.833333 ftm.
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About Foot and Fathom

Foot (ft)

The Foot is a unit of Length measurement (symbol: ft). 1 ft = 0.166667 ftm. Used in scientific and practical Length measurement applications.

Fathom (ftm)

The Fathom is a unit of Length measurement (symbol: ftm). It is part of an internationally recognised measurement system used alongside the Foot.

History & origin

The foot is one of humanity's oldest measurement units, used by ancient Egyptians, Greeks, and Romans — each with slightly different values. The English statute foot was standardised at 12 inches in 1305 under King Edward I. Its definition was refined multiple times over centuries, finally fixed as exactly 0.3048 metres under the International Yard and Pound Agreement of 1959, signed by the US, UK, Canada, Australia, and South Africa. Today the foot remains official in the US, UK (for road distances and aviation), and international aviation worldwide.

The fathom derives from the Old English 'fæthm', meaning the span of outstretched arms — roughly 6 feet or 1.8 metres. It was the primary depth measurement unit used by mariners for millennia, recorded in the Bible and used by ancient Greeks. Samuel Pepys referenced fathoms in 17th-century naval logs. The word 'fathom' also entered English as a verb meaning to understand something deeply — from the idea of plumbing the depths. Despite metrication, fathoms remain on admiralty charts and in nautical tradition worldwide.

Common use: Foot to Fathom conversion is needed when working with international standards, scientific publications, or reference materials that use different unit systems for Length measurement.