Convert Fathom to Perch
Convert fathoms to perches instantly. 1 fathom = 0.3636363636 perch — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Perch to Fathom converter for the reverse conversion.
Units explained
Fathom
A fathom is an Imperial unit of length equal to 6 feet or exactly 1.8288 meters. It is used almost exclusively for measuring water depth in maritime contexts.
The fathom derives from the Old English word fæthm, meaning "the embracing arms" — the distance between the fingertips of a person's outstretched arms. Standardized at 6 feet in English maritime tradition.
Fathoms are used in nautical depth charts, scuba diving, oceanography, and maritime literature. Despite metrication efforts, fathoms remain common in English-language nautical charts and recreational diving.
Old English origin (predating 1066); standardized at 6 feet by English maritime tradition; fixed at 1.8288 m exactly via the 1959 International Yard and Pound Agreement.
Perch
A perch is an Imperial unit of length identical to the rod — 16.5 feet (about 5.03 m). The names 'rod', 'perch', and 'pole' all refer to the same surveying unit and differ only by regional preference.
Like the rod, the perch derives from medieval English land-surveying. The name 'perch' was particularly common in legal land descriptions in Ireland and parts of the UK.
Perches appear in legacy land descriptions in Ireland, the UK, and historical US documents. Modern usage is rare.
Medieval English surveying origin; identical to the rod since 1620; became exact via the 1959 International Yard and Pound Agreement.
Fathom to Perch conversion formula
The relationship between fathoms and perches:
To convert fathoms to perches, multiply the value in fathoms by 0.3636363636. To reverse, multiply perches by 2.75.
How to use this converter
Type a value into the calculator. The result in perches updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Perch to Fathom converter for the reverse direction.
Step-by-step: convert fathoms to perches
- Write down the value in fathoms (ftm).
- Multiply that value by the factor 0.3636363636.
- The product is the equivalent value in perches (perch).
- To reverse, multiply the perch value by 2.75.
Worked examples
Example 1 — Convert 1 ftm to perch:
1 × 0.3636363636 = 0.3636363636 perch
Example 2 — Convert 100 ftm to perch:
100 × 0.3636363636 = 36.3636363636 perch
Real-world example — Maritime depth conversion
A 10-fathom sounding depth converts cleanly into perches. Recreational divers and sailors translate between the two units whenever they read legacy charts against modern depth-sounder displays.
10 ftm × 0.3636363636 = 3.6363636364 perch
Real-world example — Reference scenario in case of fallback
Conversion between human-scale length units is the everyday workflow of architecture, athletics, and apparel design — three of the most common contexts that span metric and imperial systems.
1 ftm × 0.3636363636 = 0.3636363636 perch
Real-world example — Adult height conversion
A 1.8-fathom-tall person measures a value in perches that converts the height to the unit favoured by American forms, schools, or driver's licences. This is daily routine for anyone living between metric and imperial systems.
1.8 ftm × 0.3636363636 = 0.6545454545 perch
Fathom to Perch conversion table
Standard reference values for converting fathoms to perches:
| Fathom [ftm] | Perch [perch] |
|---|---|
| 0.01 | 0.0036363636 |
| 0.1 | 0.0363636364 |
| 1 | 0.3636363636 |
| 2 | 0.7272727273 |
| 3 | 1.0909090909 |
| 4 | 1.4545454545 |
| 5 | 1.8181818182 |
| 10 | 3.6363636364 |
| 20 | 7.2727272727 |
| 30 | 10.9090909091 |
| 40 | 14.5454545455 |
| 50 | 18.1818181818 |
| 100 | 36.3636363636 |
| 500 | 181.8181818182 |
| 1000 | 363.6363636364 |
Frequently asked questions
How many perches is 1 fathom?
How do I convert fathoms to perches?
How do I convert perches back to fathoms?
How many perches is 100 fathoms?
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Metric / SI (7 units)
Imperial / US Customary (26 units)
Nautical (1 units)
Sources & references
Conversion factor (1 ftm = 0.3636363636 perch) verified against the following authoritative sources:
- BIPM — The International System of Units (SI Brochure 9th ed.)
Official BIPM publication defining the seven SI base units (including the meter) and the rules for their use. The global authority on units of measurement.
- NIST — Guide to the SI
US National Institute of Standards and Technology reference covering the SI base and derived units with definitions and usage rules for US technical practice.
- NIST Special Publication 811 — Guide for the Use of the International System of Units
Detailed NIST guide covering exact conversion factors between SI and US customary units along with formatting and rounding conventions.
- NIST — Refinement of values for the yard and pound (Federal Register 1959)
The treaty (signed by US
- International Hydrographic Organization — Resolution on the Nautical Mile
International authority that standardised the nautical mile at exactly 1852 m in 1929 — the value adopted worldwide for sea and air navigation.