Fathoms to Millimeters (ftm to mm)

1 fathom equals 1,828.8 millimeters exactly.

1 fathom = 1,828.8 millimeters

How to convert fathoms to millimeters

To convert fathoms to millimeters, multiply the number of fathoms by 1,828.8. This factor is exact. To go the other way, multiply millimeters by 0.0005468066492 (rounded).

millimeters = fathoms × 1,828.8

Example: 10 fathoms = 18,288 millimeters.

About these units

Fathom (ftm)

NauticalTraditional unit (still used in some regions)

6 feet (1.8288 m), traditionally the span of a man's outstretched arms. Still used for water depth on nautical charts in some countries.

Old English fæðm meant a pair of outstretched arms, and the word gave English its fathom. That is the origin of the measure: the span between the fingertips of a man with his arms spread wide, roughly the height of a person. Because bodies differ, the fathom was not fixed for centuries. Merchant ships are recorded as using about five and a half feet, and fishing boats five or seven, until the length was settled at six feet in the nineteenth century.

Sailors counted in fathoms because a hand sounding line carried marks at fathom intervals, so the depth could be read off when the weight touched bottom. Water shallower than 100 fathoms was said to be in soundings. Anchor chain and fishing line were also sold and counted in fathoms. The figure used here is exactly six feet, or 1.8288 m, which makes two yards one fathom. Most charts today show metres, though some national charts still print fathoms.

1 fathom = 1.8288 meters (exactly).

Sources: Wikipedia: Fathom; NIST SP 811, Appendix B.8 (length conversion factors)

Millimeter (mm)

Metric (SI)Current unit

One thousandth of a meter. Used in engineering, manufacturing and rainfall measurement.

Carl Friedrich Gauss put the millimeter at the base of his 1832 proposal for absolute units, pairing it with the milligram and the second, although the centimeter-based CGS system later won out among scientists. The name combines the metric prefix milli-, from the Latin for one thousand, with the meter. Since 1983 a millimeter has been tied to the speed of light: it is the distance light covers in 1/299,792,458,000 of a second.

Millimeters are the language of fine mechanical work. Standard rulers are divided into them, digital calipers commonly read to 0.01 mm, and mechanical pencil leads come in 0.5 and 0.7 mm. Copy paper is about 0.1 mm thick, and a thin hair, at 0.02 to 0.04 mm across, is close to the smallest thing the naked eye can see. A wave with a frequency of 300 GHz has a wavelength of 1 mm. An inch is exactly 25.4 mm. One trap for readers in the United States is that mil there traditionally means a thousandth of an inch, not a millimeter.

1 millimeter = 0.001 meters (exactly).

Sources: Wikipedia: Millimetre; Wikipedia: Centimetre-gram-second system of units; NIST Guide to the SI, Appendix B.8: conversion factors

Related conversions

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