Cubits to Millimeters (cbt to mm)

1 cubit equals 457.2 millimeters exactly.

1 cubit = 457.2 millimeters

How to convert cubits to millimeters

To convert cubits to millimeters, multiply the number of cubits by 457.2. This factor is exact. To go the other way, multiply millimeters by 0.002187226597 (rounded).

millimeters = cubits × 457.2

Example: 10 cubits = 4,572 millimeters.

Approximate value. Standards for the cubit varied by place and period, so this converter uses the most commonly cited value. Treat results as estimates, not exact figures.

About these units

Cubit (cbt)

Medieval EnglishHistorical unit (no longer in standard use)Approximate value

Traditionally the length from the elbow to the tip of the middle finger. The common English cubit is taken as 18 inches (45.72 cm); ancient cubits ranged from about 44 to 53 cm.

From the Latin cubitum, meaning elbow, the cubit was the forearm measured from the elbow to the fingertips. English use tied it to roughly 18 inches, or 45.72 cm. Such a hand-and-arm measure is the same idea that produced the ell, which Wikipedia describes as originally a cubit.

No single value ever governed it. Wikipedia lists most ancient cubits between 44.4 and 52.92 cm, from the Roman cubitus of about 444 mm, which Vitruvius set at one and a half Roman feet, to the Egyptian royal cubit near 523 to 529 mm. Medieval Islamic cubits ranged far wider still.

The English ell eventually settled at 45 inches, one and a quarter yards, while the cubit faded from commerce. A trace survives in hedgelaying, where a forearm of about 18 inches sets the spacing of stakes. The figure used here is the 18 inch English cubit.

1 cubit = 0.4572 meters (approximately).

Sources: Wikipedia: Cubit; Wikipedia: Ell

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

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