Roman Cubits to Inches (cubitum to in)

1 Roman cubit equals 17.48031496 inches (rounded).

1 Roman cubit = 17.48031496 inches

How to convert Roman cubits to inches

To convert Roman cubits to inches, multiply the number of Roman cubits by 17.48031496. The factor is rounded to 10 significant digits. To go the other way, multiply inches by 0.05720720721 (rounded).

inches = Roman cubits × 17.48031496

Example: 10 Roman cubits = 174.8031496 inches.

Approximate value. Standards for the Roman 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

Roman Cubit (cubitum)

Ancient RomanHistorical unit (no longer in standard use)Approximate value

One and a half Roman feet, about 44.4 cm.

Cubitum was the Latin word for elbow, and it came from a verb meaning to lie down or recline, the root of the English cubit. Roman writers such as Vitruvius defined it as one and a half Roman feet, or six palm widths, which gives about 444 mm. That is the figure used here. It was meant to span roughly the length of the forearm from the elbow to the fingertips.

Compared with other ancient cubits it was short. The Egyptian royal cubit survives on rods measuring about 523 to 529 mm, and Wikipedia says ancient cubits generally ranged from about 44.4 to 52.9 cm, so the Roman one sits at the bottom of that range. Romans also used a separate, longer ulna of about 120 cm. In a modern setting the Roman cubit is a little over 17 inches.

1 Roman cubit = 0.444 meters (approximately).

Sources: Wikipedia: Cubit; Wikipedia: Ancient Roman units of measurement

Inch (in)

US & ImperialCurrent unit

1/12 of a foot. Defined as exactly 25.4 millimeters since 1959, when the US and Commonwealth countries agreed a common international inch.

Latin uncia, meaning one-twelfth, is the root of both inch and ounce, and it passed into Old English as ynce. Roman measurers divided their foot into twelve unciae, and the English inch kept that twelfth. After 1066 an inch was reckoned as three barleycorns, and a 1324 statute attributed to Edward II spelled out the definition as three grains of barley, dry and round, placed end to end lengthwise. For centuries the inch was simply a twelfth of a foot, or a thirty-sixth of a yard, and the US and UK each kept their own copy of the standard yard.

Those copies differed slightly until the 1959 international agreement fixed the yard at exactly 0.9144 meter, which made the inch exactly 25.4 millimeters. The US adopted it in 1959 and the UK ratified it in 1963, effective 1964. Today the inch is still the customary unit in the United States and Canada, and the UK keeps it on road signs. Worldwide it also names display diagonals, wheel rims, tire codes and pipe sizes.

1 inch = 0.0254 meters (exactly).

Sources: Wikipedia: Inch; Wikipedia: Yard; NIST Guide to the SI, Appendix B.8: conversion factors

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