Feet to Centimeters Converter

feet to centimeters — quick reference

The formula, worked line by line

One multiplication by an exact constant. The foot is exactly 0.3048 metres, so 30.48 centimetres is a definition rather than a measured factor, and there is no more precise version of it anywhere.

The reason to prefer that route is not arithmetic but safety. Multiplying feet by 30.48 requires the feet value to be a true decimal, and a height rarely is. Converting to inches first removes the only place the conversion can go wrong.

centimetres = feet x 30.48
6 x 30.48 = 182.88 cm
or: total inches x 2.54
5 ft 9 in = 69 in, 69 x 2.54 = 175.26 cm
using 30 instead of 30.48 is 1.6 percent low

Rounding once, at the end

Convert, then round. Rounding the feet figure first and converting afterwards compounds the error, and rounding at every intermediate step compounds it further. This matters most on multi-step conversions, where three roundings can move an answer further than any of them individually suggests.

Where each unit is actually recorded

How to use the feet to centimeters converter

A foot is exactly 30.48 centimetres. Not about, not approximately — exactly, because the 1959 international agreement fixed the yard at 0.9144 metres and the foot is a third of that. Multiplying by 30.48 is therefore an exact operation, and any imprecision in the answer came in with the measurement rather than the conversion.

The number people actually use in their heads is 30, and it is worth knowing what that costs. Thirty is 1.6 percent short of 30.48. On a six-foot height that is 2.9 centimetres, which is more than an inch. Across a hundred feet it is nearly half a metre. The shortcut is fine for a rough sense of scale and wrong for anything recorded.

For heights there is a shorter route. Convert the whole thing to inches first, then multiply by 2.54. Five foot nine is sixty-nine inches, and sixty-nine times 2.54 is exactly 175.26 centimetres. One multiplication instead of two, and no decimal fraction of a foot to get wrong on the way.

That asymmetry explains a lot of apparent disagreement between sources. A height recorded in centimetres and displayed in feet and inches has been rounded; a height recorded in inches and displayed in centimetres has not. Converting back and forth a few times will drift, and the drift is entirely in the rounding rather than the factor.

What the rounded thirty actually costs

Mental arithmetic needs a round number and thirty is the obvious candidate. It is also 1.6 percent low, and percentage errors are deceptive because they scale with whatever you apply them to. On a doorway it is invisible. On a building it is a real discrepancy that someone has to reconcile.

The same warning applies to the other familiar approximations. A metre is not exactly three feet and three inches, a kilometre is not exactly 0.6 miles, and a mile is not exactly 1.6 kilometres — it is 1.609344. Each is a useful mental shortcut and none belongs in a document.

Why the factor is exact at all

Before 1959 the inch differed slightly between countries, and calibration laboratories in the English-speaking world were working to marginally different standards. The international yard and pound agreement fixed the yard at exactly 0.9144 metres and the pound at exactly 0.45359237 kilograms, taking effect in the United States on 1 July 1959.

One legacy complication has now closed. The United States kept a separate survey foot, very slightly longer, for geodetic work. It was deprecated at the end of 2022, so for anything measured since 1 January 2023 there is a single foot of exactly 0.3048 metres, and survey-foot values are a legacy-data concern only.

Every feet value, worked out

30 common feet figures each get their own page, with the answer at full precision, the arithmetic, what rounding costs, and the nearest real-world reference point on the scale.

Questions people ask