Because the inch was defined as exactly 2.54 cm in 1959, and twelve of those make 30.48 cm. Nothing was measured; it was agreed.

Converters Length

Feet to metres

Feet

Metres 1.8288

Decimals

Live · 1 ft = 0.3048 m exactly

From a doorway to cruising altitude

1 ft 0.3048 m

5 ft 1.524 m

6 ft 1.8288 m

10 ft 3.048 m

100 ft 30.48 m

1,000 ft 304.8 m

35,000 ft 10,668 m

One foot is exactly 0.3048 metres, so multiply feet by 0.3048. Six feet is 1.8288 m, a ten-foot ceiling is 3.048 m, and a cruising altitude of 35,000 feet is 10,668 m. The factor follows from the inch being defined as 2.54 cm and there being twelve inches to the foot.

How to convert feet to metres

1 Enter the measurement in feet. For five feet nine, type 5.75.

2 Read the result in metres.

3 Press ⇄ to convert metres back to feet.

Feet and inches together need one extra step: divide the inches by twelve and add them on. Five feet nine inches is 5 + 9/12 = 5.75 feet, which is 1.7526 m. Aviation is the one field that stayed on feet worldwide for altitude while using metric for almost everything else, which is why flight levels are quoted in hundreds of feet.

Questions

How do I convert five foot nine? −

Nine inches is 0.75 of a foot, so enter 5.75. The answer is 1.7526 metres, or 175.26 cm.

Why is 0.3048 exact? +

What was the US survey foot? +

Why do aircraft still use feet? +

Sources

NIST — deprecation of the US survey foot NIST Special Publication 811 — guide for the use of the SI

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