Length Converter

How the converter works

Every unit is stored as an exact number of metres. To convert, the value is multiplied by the source unit's size in metres and divided by the target unit's size. Converting 5 feet to metres is therefore 5 × 0.3048 ÷ 1 = 1.524 m, and converting 1.524 m back to feet reverses it exactly.

result = value × (metres per source unit) ÷ (metres per target unit)

The inch, foot, yard and mile were fixed to these metric values by the 1959 international yard and pound agreement. The nautical mile was set at exactly 1,852 metres by international agreement in 1929 and is based on one minute of latitude.

Worked examples

Example 1: a room 12 feet long

12 × 0.3048 = 3.6576 m. For floor plans you would round to 3.66 m.

Example 2: a 10 km race in miles

10,000 m ÷ 1,609.344 = 6.213712 mi, usually quoted as 6.2 miles.

Example 3: 750 mm in feet and inches

750 mm ÷ 25.4 = 29.527559 in. That is 2 ft (24 in) plus 5.53 in, or about 2 ft 5½ in.

Example 4: 3 nautical miles in kilometres

3 × 1,852 m = 5,556 m = 5.556 km, the width of an old "three-mile" territorial limit expressed in metric.

How to read the result

The headline is your value in the target unit. The formula line shows the single multiplier that links the two units for this conversion, such as 0.3048 from feet to metres, so you can reuse it in a spreadsheet. The table below lists the same length in every unit, with the target highlighted. Results show up to six decimal places with trailing zeros removed; a computer stores values in binary, so the converter trims the last few digits of floating-point noise that would otherwise turn 2.54 into 2.5399999999999996.

Metric and imperial at a glance

The metric system scales by powers of ten: 10 mm in a centimetre, 100 cm in a metre, 1,000 m in a kilometre. That makes conversions inside the system a matter of moving the decimal point. The imperial and US customary units grew from older traditions and use mixed ratios: 12 inches in a foot, 3 feet in a yard, 1,760 yards in a mile, so 5,280 feet in a mile. The US uses customary units for most everyday lengths, while the UK uses miles on road signs, feet and inches for personal height, and metric for most else. Science, medicine and almost every other country use metric throughout.

Common uses

Typical jobs include converting room and furniture dimensions when shopping across borders, turning race distances between kilometres and miles, reading screen and wheel sizes quoted in inches, checking product dimensions on import listings, and converting altitude or depth between feet and metres for hiking, flying or diving. Sailors and pilots use nautical miles for distance because one nautical mile corresponds to one minute of arc along a meridian, which makes chart work simple. For quick heights and body measurements, the dedicated cm to inches converter also gives a feet-and-inches breakdown.

Limits and good practice

The US survey foot, used historically for some land surveying in the United States, is very slightly longer (1200/3937 m) than the international foot used here; it was officially retired at the end of 2022 but still appears in older property records. Over short distances the difference is negligible, but over hundreds of kilometres it adds up to metres. Also match the precision of the answer to the precision of the measurement: a tape-measured 12 ft does not become precise to the micrometre by converting it. To convert weights or temperatures, use the weight converter or the temperature converter.

Converting compound measurements

Imperial lengths are often written in two units at once, such as 5 ft 9 in or 2 mi 300 yd. Convert each part and add them, or first turn everything into the smaller unit: 5 ft 9 in is 69 in, and 69 × 2.54 = 175.26 cm. Going the other way, convert to the smaller unit, then divide by the ratio and keep the remainder: 2.5 m is 98.425 in, which is 8 ft 2.4 in. Metric lengths never need this, because they are written as a single decimal number, which is one reason science and engineering adopted them. When in doubt, enter the value in the smaller unit to avoid mixing.