Length Converter
Convert between metres, kilometres, feet, inches, miles, yards, and more length units instantly.
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How to use this calculator
- 1
Type the number you want to convert in the "From" field.
- 2
Select the unit you are converting from using the dropdown below the first field.
- 3
Select the unit you want to convert to using the second dropdown.
- 4
The result updates instantly. Use the swap button (⇄) to reverse the conversion.
Frequently asked questions
Is a mile always 1,609.344 metres?
The statute mile used in the US and UK is exactly 1,609.344 m, or 5,280 ft. The nautical mile is a different unit, exactly 1,852 m, so 1 nmi equals 1.150779448 statute miles in this tool. Both are in the list, so pick the one your chart, road sign or flight plan actually uses.
How is the foot defined, and what about the US survey foot?
Since the 1959 international agreement the foot is exactly 0.3048 m and the inch exactly 25.4 mm. The older US survey foot (1200/3937 m) is about two parts per million longer and has been deprecated in the US. This converter uses the international foot only, which only matters for very large survey coordinates.
How many inches are in a metre?
A metre is 39.37007874 inches, because one inch is exactly 0.0254 m. Going the other way, 1 in is 2.54 cm. Those two figures cover most everyday work: multiply inches by 2.54 for centimetres, or divide centimetres by 2.54 for inches.
What does the light year entry measure?
A light year is a distance, not a time: how far light travels in a Julian year of 365.25 days, exactly 9,460,730,472,580,800 m. That is about 9.46 trillion km. The converter uses the full exact figure, so results in km or miles stay accurate even though they are displayed in scientific notation.
Why do some answers show e+12 or e-9?
Results of 1e12 or more, or below 1e-9, are shown in scientific notation, so 1 light year in miles reads 5.878625e+12. Everything between those limits is shown with up to ten significant digits. The underlying calculation is the same either way.
Can I enter feet and inches together, like 5 ft 9 in?
No, the field takes one number in one unit. Change 5 ft 9 in to 69 in (5 × 12 + 9) or to 5.75 ft and convert that. The inches-to-feet page is built around that feet-and-inches split.
What is a micron compared with a micrometre?
Micron is the older name for the micrometre (µm), one millionth of a metre. The list shows it as micrometre; 1 µm is 0.000039370079 in. A nanometre is a thousand times smaller, 1e-9 m.
Length units: metres, miles, feet, inches and nautical miles
Exact definitions behind every factor
Every common length unit is tied to the metre by a fixed figure. The inch is 25.4 mm, the foot is 0.3048 m, the yard is 0.9144 m and the statute mile is 1,609.344 m, all set by the 1959 international yard and pound agreement. The nautical mile is 1,852 m by definition, and the light year is 9,460,730,472,580,800 m, the distance light covers in a Julian year. The converter multiplies by these exact values, so a mile comes out as precisely 5,280 feet and 63,360 inches. Those relationships make mental checks simple: 1 km is 0.62137119 mi, and 1 in is exactly 2.54 cm. The metre itself is defined from the speed of light, so none of these numbers can drift over time.
Reference values taken from the converter
Each row starts from one unit and shows the same distance in four others. Figures are copied from the tool’s output, which keeps up to ten significant digits.
| From | Metres | Feet | Inches | Miles |
|---|---|---|---|---|
| 1 km | 1,000 | 3,280.839895 | 39,370.07874 | 0.62137119 |
| 1 mi | 1,609.344 | 5,280 | 63,360 | 1 |
| 1 nmi | 1,852 | 6,076.115486 | 72,913.385827 | 1.150779448 |
| 1 yd | 0.9144 | 3 | 36 | 0.00056818182 |
| 1 ft | 0.3048 | 1 | 12 | 0.00018939394 |
Worked examples: a sprint and a marathon
A 100 m sprint is 328.0839895 ft, or 3,937.007874 in, which is only 0.062137119 mi. The commonly quoted marathon distance of 42.195 km works out to 26.21875746 mi. A summit listed at 8,848 m is 29,028.871391 ft high. When a figure is quoted in nautical miles, remember the gap: 100 nmi is not 100 mi, since each nautical mile is about 15 percent longer than a statute mile. Keep the context in mind when you round: for a running route, two decimals of a mile is ample, while for a machined part you would want the full metric figure.
Very large and very small lengths
One light year is 9.460730e+12 km, or 5.878625e+12 mi, numbers that only make sense in scientific notation. At the other end, a micrometre is 0.000039370079 in and a nanometre is a billionth of a metre. The list spans from nanometres to light years, so it can help with anything from semiconductor feature sizes to astronomy figures, provided you read the exponent.
Limits worth knowing
The tool takes a single value in a single unit and returns a single value. It does not combine feet and inches in one field, and it does not use the US survey foot. Display precision is about ten significant digits, far finer than any tape measure, so round to the accuracy of your source before copying a result into a drawing or order.
Learn more from an authoritative source:
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Results are estimates for informational purposes only and do not constitute professional financial, medical, legal, or technical advice. Read full disclaimer →