# Length Converter URL: https://speedycalculator.com/calculators/conversion/length-converter/ Last updated: 2026-10-25 > The length converter converts length between millimetres, centimetres, kilometres, inches, feet, yards and more. Choose any “from” and “to” unit, type a number into any field and every other unit updates instantly; all conversion factors are exact definitions. ## Inputs - From (m, km, cm, mm, dm, µm, nm, Å, in, ft, yd, mi, nmi, mil, furlong, chain, rod, fathom, hand, league, AU, ly, pc, R☉, px (96 dpi), pt, gaj) ## Results - To - Centimetres - Kilometres - Inches - Feet - Yards - Miles ## Formula ``` 1 m = 1,000 mm 1 m = 100 cm 1 m = 0.001 km 1 m = 39.370079 in 1 m = 3.2808399 ft ``` ## Explanation Length is the most converted quantity in daily life: a room plan in feet, a fabric length in metres, a running route in miles. Since 1959 the inch has been exactly 2.54 cm and the yard exactly 0.9144 m, so every conversion between metric and imperial lengths here is exact. ### How to use the Length Converter - Pick the unit you are starting from in the **From** menu and type your value. - Pick the unit you want in the **To** menu. The heading changes to match – for example “Meters to Millimeters Converter”. - The most common length units are shown below at the same time, so you can compare them at a glance. - Type into any result to convert backwards, then use **Copy results** – the copied text starts with the heading for your chosen units. Results update as you type. Everything is calculated in your browser. ### How it works Every length unit is defined by an exact factor relative to the metre (the base unit). The calculator first turns the value you type into metres, then turns that into the unit you picked in the “To” menu and into each of the common units below it. This two-step method means any unit can be converted to any other – 27 units are available in each menu – and you can type into any field, including a result, to work in the other direction. Changing a unit menu keeps the quantity the same and just re-expresses it, and the page heading and copied results follow your choice. ### How to convert length units - Choose the unit you have in the **From** menu and type the value, for example **1 m**. - Choose the unit you want in the **To** menu, for example millimetres. The page heading changes to “Meters to Millimeters Converter”. - The calculator multiplies by the metre factor of the “from” unit and divides by the factor of the “to” unit: 1 m × 1 ÷ 0.001 = **1,000 mm**. ### 1 metre in common units UnitValueMillimetres (mm)1,000Centimetres (cm)100Kilometres (km)0.001Inches (in)39.370079Feet (ft)3.2808399Yards (yd)1.0936133Miles (mi)0.00062137119Nautical miles (nmi)0.0005399568 ### Metres conversion table Metresmmcmkmin0.011011 × 10-50.393700790.1100100.00013.93700790.5500500.000519.68503911,0001000.00139.3700791.51,5001500.001559.05511822,0002000.00278.74015755,0005000.005196.850391010,0001,0000.01393.70079100100,00010,0000.13,937.00791,0001,000,000100,000139,370.079 ### What is a metre? The metre is the SI base unit of length. Since 1983 it has been defined as the distance light travels in a vacuum in 1/299,792,458 of a second, which ties it to a fundamental constant rather than a physical bar of metal. ### What is a millimetre? A millimetre is one thousandth of a metre. Engineering drawings, construction plans, rainfall, screws, bolts and jewellery are all dimensioned in millimetres. ### What is a centimetre? A centimetre is one hundredth of a metre (10 mm). It is the everyday metric unit for body height, clothing, furniture and school rulers. ### Common mistakes to avoid Mixing the international foot (0.3048 m) with the old u.s. survey foot, confusing nautical and statute miles, and writing decimal feet such as 5.5 ft as “5 ft 5 in” (it is 5 ft 6 in). ## Worked example Inputs — From: 1 m. Results — **To = 1,000 mm**; Centimetres = 100 cm; Kilometres = 0.001 km; Inches = 39.37007874 in; Feet = 3.2808399 ft; Yards = 1.0936133 yd; Miles = 0.00062137 mi. ## Key terms - **International yard and pound agreement**: 1959 treaty fixing the yard at 0.9144 m and the pound at 0.45359237 kg. - **Nautical mile**: 1,852 m, originally one minute of latitude. ## FAQ **Is a US mile the same as a UK mile?** Yes. Both use the international mile of exactly 1,609.344 m. **What is the survey foot?** An older U.S. foot of 1200/3937 m, retired at the end of 2022; this converter uses the international foot of 0.3048 m. **What is a nautical mile?** 1,852 m exactly, used at sea and in aviation. **How do I change the units?** Pick any unit in the From and To menus. The value is converted in place, and the heading changes to show your conversion, for example “Meters to Millimeters Converter”. **Can I type into any field?** Yes. Every field is editable, so you can start from whichever unit you have. **How many units can I convert between?** 27 length units, from the everyday to the specialised. **Which units are exact?** All factors here are exact by definition except astronomical and similar reference values, which use internationally agreed constants. **What formula does the Length Converter use?** 1 m = 1,000 mm. ## Sources - [NIST Special Publication 811 – Guide for the Use of the International System of Units](https://www.nist.gov/pml/special-publication-811) - [NIST Handbook 44 Appendix C – General tables of units of measurement](https://www.nist.gov/pml/owm/nist-handbook-44-current-edition)