Length Converter

How to use

1. 1Type a value into the input. You can paste a number with a comma decimal, a thousand separator, or an optional unit suffix like 30 cm, 5 ft, or 10 km.
2. 2Pick the source unit from the Metric, Imperial, or Specialty groups. The result columns update with every other unit at once.
3. 3Use Show units to focus on Metric only, Imperial only, or all units, and Decimal places to round results between 0 and 6 places.
4. 4Read the Human readable card to see the cleanest representation in each system, plus a dedicated Feet and inches row in the 5 ft 11 in format used for human heights.
5. 5Tap a common reference point (pencil, paper size, basketball court, marathon, Eiffel Tower) to load that length, or click Copy on any result card to grab the converted value.

About this tool

Length Converter turns any length value into every common unit at the same time, so you can read metric and imperial results side by side instead of opening a calculator and a search tab. Type a number, pick a source unit (millimeter, centimeter, meter, kilometer, inch, foot, yard, mile, or nautical mile), and the result cards update instantly with the converted value, the meter equivalent, and a copy button on every result. Conversions go through a single canonical meters value internally, with unit factors locked to the international yard definition (1 yd = 0.9144 m exactly, 1 in = 25.4 mm exactly), the SI definition of the meter, and the international nautical mile (1 NM = 1852 m exactly), so results stay consistent and round-trip correctly: 1 mile is 1.609344 km, 1 inch is 2.54 cm, 1 m is 39.37 inches. Inputs accept comma decimal separators, thousand separators, scientific notation, and an optional unit suffix (cm, ft, in, mi, NM, etc), so values pasted from a script, a product spec, or a survey just work. When the suffix you typed does not match the selected source unit, a one-click swap switches the source so you do not silently get the wrong reading. The tool also surfaces a human readable summary that picks the largest unit where the value is at least 1 in each system, plus a dedicated feet and inches row in the format 5 ft 11 in for the height-conversion intent that browsers see most often. The decimal places control rounds results to 0, 2, 4, or 6 places depending on whether you want a clean headline number or a precise engineering reading. A reference panel ships real-world sizes (a pencil, A4 and US Letter paper, an arm span, an interior door, a sedan, a tennis court, a basketball court, an Olympic pool, a football field, the Eiffel Tower, a mile, a 5K, a marathon, Mount Everest) that tap to load instantly. Useful for converting heights between feet and centimeters, sanity-checking product specs that quote one system in a country that uses the other, planning a run or a hike, comparing screen and table dimensions, sizing furniture against doorways, and any moment you need to translate a length without trusting a fragile mental shortcut. Everything runs locally on your device, so the values you type here are never uploaded.

Free to use. Works in your browser. No signup, no login.