Length Converter
Converts lengths exactly between metric, imperial and nautical units — with the international foot and the legacy US survey foot kept separate.
Convert length
Exact definitions (NIST SP 811) · rounded at display only
1 m =
3.280839895ft
rounded for displayExact value: 1250/381 ft (does not terminate as a decimal)
How this was converted
- Read as: 1
- The metre is the SI base unit of length.
- 1 ft = 0.3048 m exactly (international foot, 1959).
- result = amount × (m in m) ÷ (ft in m)
- In m (exact): 1
All units
| Unit | Value | Actions |
|---|---|---|
| Millimetres (mm) | 1,000 mm | |
| Centimetres (cm) | 100 cm | |
| Metres (m) | 1 m | |
| Kilometres (km) | 0.001 km | |
| Inches (in) | 39.37007874 in≈ | |
| Feet (ft, international) | 3.280839895 ft≈ | |
| Yards (yd) | 1.093613298 yd≈ | |
| Miles (mi, international) | 0.0006213711922 mi≈ | |
| Nautical miles (nmi) | 0.0005399568035 nmi≈ | |
| US survey feet (legacy) | 3.280833333 US survey ft≈ |
≈ marks a value rounded for display. ☆ pins a unit to the top for this visit (nothing is stored).
Exact unit definitions
| Unit | 1 unit in m (exact) |
|---|---|
| Millimetres (mm) | 1 mm = 0.001 m exactly (SI prefix). |
| Centimetres (cm) | 1 cm = 0.01 m exactly (SI prefix). |
| Metres (m) | The metre is the SI base unit of length. |
| Kilometres (km) | 1 km = 1000 m exactly (SI prefix). |
| Inches (in) | 1 in = 0.0254 m = 25.4 mm exactly (international inch, 1959). |
| Feet (ft, international) | 1 ft = 0.3048 m exactly (international foot, 1959). |
| Yards (yd) | 1 yd = 0.9144 m exactly (international yard, 1959). |
| Miles (mi, international) | 1 mi = 1609.344 m exactly (international mile = 5280 ft). |
| Nautical miles (nmi) | 1 nmi = 1852 m exactly (international nautical mile). |
| US survey feet (legacy) | 1 US survey foot = 1200/3937 m exactly (≈ 0.3048006096 m). Legacy unit, deprecated by NIST from 1 January 2023 — kept for old US survey records only. It is NOT the international foot. |
How to use this calculator
- Type the amount: a signed decimal (-2.5), scientific notation (1e6) or an explicit fraction such as 5 3/8.
- Choose the unit you have (From) and the unit you want (To). Swap reverses them and keeps exactly what you typed.
- Read the answer and its exact or rounded label, then use the all-units table to find, pin or copy any unit.
How it works
Every conversion goes through metres using exact definitions: 1 in = 0.0254 m, 1 ft = 0.3048 m, 1 yd = 0.9144 m, 1 mi = 1609.344 m and 1 nautical mile = 1852 m (international units, NIST SP 811).
result = amount × (from-unit in m) ÷ (to-unit in m). The arithmetic uses exact fractions, so nothing is lost; only the displayed digits are rounded, and a rounded value is marked with its exact value shown.
The legacy US survey foot (exactly 1200/3937 m ≈ 0.3048006 m) is a separate, labelled unit and is never used for “ft”. Blank boxes, text, commas and Infinity are rejected rather than treated as zero.
Worked example
1 metre in feet, millimetres and centimetres. 1 m ÷ 0.3048 m/ft = 1250/381 ft = 3.280839895 ft (rounded to 10 significant figures; the exact value is 1250/381 ft). The same 1 m is exactly 1,000 mm and 100 cm, and 1 in is exactly 25.4 mm.
Frequently asked questions
Which foot definition does this use?
“Feet (ft)” is the international foot, exactly 0.3048 m. The US survey foot (exactly 1200/3937 m, about 2 parts per million longer) is listed separately as a legacy unit for older US survey records; the two are never mixed.
Are the conversions exact?
The unit definitions are exact and the arithmetic uses exact fractions, so 1 in = 25.4 mm exactly. Results that do not end as a short decimal, such as 1 m = 3.280839895… ft, are rounded only for display and marked as rounded, with the exact value shown.
Can I enter fractions?
Yes, as explicit fractions: 3/8, 5 3/8 or 5-3/8 (the whole number and the fraction are in the same unit). Decimals and scientific notation such as 1e6 work too; commas are not accepted because they are ambiguous.
Does it work offline and stay private?
Yes — the conversion runs entirely in your browser, with no sign-up and nothing sent to a server.
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Cite this tool
Zerdly. (2026). Length Converter. Retrieved from https://www.zerdly.com/tools/length-converter/
Tip: Enter any known values to calculate the remaining results.
Designed to run locally in your browser. Tool inputs are not intentionally stored by Zerdly unless stated otherwise.