Unit Converter
Length, weight, volume, area, speed, temperature, data and more.
Last updated
Your details
Result
- 1.000000 m =
- 3.280840 ft
- Reverse
- 1 ft = 0.304800 m
How the conversions work
Every linear category defines each unit as a multiple of one base unit — metres for length, kilograms for weight, seconds for time. Converting is then a single multiply and divide, which avoids the rounding drift that comes from chaining conversions.
Temperature is the exception. Celsius, Fahrenheit and Kelvin have different zero points as well as different scales, so they need an offset rather than a simple factor. Converting 0°C to Fahrenheit gives 32, not 0.
Data sizes come in two families
The decimal units follow the same pattern as everything else here: a kilobyte is 1,000 bytes and a gigabyte is 1,000,000,000, exactly as the SI defines them and as storage and network equipment is sold.
The binary units are listed separately — a kibibyte is 1,024 bytes and a gibibyte is 1,073,741,824. Operating systems count this way but often still write "GB", which is why a "1 TB" drive shows as roughly 931 GB once formatted. No capacity is missing; one side is using the other side's names.
Formula & methodology
What this calculator assumes
- Conversion factors are the exact defined values where one exists — the inch is exactly 2.54 cm and the pound exactly 0.45359237 kg by the 1959 international agreement.
- Temperature is handled separately, because the scales have different zero points and need an offset rather than a factor.
- The year is the Julian year of 365.25 days, the astronomical convention, which is also what makes the light-year exact.
Sources
- Bureau International des Poids et Mesures, The International System of Units (SI), 9th edition, 2019.
- NIST Special Publication 811, Guide for the Use of the International System of Units, 2008 — conversion factors for customary units.
Frequently asked questions
Why do some results show many decimal places?
Most conversion factors are irrational or non-terminating in decimal. Six places is shown to keep small values meaningful; round to whatever precision your task actually needs.
Should I use this or a dedicated conversion page?
Use this when you are moving between many units in one sitting, and a dedicated page when you want a single pair explained — those carry the exact factor, the formula in both directions, a worked example and a reference table you can scan.
Why can I not convert between categories?
Because there is no factor between a kilogram and a litre. Converting mass to volume requires the density of the specific substance, which is a property of the material rather than of the units, so it belongs in a tool that asks what the material is.
Are the conversion factors exact?
Where an exact legal definition exists, yes — an inch is exactly 25.4 mm and a pound is exactly 0.45359237 kg. Everything is carried at full double precision internally and rounded only for display, so results are never calculations performed on already-rounded numbers.
All length units
| Unit | Value |
|---|---|
| Millimeter | 1,000.000000 mm |
| Centimeter | 100.000000 cm |
| Kilometer | 0.001000 km |
| Inch | 39.370079 in |
| Foot | 3.280840 ft |
| Yard | 1.093613 yd |
| Mile | 0.000621 mi |
| Nautical Mile | 0.000540 nmi |