Unit Converter
Convert length, weight, temperature, volume, area, speed, data, energy and more, with every unit at once.
0.3937007874 in
Formula: in = cm ÷ 2.54
In every unit of length
| Unit | Value | Copy |
|---|---|---|
| Nanometre | 10,000,000 nm | |
| Micrometre | 10,000 µm | |
| Millimetre | 10 mm | |
| Centimetre | 1 cm | |
| Metre | 0.01 m | |
| Kilometre | 0.00001 km | |
| Thou (mil) | 393.7007874 mil | |
| Inch | 0.3937007874 in | |
| Foot | 0.03280839895 ft | |
| Yard | 0.01093613298 yd | |
| Mile | 0.000006213711922 mi | |
| Nautical mile | 0.000005399568035 nmi |
Converts a value between 144 units across 14 quantities, from millimetres and pounds to kilowatt-hours and litres per 100 km. Alongside the result it shows the formula it used and the same value in every other unit of the quantity, so one entry answers every pair.
How to use it
Choose a quantity, type a value, and pick the units to convert from and to. The unit pickers search names, symbols and everyday spellings — lbs, sq ft, celsius, Mbps — and list the common units first. The swap button reverses the pair.
Values may be grouped the international way (1,234,567) or the Indian way (12,34,567), and written with an exponent (1e6). A comma is always digit grouping, never a decimal point. Only temperature and angle accept negative values.
- Precision — Auto shows up to 10 significant figures, and every whole-number digit, with trailing zeros trimmed; Fixed shows 0 to 10 decimal places. It applies to the result and to every row of the table. A value too small for the chosen places is shown in scientific notation instead of as zero.
- Group digits — separates thousands with commas; on by default.
Under Auto, values of 10¹⁵ and above, or below 10⁻⁶, are written in scientific notation, such as 1.23 × 10⁻⁷. The copy buttons copy that as 1.23e-7, which spreadsheets and calculators read. The address bar keeps the quantity, value and units, so a copied link opens the same conversion. Everything runs in your browser.
How the conversions work
Each unit is stored as an exact factor to a base unit of its quantity, written as a decimal: the inch is 0.0254 m and the pound 0.45359237 kg by definition. The factor between two units is worked out exactly from those decimals before any arithmetic, so 1 inch shows as 2.54 cm, never 2.5399999999999996.
The formula multiplies by the factor when it is a short exact decimal, or divides by its inverse when that one is. Otherwise it shows the factor rounded to 10 significant figures, marked with ≈. The same mark appears whenever a unit has no exact definition: the radian, the average month and year, and the US therm.
Temperature scales have different zero points, so they convert with an offset as well as a factor. Fuel consumption in litres per 100 km is the reciprocal of fuel economy, so 0 km/L has no equivalent in it. A month is 30.436875 days and a year 365.2425 days, the averages of the Gregorian calendar.
cm = in × 2.54
in = cm ÷ 2.54
°F = °C × 9/5 + 32
°C = (°F − 32) × 5/9
L/100 km ≈ 235.2145833 ÷ US mpg
Examples
A height in feet
6 ft is 1.8288 m. Formula: m = ft × 0.3048.
Body temperature
98.6 °F is 37 °C. Formula: °C = (°F − 32) × 5/9.
A car's fuel economy
40 UK mpg is 7.062023408 L/100 km. Formula: L/100 km ≈ 282.4809363 ÷ UK mpg.
Higher is better in miles per gallon and lower is better in litres per 100 km, since one is the inverse of the other.
Broadband speed
100 Mbit/s is 12.5 MB/s. Formula: MB/s = Mbit/s × 0.125.
Connections are sold in bits per second and downloads are shown in bytes, eight bits each.
What it converts
| Quantity | Units |
|---|---|
| Length | nm, µm, mm, cm, m, km, mil, in, ft, yd, mi, nmi |
| Weight (mass) | µg, mg, g, kg, t, gr, ct, oz, oz t, lb, st, st + lb, US ton, UK ton, tola |
| Temperature | °C, °F, K, °R |
| Volume | mL, L, m³, cm³, in³, ft³, US tsp, US tbsp, US fl oz, US cup, legal cup, US pt, US qt, US gal, imp fl oz, imp pt, imp qt, imp gal, metric tsp, metric tbsp, metric cup, AU tbsp, bbl |
| Area | mm², cm², m², ha, km², in², ft², yd², ac, mi² |
| Speed | m/s, km/h, mph, kn, ft/s |
| Time | ns, µs, ms, s, min, h, d, wk, mo, yr |
| Data storage | bit, kbit, Mbit, Gbit, B, kB, MB, GB, TB, PB, KiB, MiB, GiB, TiB, PiB |
| Data rate | bit/s, kbit/s, Mbit/s, Gbit/s, B/s, kB/s, MB/s, GB/s, KiB/s, MiB/s |
| Pressure | Pa, kPa, MPa, bar, mbar, psi, atm, mmHg, Torr, inHg, kgf/cm² |
| Energy | J, kJ, MJ, cal, kcal, cal (IT), Wh, kWh, BTU, eV, ft·lbf, thm |
| Power | W, kW, MW, hp, hp (E), PS, BTU/h |
| Fuel economy | km/L, L/100 km, US mpg, UK mpg |
| Angle | °, rad, gon, turn, ′, ″ |
Definitions and sources
The inch (0.0254 m) and the pound (0.45359237 kg) are exact by the 1959 international yard and pound agreement; feet, yards, miles, ounces, stones and tons follow from them. The US gallon is 231 cubic inches (3.785411784 L) and the imperial gallon 4.54609 L. Factors follow NIST Special Publication 811, Appendix B, and NIST Handbook 44, Appendix C.
The US survey foot, which differs from the international foot by two parts in a million, has been deprecated since 1 January 2023 and is not offered.
Decimal prefixes count in thousands (1 kB = 1000 bytes) and binary prefixes in powers of two (1 KiB = 1024 bytes), as the IEC standardised. The US legal cup of 240 mL is the one used on nutrition labels; the customary cup is 236.5882365 mL. The electronvolt is exact since the 2019 redefinition of the SI.
Sources
- Guide for the Use of the International System of Units (SP 811), Appendix B — NIST
- Handbook 44, Appendix C: General Tables of Units of Measurement — NIST
- U.S. Survey Foot — NIST
- Definitions of the SI units: the binary prefixes — NIST
- 21 CFR 101.9(b)(5)(viii), nutrition labeling household measures — Legal Information Institute
Reviewed
Frequently asked questions
See also
- Length Converter — with centimetre-to-inch and metre-to-foot tables.
- Weight Converter — with stone and pounds, and a kilogram-to-pound table.
- Temperature Converter — with a table of everyday temperatures.
- Height Converter — for centimetres to feet and inches, and back.
- Area Converter — with square-metre-to-square-foot and acre-to-hectare tables.
- Volume Converter — with a table of kitchen measures.
- Data Storage Converter — with drive sizes in binary units.
- Land Area Converter — for bigha, guntha, rai, pyeong and other land units.
- Gold Weight Converter — for tola, tael, baht and sovereign, with fine gold content.