Conversion Calculator
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Results
1 ft = 0.3048 m
| ft | m |
|---|---|
| 1 | 0.3048 |
| 2 | 0.6096 |
| 5 | 1.524 |
| 10 | 3.048 |
| 20 | 6.096 |
| 50 | 15.24 |
| 100 | 30.48 |
| 1,000 | 304.8 |
How to use the conversion calculator
- Choose the quantity: length, area, volume, weight, temperature, speed, time, pressure, energy, power, data storage, fuel economy or angle.
- Enter the value and pick the units to convert from and to. Swap units reverses the direction.
- Read the result, the conversion factor or formula, and a table of common values for the same pair of units.
Conversion formulas
temperature: °F = °C × 9/5 + 32 K = °C + 273.15
fuel economy: L/100 km = 235.214583 ÷ mpg (US)
Each unit is stored as its size in the SI unit for its quantity: meters for length, kilograms for mass, joules for energy and so on. Converting means going to the SI unit and back out, so 1 ft = 0.3048 m and 1 in = 0.0254 m give 1 ft ÷ 1 in = 12. Two kinds of quantity need more than a factor. Temperature scales have different zero points, so they need an offset as well. Fuel economy in liters per 100 km measures fuel per distance while miles per gallon measures distance per fuel, so one is the reciprocal of the other: doubling mpg halves L/100 km.
Worked example
A room at 72 °F is (72 − 32) × 5/9 = 22.22 °C. Five miles is 5 × 1.609344 = 8.04672 km, exactly, because the mile is defined as 1,609.344 m. A car that does 30 mpg (US) uses 7.84 L/100 km, the same as 36.03 mpg in UK gallons.
Exact definitions used
| Quantity | Unit | Definition |
|---|---|---|
| Length | inches (in) | 1 inch = 2.54 cm exactly |
| Length | feet (ft) | 1 foot = 12 in = 0.3048 m exactly |
| Length | miles (mi) | 1 mile = 5,280 ft = 1,609.344 m exactly |
| Area | acres (ac) | 1 acre = 43,560 ft² = 4,046.8564224 m² |
| Volume | US gallons (US gal) | 1 US gallon = 231 in³ = 3.785411784 L exactly |
| Volume | UK gallons (UK gal) | 1 UK gallon = 4.54609 L exactly |
| Weight and mass | pounds (lb) | 1 pound = 0.45359237 kg exactly |
| Weight and mass | ounces (oz) | 1 ounce = 1/16 pound |
| Pressure | standard atmospheres (atm) | 1 atm = 101,325 Pa exactly |
| Energy | British thermal units (BTU) | 1 BTU (International Table) = 1,055.05585262 J |
| Energy | kilowatt-hours (kWh) | 1 kWh = 3.6 MJ exactly |
| Power | horsepower (mechanical) (hp) | 1 hp = 550 ft·lbf/s ≈ 745.7 W |
Common conversions
| Unit | Equals | Unit | Equals |
|---|---|---|---|
| 1 inch | 2.54 cm | 1 US gallon | 3.78541 L |
| 1 foot | 0.3048 m | 1 UK gallon | 4.54609 L |
| 1 mile | 1.60934 km | 1 liter | 33.814 US fl oz |
| 1 meter | 3.28084 ft | 1 acre | 4,046.86 m² |
| 1 pound | 0.453592 kg | 1 psi | 6.89476 kPa |
| 1 kilogram | 2.20462 lb | 1 horsepower | 0.7457 kW |
Temperature table
| °C | °F | K |
|---|---|---|
| −40 | −40 | 233.15 |
| −18 | −0.4 | 255.15 |
| 0 | 32 | 273.15 |
| 10 | 50 | 283.15 |
| 20 | 68 | 293.15 |
| 25 | 77 | 298.15 |
| 30 | 86 | 303.15 |
| 37 | 98.6 | 310.15 |
| 100 | 212 | 373.15 |
| 180 | 356 | 453.15 |
| 200 | 392 | 473.15 |
| 230 | 446 | 503.15 |
Fuel economy: mpg to L/100 km
| mpg (US) | L/100 km | mpg (UK) |
|---|---|---|
| 15 | 15.68 | 18 |
| 20 | 11.76 | 24 |
| 25 | 9.41 | 30 |
| 30 | 7.84 | 36 |
| 35 | 6.72 | 42 |
| 40 | 5.88 | 48 |
| 50 | 4.7 | 60 |
Why your 1 TB drive shows 931 GB
Storage makers use decimal (SI) prefixes, where 1 GB is 10⁹ bytes, while many operating systems count in binary units of 2³⁰ bytes, properly called gibibytes (GiB) but often labeled "GB". No space is missing; it is the same number of bytes measured two ways.
| Advertised (GB) | Shown as GiB |
|---|---|
| 256 GB | 238.4 GiB |
| 500 GB | 465.7 GiB |
| 1,000 GB | 931.3 GiB |
| 2,000 GB | 1,862.6 GiB |
| 4,000 GB | 3,725.3 GiB |
Tips for accurate conversions
- Check which gallon, pint or ton. US and UK gallons differ by about 20%, and a US (short) ton is 2,000 lb while a UK (long) ton is 2,240 lb and a metric ton is 1,000 kg.
- Round at the end. The calculator keeps full precision and shows up to 10 significant digits; round only the final answer.
- Bits and bytes. Network speeds are in bits per second, file sizes in bytes. The bandwidth calculator handles download times.
The calculator covers 13 categories and 128 units. For building materials, try the square footage calculator; for physics, the speed calculator and density calculator.
Sources
- NIST, Special Publication 811, Guide for the Use of the International System of Units (2008), Appendix B.
- NIST, Handbook 44 (2025), Appendix C, General Tables of Units of Measurement.
- IEC 80000-13, binary prefixes (kibi, mebi, gibi) for data storage.
Frequently asked questions
How many centimeters are in an inch?
Exactly 2.54. Since 1959 the inch has been defined as 0.0254 m, so 1 foot is exactly 30.48 cm and 1 mile is exactly 1,609.344 m. Going the other way, 1 meter is about 3.2808 feet or 39.37 inches.
How do I convert Fahrenheit to Celsius?
Subtract 32, then multiply by 5/9: 72 °F is (72 − 32) × 5/9 ≈ 22.22 °C. To go from Celsius to Fahrenheit, multiply by 9/5 and add 32, so 100 °C is 212 °F. The two scales meet at −40, where −40 °C equals −40 °F.
Is a US gallon the same as a UK gallon?
No. A US gallon is 231 cubic inches, exactly 3.785411784 liters, while a UK (imperial) gallon is exactly 4.54609 liters, about 20% more. That is why 30 miles per US gallon is about 36 miles per UK gallon.
How do I convert mpg to liters per 100 km?
Divide 235.215 by the US mpg figure (or 282.481 by UK mpg). 30 mpg (US) is about 7.84 L/100 km and 50 mpg (US) is about 4.70 L/100 km. Because the units are reciprocals, a higher mpg means a lower L/100 km.
What is the difference between GB and GiB?
A gigabyte (GB) is 1,000,000,000 bytes (SI prefix); a gibibyte (GiB) is 2³⁰ = 1,073,741,824 bytes (IEC binary prefix). A 1 TB drive holds about 931.3 GiB, which some operating systems display as "931 GB" even though nothing is missing.