Unit conversion tables with live converters
Data last checked 2026-09-20
Each section gives the exact conversion factors and a small converter: pick the units, type a value and read the result. Length and mass factors between metric and imperial are exact by international agreement (1959): an inch is exactly 25.4 mm and a pound exactly 0.45359237 kg. Volume factors follow from the cubic inch for US units and from the 4.54609-litre gallon for imperial units.
The data-size section deserves attention because two systems coexist. Storage vendors and the SI use decimal prefixes (1 GB = 1,000,000,000 bytes); operating systems and memory use binary prefixes (1 GiB = 1,073,741,824 bytes), and Windows labels the binary unit "GB", which is why a 1 TB drive shows about 931 GB. Upload limits such as "200 KB" are usually enforced in binary kilobytes (204,800 bytes), but not always; the compressors on this site aim slightly under the target to be safe either way.
Results are shown with up to six significant decimals; the converters use the full-precision factors listed in the tables.
Length
Exact by definition since 1959: 1 inch = 25.4 mm.
8 rows
| From | Equals | Note |
|---|---|---|
| 1 inch | 25.4 mm = 2.54 cm | Exact. |
| 1 foot (12 in) | 0.3048 m = 30.48 cm | Exact. |
| 1 yard (3 ft) | 0.9144 m | Exact. |
| 1 mile (1760 yd) | 1.609344 km | Exact. |
| 1 nautical mile | 1852 m = 1.150779 mi | Exact (international). |
| 1 cm | 0.393701 in | |
| 1 m | 3.280840 ft = 39.37008 in = 1.093613 yd | |
| 1 km | 0.621371 mi |
Mass (weight)
Exact by definition since 1959: 1 pound = 0.45359237 kg.
8 rows
| From | Equals | Note |
|---|---|---|
| 1 pound (16 oz) | 0.45359237 kg = 453.59237 g | Exact. |
| 1 ounce | 28.349523 g | |
| 1 stone (14 lb) | 6.35029318 kg | Exact; UK body weight. |
| 1 troy ounce | 31.1034768 g | Exact; gold and silver prices. |
| 1 kg | 2.204623 lb = 35.27396 oz | |
| 1 tonne (1000 kg) | 2204.623 lb = 1.102311 US short tons | |
| 1 US short ton (2000 lb) | 907.18474 kg | Exact. |
| 1 UK long ton (2240 lb) | 1016.0469 kg |
Volume
US and imperial units differ: a US gallon is about 83% of an imperial gallon.
8 rows
| From | Equals | Note |
|---|---|---|
| 1 US gallon (128 US fl oz) | 3.785411784 l | Exact. |
| 1 imperial gallon (160 imp fl oz) | 4.54609 l | Exact. |
| 1 US fluid ounce | 29.5735 ml | |
| 1 imperial fluid ounce | 28.4131 ml | |
| 1 US cup | 240 ml (FDA legal cup); 236.588 ml (customary) | Recipes usually mean 240 ml. |
| 1 US tablespoon / teaspoon | 14.787 ml / 4.929 ml | Metric recipes use 15 ml / 5 ml. |
| 1 litre | 0.264172 US gal = 0.219969 imp gal = 33.814 US fl oz | |
| 1 cubic metre | 1000 l = 35.3147 cu ft |
Area
Derived from the length factors, so the square units are also exact.
6 rows
| From | Equals | Note |
|---|---|---|
| 1 square foot | 0.09290304 m² | Exact. |
| 1 square metre | 10.76391 sq ft = 1.19599 sq yd | |
| 1 acre (43,560 sq ft) | 4046.8564 m² = 0.404686 ha | |
| 1 hectare (10,000 m²) | 2.471054 acres | |
| 1 square mile (640 acres) | 2.589988 km² | |
| 1 square kilometre | 0.386102 sq mi = 247.105 acres |
Temperature
Formulas: °F = °C × 9/5 + 32; °C = (°F − 32) × 5/9; K = °C + 273.15.
6 rows
| From | Equals | Note |
|---|---|---|
| 0 °C (water freezes) | 32 °F = 273.15 K | |
| 37 °C (body temperature) | 98.6 °F | |
| 100 °C (water boils at sea level) | 212 °F = 373.15 K | |
| −40 °C | −40 °F | The scales cross here. |
| 0 K (absolute zero) | −273.15 °C = −459.67 °F | |
| 45 °C (Gulf summer afternoon) | 113 °F |
Data sizes: decimal (SI) vs binary (IEC)
Drive makers and network speeds use decimal prefixes (1 GB = 10⁹ B); operating systems often show binary sizes (1 GiB = 2³⁰ B), which Windows still labels "GB".
9 rows
| From | Equals | Note |
|---|---|---|
| 1 byte | 8 bits | |
| 1 kB (kilobyte) | 1000 B | SI prefix. |
| 1 KiB (kibibyte) | 1024 B | IEC binary prefix; what Windows calls "KB". |
| 1 MB | 1,000,000 B = 0.953674 MiB | |
| 1 MiB | 1,048,576 B = 1.048576 MB | |
| 1 GB | 10⁹ B = 0.931323 GiB | A "1 TB" drive shows as about 931 GiB in Windows. |
| 1 GiB | 2³⁰ B = 1.073742 GB | |
| 1 Mbit/s | 0.125 MB/s = 125 kB/s | A 100 Mbit/s line downloads at most 12.5 MB/s. |
| "200 KB" upload limit | 204,800 B if binary, 200,000 B if decimal | Portals rarely say which; GivenTool compressors use 1024 and stay a little under the target. |
Sources
Frequently asked questions
Why does my 1 TB drive show 931 GB?
The drive holds 1,000,000,000,000 bytes (decimal terabyte). Windows divides by 1024 three times and calls the result GB, giving 931.3 "GB", which are really GiB. Nothing is missing.
Is a US cup 240 ml or 236.6 ml?
The customary cup is 236.588 ml (half a US pint). US food labelling defines a legal cup of exactly 240 ml, and most modern recipes and measuring cups use 240. The difference is 1.4%.
How do I convert Celsius to Fahrenheit in my head?
Double the Celsius figure and add 30 for a quick estimate (25 °C → 80 °F, true value 77). For exact values multiply by 1.8 and add 32.
Is a kilobyte 1000 or 1024 bytes?
Officially 1000 (kilo is the SI prefix); 1024 bytes is a kibibyte (KiB). In practice Windows and many upload forms mean 1024 when they say KB, and macOS since 10.6 means 1000. When a limit matters, stay 2 to 3% under it.
What is the difference between Mbit/s and MB/s?
Internet speeds are quoted in megabits per second; file sizes in megabytes. Divide Mbit/s by 8 to get MB/s: a 100 Mbit/s connection moves at most 12.5 MB/s, so a 500 MB video takes at least 40 seconds.
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Related references
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