How to use the unit converter
- Choose a category, such as length or temperature.
- Pick the "from" and "to" units.
- Type a number in either box. The other box updates as you type, so you can convert in both directions without swapping.
- Use Swap units to flip the pair. The table on the right lists common conversions for the category.
Results show up to 12 significant digits, with rounding noise removed. You can type numbers with commas, such as 1,25,000 or 1,250,000.
Exact conversion factors
Since 1959, the inch, foot, yard, mile and pound have been defined exactly in metric units. US and imperial gallons are also exact. This converter uses these definitions, not rounded values:
| Unit | Exact value |
|---|---|
| 1 inch | 2.54 cm |
| 1 foot (12 in) | 30.48 cm |
| 1 mile | 1.609344 km |
| 1 nautical mile | 1,852 m |
| 1 pound | 0.45359237 kg |
| 1 ounce (1/16 lb) | 28.349523125 g |
| 1 US gallon | 3.785411784 L |
| 1 imperial (UK) gallon | 4.54609 L |
| 1 square foot | 0.09290304 m² |
| 1 acre | 4,046.8564224 m² |
| 1 standard atmosphere | 101,325 Pa |
Every other factor follows from these. For example, 1 square foot is 0.3048 m × 0.3048 m = 0.09290304 m², and 1 psi is one pound-force (0.45359237 kg × 9.80665 m/s²) per square inch, about 6,894.76 Pa.
Temperature formulas
Example: 37 °C × 9/5 + 32 = 66.6 + 32 = 98.6 °F. Temperature is the one category where you can't just multiply, because the scales start at different zero points.
KB vs KiB: decimal and binary data sizes
Storage makers use decimal prefixes: 1 kB = 1,000 bytes and 1 GB = 1,000,000,000 bytes. Many operating systems count in powers of 1,024 and should label the result KiB, MiB or GiB. That is why a "1 TB" drive shows as about 931 GiB.
| Decimal (SI) | Bytes | Binary (IEC) | Bytes |
|---|---|---|---|
| kilobyte (kB) | 1,000 | kibibyte (KiB) | 1,024 |
| megabyte (MB) | 1,000² | mebibyte (MiB) | 1,024² |
| gigabyte (GB) | 1,000³ | gibibyte (GiB) | 1,024³ |
| terabyte (TB) | 1,000⁴ | tebibyte (TiB) | 1,024⁴ |
Internet speeds are quoted in bits, not bytes. A 100 Mb/s connection moves at most 12.5 MB per second, because 1 byte is 8 bits.
Lakh, crore and Indian units
In India, large numbers are grouped as 1,00,000 (one lakh) and 1,00,00,000 (one crore). One lakh is 100,000, so 10 lakh is 1 million. One crore is 10 million, and 100 crore is 1 billion. Choose the Number category to convert between them.
Flats and offices in India are usually sold by the square foot: 1,000 ft² is about 92.9 m². Land is often measured in acres or hectares (1 hectare is about 2.471 acres). Regional land units such as bigha, guntha and kanal are not included, because their size differs from state to state. Check the local definition with your land records office.
The tola, used for gold, is 180 grains, or about 11.66 g. Jewellers today usually quote gold per 10 grams.
Tips
- US or UK? Recipes and fuel figures from the US use US gallons, cups and fluid ounces, which are smaller than the imperial ones.
- Stone is 14 pounds, about 6.35 kg. It is still used for body weight in the UK and Ireland.
- Months and years here are averages of the Gregorian calendar. For exact gaps between dates, use the date calculator.
Frequently asked questions
How many centimetres are in an inch?
How do I convert kg to pounds?
How many square feet are in a square metre?
What is the difference between a US gallon and an imperial gallon?
How many lakh are in a million?
Why does my 1 TB drive show 931 GB?
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