Convert length, weight, temperature and more as you type.
Inches become centimeters when a paper size, a TV or monitor diagonal, or a tool or pipe size is given in inches and you are measuring with a metric tape. This page opens with 12 in typed in, which gives 12 in = 30.48 cm, the length of a standard 12 inch ruler. A 27 in monitor diagonal is 27 in = 68.58 cm. Because one inch is defined as exactly 2.54 cm, both results are exact; the display would only round them if they ran past 6 significant digits. The formula is a single multiplication by 2.54. A screen size is a diagonal, so the 68.58 cm is the corner-to-corner length, not the width of the monitor; the width needs the aspect ratio, which this tool does not know. Likewise, a tool or a pipe sold by a nominal size in inches is often not that size when measured, so check the maker's table before you rely on a conversion. Edit the centimeter box if you would rather start from a metric measurement.
Every unit in a category is a fixed multiple of one base unit: meters for length, kilograms for mass, liters for volume, bytes for data. To convert, the tool multiplies your value by the size of the unit you start from and divides by the size of the unit you want. That is why the formula line says Multiply by or Divide by one number, such as Multiply by 2.54 for inches to centimeters. Temperature is the exception, because the scales start at different points, so it goes through degrees Celsius with an offset: 98.6 °F is 98.6 minus 32, times 5/9, which is exactly 37 °C. The arithmetic uses exact fractions rather than floating point numbers, so you never see an artefact such as 0.30000000000000004. Only the answer is rounded, once, to 6 significant digits, and trailing zeros are dropped. Typing in either box updates the other, and Swap exchanges the two units and moves the shown result into the first box.
The factors are the defined values, not rounded ones. One inch is exactly 0.0254 m, one foot 0.3048 m, one yard 0.9144 m and one mile 1609.344 m. One pound is exactly 0.45359237 kg and one ounce 28.349523125 g. One acre is 4046.8564224 m². One nautical mile is 1852 m and one knot is 1852 meters per 3600 seconds. One US gallon is 3.785411784 L and one imperial gallon is 4.54609 L. A year is taken as 365 days, and there is no month because months differ in length. The displayed answer keeps 6 significant digits, so a long result is rounded and the last digit is not a measurement. Outside 1e-6 to 1e15, numbers appear in a form like 1.5e-9. You can type the same form, such as 2.5e3. Commas are not accepted, so write 1234.5 and not 1,234.5.
Several unit names mean different amounts in the United States and in the imperial system, so this tool never picks one for you. Gallons, quarts, pints and fluid ounces are each listed twice, labelled US or imperial: a US gallon is 3.785411784 L and an imperial gallon is 4.54609 L, about 20 percent larger. The cup, tablespoon and teaspoon offered are the US ones. Three tons are listed with their meaning in the name: the metric tonne of 1000 kg, the US short ton of 2000 lb and the imperial long ton of 2240 lb. When a recipe, a fuel figure or a shipping document gives only a gallon or a ton, check which system its country uses before you convert, because the tool can only convert the unit you choose.
Data units come in two families with similar names. The decimal (SI) family counts in thousands: 1 kB is 1000 bytes, 1 MB is 1000 kB and 1 GB is 1000 MB. The binary (IEC) family counts in 1024s and has its own names: 1 KiB is 1024 bytes, 1 MiB is 1024 KiB and 1 GiB is 1024 MiB. The two differ by about 7 percent at the gigabyte level, since 1 GiB is 1.07374 GB. Both are listed under separate headings, and each name states its byte count, such as kilobyte (kB, 1,000 bytes) and kibibyte (KiB, 1,024 bytes), so the choice is yours. Bits are listed too, at 8 bits to a byte. This is a unit converter only: it does not read file sizes from your device.
The diagonal is 27 in = 68.58 cm. That is the corner-to-corner length of the screen. The width and height depend on the aspect ratio, for example a 16:9 panel is narrower than 68.58 cm, and this tool does not calculate them.
Yes for typical values. An inch is defined as exactly 2.54 cm, so 12 in is exactly 30.48 cm. The display shows 6 significant digits, so a long input such as 1234.5678 in is rounded to 3135.8 cm.
Because the inch is defined that way: it is exactly 0.0254 m, not a measured value. So 1 in = 2.54 cm with no rounding, and 12 in = 30.48 cm. The tool uses that definition, which is why the answer shows 2.54 and not 2.5400001.
Both are offered and each is labelled. A US gallon is 3.785411784 L and an imperial gallon is 4.54609 L. The same holds for the quart, the pint and the fluid ounce. Pick the one your source uses; the tool never chooses for you.
A kilobyte (kB) is 1000 bytes and a kibibyte (KiB) is 1024 bytes. The same split applies to MB and MiB, and GB and GiB. 1 GB is 1000 MB, while 1 GiB is 1024 MiB. Both families are listed under their own headings in the Data storage category.
Up to 6 significant digits, with trailing zeros removed. 1 kg is 2.20462 lb, and the exact figure continues past that. Whole numbers above 6 digits are rounded too, so 1234567 shows as 1234570. What you type is never reformatted.
No. Use digits with an optional minus sign, one dot for decimals and, if you like, an exponent such as 1.5e3. Commas and spaces inside a number are rejected with a message, because 1,234 could mean one thousand or one point two three four.
No. Currency needs live rates, and cups to grams depends on the ingredient, so both are out of scope. The tool converts units of the same kind only. It does offer US cups, tablespoons and teaspoons as volumes, which convert to milliliters and liters.
Yes, once the page has loaded. The conversion runs in your browser and needs no connection. Nothing you type is uploaded, saved or sent to the analytics; only the category and your last unit choices are remembered on this device.