Unit Converter

What is a unit converter?#

A unit converter turns a measurement in one unit into the same physical quantity expressed in another — 1 mile into 1.609344 kilometres, 100 °F into 37.78 °C, 1 GiB into 1024 MiB. Mechanically that is just arithmetic, but the details are where converters earn their keep: temperature has a non-zero offset (so it is not a simple multiplication), computer data has two parallel systems (binary KiB/MiB/GiB versus decimal KB/MB/GB, which differ by 7 percent at the gigabyte scale and quietly break storage estimates), and floating-point math leaves noise like 0.30479999 unless someone rounds it sensibly.

This page handles six categories — length, area, volume, temperature, data, and time — through a single base-unit pivot: every unit (except temperature) has a factor relative to a base, and conversion goes value × fromFactor ÷ toFactor. Temperature is special-cased because its zero point moves. Results are trimmed to a sensible number of significant digits so you read 1.609344 instead of 1.6093439999999998.

How to use it#

1. Pick a Category from the dropdown: length, area, volume, temperature, data, or time.
2. Enter the Value you want to convert.
3. Choose the From unit (the dropdown lists the symbols available for that category).
4. Choose the To unit. The arrow between them is a visual cue only.
5. The Output box shows the converted value live.

Key features#

• Six categories in one tool. Length (nm to miles plus nautical miles), area (mm² to acres and square miles), volume (millilitres to gallons, with US and UK gallons kept separate), temperature, data, and time — covering the everyday conversions without a dozen separate pages.
• Temperature handled correctly. Celsius, Fahrenheit, and Kelvin convert through their real offsets (e.g. C = (F − 32) × 5/9, K = C + 273.15), not by multiplication — so 0 °C correctly becomes 32 °F and 273.15 K, not zero.
• Binary and decimal data units side by side. KiB/MiB/GiB/TiB/PiB use the 1024 base; KB/MB/GB/TB/PB use the 1000 base. Both are listed so you can see why a “500 GB” drive shows as ~465 GiB in your OS.
• Float-noise trimming. Results are rounded to up to 8 significant digits with trailing zeros stripped, so 1 ft → 0.3048 m rather than 0.30479999999999996 m; very large or tiny results switch to exponential notation automatically.
• US vs UK gallons. The US gallon (3.785 l) and the imperial gallon (4.546 l) are distinct entries, not folded into one wrong number.

Worked example#

Convert 1 mile to kilometres: set Category length, Value 1, From mi, To km:

1 mi = 1.609344 km

Switch to temperature — 100 °F to °C:

100 °F = 37.77778 °C

That is the offset at work: subtract 32, multiply by 5/9. A naive “multiply by a factor” converter would give you a wildly wrong answer here, because Fahrenheit’s zero is not absolute zero.

Now the data trap. Convert 1 GiB (binary) three ways:

1 GiB = 1024 MiB
1 GiB = 1073741824 B
1 GiB = 1.073741824 GB   (decimal)

The last line is the one that bites in practice: a vendor’s “500 GB” disk is 500 decimal gigabytes, which your operating system — measuring in binary GiB — reports as roughly 465 GiB. Same bytes, two conventions, a 7 percent gap.

FAQ#

Why does my OS show fewer gigabytes than the box promised?#

Because disk vendors use decimal units (1 GB = 10⁹ bytes) and operating systems traditionally use binary units (1 GiB = 2³⁰ bytes = ~1.074 × 10⁹). A “500 GB” disk is 500 × 10⁹ bytes, which is about 465 GiB. This page lets you convert between the two explicitly so the gap stops being a mystery.

Why is temperature converted differently from everything else?#

Because the zero points differ. 0 °C, 32 °F, and 273.15 K all describe the same temperature (the freezing point of water), so conversion must shift the zero point before scaling — (F − 32) × 5/9, or K = C + 273.15. Length, mass, and data all share a true zero, so a single multiply suffices. Mixing the two approaches is the classic unit-converter bug.

Why are US and UK gallons both listed?#

Because they are different volumes and using the wrong one ruins a recipe or a fuel calculation. The US liquid gallon is 3.785 litres; the imperial (UK) gallon is 4.546 litres — about 20 percent larger. They share a name but not a size, so the tool keeps them as separate units rather than silently averaging them.

How long is a “month” in the time category?#

A Julian month of 30.4375 days (exactly 365.25 / 12), and a Julian year of 365.25 days. These are the standard fixed-length averages used in scientific and financial calculations, because calendar months vary from 28 to 31 days and calendar years are 365 or 366. For a specific calendar span, count the actual days instead of converting through “month”.