Unit Converter

How this works

Every unit in a category converts through one shared base unit — meters for length, grams for weight, and so on — so any pair of units can convert accurately without needing a lookup table for every possible combination. Temperature works the same way using Celsius as its base, which is why Fahrenheit and Kelvin still convert correctly between each other even though neither is the category's reference unit. The reference table below the converter runs that same conversion against every other unit in the category simultaneously, so switching the “to” unit is rarely even necessary.

FAQ

Which unit categories does this cover?

Length, weight, temperature, volume, area, speed, time, and digital storage (bits through terabytes) — the categories people actually look up day to day, rather than every obscure unit that's ever existed.

How accurate are the conversions?

All conversion factors are the exact, standard definitions (for example, 1 inch = 2.54 cm and 1 pound = 453.59237 g exactly), not rounded approximations. The one exception is calendar-based time units — a "month" is averaged at 30.44 days and a "year" at 365.25 days, since actual months and years vary in length.

Kilobytes and megabytes — is this 1000-based or 1024-based?

This uses the decimal (1000-based) definitions — the same ones used for file sizes on macOS, in networking, and on storage device packaging — since that's what most people mean by KB/MB/GB day to day. Some contexts (older Windows file properties, RAM) use the binary 1024-based definitions instead (formally called KiB, MiB, GiB), which will read a few percent higher for the same amount of data.

Why does the reference table update as I type?

Instead of showing just one conversion at a time, it converts your value into every other unit in the category at once — so if you're not sure whether you need feet or yards, you can see both without switching back and forth.