Unit Converter

How it works

Pick a category, choose the unit you’re converting from and the unit you want, and the result updates as you type. Every calculation runs in your browser using precise conversion factors, so there is no lookup to a server and no delay. Linear units — length, weight, volume, area, speed and data — are converted through a common base unit, while temperature uses its own formulas because the scales have different zero points.

Categories covered

The converter handles length (from millimetres to miles), weight and mass (milligrams to stones), temperature (Celsius, Fahrenheit, Kelvin), volume (millilitres to US gallons, including cooking measures), area (square metres to acres), speed (m/s, km/h, mph, knots) and digital storage. For data, both decimal units (KB, MB, GB — powers of 1000) and binary units (KiB, MiB, GiB — powers of 1024) are included, so you can convert correctly depending on which convention a device or file size uses.

How to convert units

Select the category that matches what you are measuring — length, weight, temperature, volume, area, speed or data — and the unit lists rebuild to show only that category’s units. Type the value in the Value field: the result appears instantly below as value from-unit = result to-unit. Press the ⇅ button between the From and To selectors to reverse the conversion in one click.

A concrete example

Say you want to know how far 5 miles is in kilometres. Choose Length, keep Mile (mi) in the From field and select Kilometer (km) as the target — the tool immediately shows 5 Mile (mi) = 8.04672 Kilometer (km). The same flow works for cooking (2 Cup (US) = 473.176 Milliliter (ml)) or for checking a drive’s real capacity against its label (250 Gigabyte (GB) = 232.83064 Gibibyte (GiB)). One press of the ⇅ button reads the inverse conversion instead.

What to expect

Results are formatted for readability: in the common range, up to eight significant figures with trailing zeros removed, and scientific notation for very large or very small values. A zero input stays a clean 0, and a missing or invalid number shows a dash rather than a misleading figure. Every line keeps the full unit name, so the meaning is visible at a glance. Conversion factors follow standard definitions, so the output is reliable for everyday use and most technical needs; for legal or scientific work that requires certified precision, always verify against an authoritative reference.

Common problems and fixes

The result shows a dash. The Value field is empty or does not hold a valid number — type or correct it and the result returns immediately. The output looks like 1.23e+15. That is scientific notation, applied automatically to very large or very small values, and it is still exact. A data conversion seems off. Check whether decimal (KB, MB, GB) or binary (KiB, MiB, GiB) units are the right convention for what you are measuring — many devices report binary sizes under decimal labels. The unit you need is missing. Only the units listed for each category exist; the selectors are rebuilt from that exact list whenever you change category.

Frequently asked questions