Unit Converter

About this Unit Converter

Convert values across length, weight, temperature, volume, area, speed, time, energy, pressure, power, angle, and digital data — over 100 units in 12 categories. Every conversion factor is hard-coded from NIST and ISO references; no network call is made when you type. Type once and read every target unit live, with adjustable precision and a localized decimal separator.

How does temperature conversion work?

Temperatures are non-linear: F = C × 9/5 + 32, K = C + 273.15, R = (C + 273.15) × 9/5, and Re = C × 4/5. The tool routes every input through Celsius internally, then expands to Fahrenheit, Kelvin, Rankine, and Réaumur, so you can read all five scales at once. Going below absolute zero (−273.15 °C / 0 K) triggers a warning instead of returning a misleading number.

Why is 1 GB different from 1 GiB?

Hard-disk vendors use SI prefixes — 1 GB equals 1,000,000,000 bytes. Operating systems often display memory and file sizes in IEC binary prefixes — 1 GiB equals 1,073,741,824 bytes. The two diverge by about 7.4% at the GB/GiB scale and grow further at TB/TiB. The tool always shows the SI column and the IEC column side by side so you never confuse the two systems.

How accurate are these conversions?

Every linear factor traces back to authoritative sources: 1 mile = 1609.344 m, 1 pound = 453.59237 g, 1 atmosphere = 101 325 Pa. The precision slider lets you read 1–15 significant figures; values smaller than 0.0001 or larger than 10¹⁵ automatically switch to scientific notation. The underlying math is pure JavaScript double-precision, the same precision the IEEE 754 standard guarantees.

Is my data sent anywhere?

Nothing leaves your browser. The conversion factors are bundled with the page, the math runs locally, and there is no analytics, no telemetry, and no API call. The URL hash updates as you type so you can bookmark or share a conversion, but only your browser sees the value.

Frequently asked

Why is 100 km/h not exactly 62 mph?

100 km/h is 62.137119 mph. The familiar '62 mph' rounds to two digits. We default to 6 significant figures so you see the precise value, but you can drop precision to 2 if you prefer a cleaner reading.

What is the difference between US and UK gallons?

A US gallon is 3,785.41 ml; a UK (imperial) gallon is 4,546.09 ml — about 20% larger. We list both separately so cross-Atlantic recipes don't go wrong.

Is 1 GB the same as 1 GiB?

No. 1 GB (gigabyte, decimal) = 1,000,000,000 bytes. 1 GiB (gibibyte, binary) = 1,073,741,824 bytes — a 7.4% difference that grows with scale. We always show both columns to remove ambiguity.

Why don't you support currency conversion?

Currency rates change minute by minute and require a network call to a real-time API, which would break our zero-network privacy promise. We may build a separate currency tool with explicit consent in the future.

Can I share a conversion with someone?

Yes — the URL hash updates as you change input, units, and precision. Copy the address bar and send it; the recipient lands on the same conversion in their browser.