About UnitSnap
A free unit converter that runs entirely in your browser and shows the factor behind every answer.
UnitSnap converts between 929 units across 80 categories, from the everyday ones to the units that only turn up in engineering and lab work. It is free, needs no account, and shows the working rather than only the answer.
How the numbers are worked out
Every unit on the site is defined against the SI base unit for its quantity, using the exact international agreements that sit underneath them. An inch is exactly 2.54 centimetres and a pound is exactly 0.45359237 kilograms, so those are the values used rather than rounded approximations.
Compound units are derived from those constants instead of being typed in by hand. A figure like pounds per cubic foot, or BTU per hour per square foot per degree Fahrenheit, is computed from the exact definitions of each part, which means the whole set stays internally consistent and cannot drift apart over time.
Conversions run at double precision in your browser. The Decimals control changes how the result is displayed and never changes the underlying value.
Everything happens on your device
There is no server doing the arithmetic. The converter is plain JavaScript that runs in the page, so the values you type stay on your device, and the page keeps working after you lose your connection. What that means for data is set out in the privacy policy.
What it deliberately does not do
There is no currency converter, because exchange rates need a live data feed and a stale rate is worse than no rate at all. There are no accounts, no saved history on our side, and no newsletter.
Corrections
If a factor looks wrong, it is worth telling us. Send the page address, the two units, the value you expected and where it comes from, and it will be checked against the defining standard. Write to hello@unitsnap.online or use the contact page.
Who runs it
UnitSnap is published by Romeck LLC. The site carries advertising, which is what pays for the domain and hosting; ads never change the numbers or the order in which converters are listed.