Unit Converter — Free Online Tool
Convert length, weight, area, volume, speed & more. · No signup · Works on mobile
100% private: your data is processed in your browser. Nothing is uploaded to our servers.
How to use the unit converter
-
1
Pick a category — length, weight, temperature, area, volume, speed, data, or time.
-
2
Select the unit you have and the unit you want.
-
3
Type your value; the converted result appears instantly and updates live.
What does this tool do?
This free unit converter handles eight measurement categories in one tool: length, weight/mass, temperature, area, volume, speed, data storage, and time. Pick a category, choose your from/to units, and the conversion happens instantly as you type — with results precise to 6 significant digits.
How does the unit converter work?
Every unit is defined by its exact ratio to a base SI unit (e.g. 1 mile = 1609.344 metres, fixed by international agreement in 1959). Conversion multiplies your value into the base unit and out to the target. Temperature uses offset formulas instead, since scales don't share a zero.
Frequently Asked Questions
What are the most common unit conversions?
The everyday staples: 1 inch = 2.54 cm, 1 mile = 1.609 km, 1 kg = 2.2046 lb, 1 US gallon = 3.785 L, 1 acre = 4,047 m². Cooking adds 1 cup = 240 ml and 1 oz = 28.35 g. This tool covers all of these plus 100+ more units.
Why is a US gallon different from a UK gallon?
The US kept the older wine gallon (3.785 L) after independence, while Britain redefined the imperial gallon as 4.546 L in 1824 — a 20% difference. The same split affects fluid ounces and pints, which is why UK fuel economy figures look better than US ones for identical cars.
Is the unit converter really free?
Yes — 100% free with no hidden charges, trial limits, or premium tiers for core features. You don't need to create an account or enter an email address. The site is supported by non-intrusive display ads, which keeps every tool free for everyone.
Is my data private when using the unit converter?
Completely. The unit converter runs entirely in your browser using JavaScript — nothing you type or upload is sent to our servers. When you close the tab, your data is gone. This makes it safe for confidential documents, financial figures, and personal information.
Does the unit converter work on mobile phones?
Yes. The unit converter is built mobile-first and works on any phone or tablet with a modern browser — iPhone (Safari), Android (Chrome), and everything in between. The layout adapts to small screens, so buttons and inputs stay easy to tap on a 375px-wide display.
Do I need to install anything to use the unit converter?
No. The unit converter works directly in your web browser — no downloads, no extensions, no signup. Just open the page, use the tool, and get your result instantly. It works on Windows, macOS, Linux, ChromeOS, iOS, and Android.