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120+ converters and calculators. Type a value, get the answer while you type — with the formula to back it up.
Universal unit converter
All categories
The unit converter that answers before you finish typing
This free online unit converter covers 120+ conversions across length, weight, temperature, volume, area, speed, time, digital storage, pressure, power and more. Convert centimeters to inches, kilograms to pounds, Celsius to Fahrenheit or liters to gallons — the result appears instantly, while you type.
Every conversion uses the exact legal definition of each unit — one inch is exactly 25.4 millimeters, one pound is exactly 453.59237 grams. Rounding only happens on screen, never in the math, so a value survives converting back and forth without drifting.
All calculations run locally in your browser: nothing is sent to a server, nothing is logged, and every conversion calculator works just as fast on your phone as on your desktop. Each tool page includes the formula, a conversion table and worked examples, so you can check any result by hand.
Frequently asked questions
How does this unit converter work?
Pick a category, choose the units to convert from and to, and type a value. The conversion is calculated instantly in your browser using exact conversion factors — no page reload, no server round-trip.
Which unit conversions are supported?
Over 120 converters across 12 categories: length (cm, inches, feet, meters, km, miles), weight (kg, lbs, grams, ounces, stone), temperature (Celsius, Fahrenheit, Kelvin), volume and cooking (liters, gallons, cups, tablespoons), area, speed, time, digital storage, numbers (Roman numerals, binary, hex), pressure, power and energy.
How accurate are the conversions?
Conversions use exact international definitions where they exist — 1 inch = 25.4 mm, 1 pound = 453.59237 g, 1 US gallon = 3.785411784 L. Results are displayed to 7 significant digits; the underlying math is not rounded.
Is this converter free?
Yes. Every converter and calculator on this site is free, with no sign-up and no limits. Calculations happen on your device, so the tools stay fast even on a slow connection.