iSmart Measure
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How to convert any unit
Convert length, mass, volume, temperature and more across US, UK and metric — live as you type, with every related unit shown at once.
The converter holds every value in canonical SI base units under the hood, then renders it live into US, UK and metric — so the same number is always consistent across systems.
Pick a category and type a value
Open Convert. Choose a category — Length, Area, Volume, Mass, Temperature and more (13 families in all). Type any number in the From field; there's no “convert” button, answers update live as you type.
Set the from and to units
Choose the unit you're converting from and to from the dropdowns, or tap the swap button to reverse them. The Quick start list offers common pairs like mi → km, lb → kg and °F → °C in one tap.
Read the live result and system equivalents
The converted value appears immediately (e.g. 1 mi = 1.60934 km), with the exact equation below it. A Metric equivalent strip and a live every-unit panel show the same value across related units at once. Adjust significant digits to taste.
Copy, save, or switch systems
Tap Copy to grab the result, Save to keep it, or use the US / UK / Metric switch at the top to reframe everything for your region. History keeps your recent conversions.
Following an American recipe abroad. Alex sees “1 mile to the trailhead” and “a 5-gallon cooler” in a US guide. Under Volume he taps the gal → L quick-start and reads 18.927 L; under Length, mi → km gives 1.60934 km. He flips the top switch to Metric so the rest of the guide reframes automatically.
Use the Quick start pairs (mi → km, lb → kg, °F → °C) to skip the dropdowns for the conversions you do most.
Frequently asked questions
How many unit categories are there?
Thirteen families — length, area, volume, mass, temperature, pressure, energy, power, speed, angle, data, electrical and fuel economy.
Do I have to press a convert button?
No. Results update live as you type, and a panel shows the value across every related unit simultaneously.
Are the conversions accurate?
Yes. Values are held in canonical SI base units and use factors sourced from NIST SP 811 and the BIPM SI Brochure, with exact factors where defined.
Is the converter free?
Yes — the unit converter is part of the free core of iSmart Measure, with no account required.