Free Unit Converters
Convert between units of measurement instantly with our free online converters. From temperature and length to data storage and energy, each converter supports dozens of units and delivers precise results. All conversions happen in your browser — nothing is uploaded, and no signup is required.
All Converters
Temperature Converter
Convert between Celsius, Fahrenheit, and Kelvin.
Length Converter
Convert meters, feet, inches, miles, and more.
Weight Converter
Convert kg, pounds, ounces, stone, and tonnes.
Speed Converter
Convert mph, km/h, knots, and m/s.
Volume Converter
Convert liters, gallons, cups, tablespoons, and more.
Area Converter
Convert square meters, feet, acres, and hectares.
Data Storage Converter
Convert bytes, KB, MB, GB, TB, and PB.
Time Converter
Convert seconds, minutes, hours, days, and weeks.
Pressure Converter
Convert PSI, bar, ATM, pascal, and mmHg.
Energy Converter
Convert joules, calories, kWh, and BTU.
About Unit Conversion
Unit conversion is one of the most common daily tasks — from cooking with a recipe that uses metric measurements to understanding weather forecasts in an unfamiliar scale. The world uses two primary measurement systems: the metric system (meters, kilograms, Celsius) used by most countries, and the imperial system (feet, pounds, Fahrenheit) used primarily in the United States. Our converters bridge the gap between these systems instantly.
Each converter on Toolsium supports a wide range of units within its category. Simply enter a value, select your source and target units, and get an accurate result. All conversions are computed locally in your browser, so there is no server delay and your data stays private.
Which Converter Do You Need?
Here is a quick guide to our 10 unit converters and when each is most useful:
- Travel & weather: Temperature Converter (Celsius, Fahrenheit, Kelvin) and Speed Converter (mph, km/h, knots).
- Cooking & recipes: Volume Converter (cups, liters, tablespoons) and Weight Converter (grams, ounces, pounds).
- Construction & DIY: Length Converter (inches, centimeters, feet, meters) and Area Converter (sq ft, sq meters, acres).
- Technology: Data Storage Converter (bytes, KB, MB, GB, TB) for understanding file sizes and storage capacity.
- Science & engineering: Pressure Converter (PSI, bar, pascal), Energy Converter (joules, calories, kWh), and Time Converter (seconds to hours, days to weeks).
How Unit Conversion Works
Unit conversion relies on known ratios between measurement units. For example, 1 inch equals exactly 2.54 centimeters, and 1 kilogram equals approximately 2.20462 pounds. Our converters store these precise conversion factors and apply them instantly when you enter a value. For temperature conversions, the math involves formulas rather than simple ratios — for example, Fahrenheit to Celsius requires subtracting 32 and multiplying by 5/9.
All conversion factors used on Toolsium are based on internationally recognized standards from organizations like NIST (National Institute of Standards and Technology) and the International Bureau of Weights and Measures (BIPM).
Frequently Asked Questions
Our converters use standard conversion factors recognized by international measurement authorities. Results are displayed with up to 6 decimal places for precision. They are suitable for everyday use, education, and most professional applications.
The metric system (used worldwide) is based on powers of 10 — kilometers, meters, centimeters, millimeters. The imperial system (used mainly in the US) uses units like miles, yards, feet, and inches. Our converters handle both systems seamlessly.
Each converter lets you select any source and target unit from its full list. To compare multiple conversions, simply change the target unit after each conversion — results update instantly.
Yes. Once the page has loaded, all conversions are performed locally in your browser with no internet connection required.
Quick Conversion Reference
The most commonly searched conversions in one place:
| From | To | Factor | Tool |
|---|---|---|---|
| 1 inch | 2.54 cm | × 2.54 | Length |
| 1 foot | 30.48 cm | × 30.48 | Length |
| 1 mile | 1.609 km | × 1.609 | Length |
| 1 pound | 0.4536 kg | × 0.4536 | Weight |
| 1 kg | 2.205 lbs | × 2.205 | Weight |
| 1 US gallon | 3.785 liters | × 3.785 | Volume |
| 1 cup | 236.6 mL | × 236.6 | Volume |
| °F to °C | °C | (°F − 32) × 5/9 | Temperature |
| °C to °F | °F | °C × 9/5 + 32 | Temperature |
| 1 mph | 1.609 km/h | × 1.609 | Speed |
| 1 GB | 1,024 MB | × 1,024 | Data Storage |
| 1 PSI | 6,895 Pa | × 6,895 | Pressure |
Read our guide: Metric vs Imperial: The Complete Conversion Guide
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