Free Unit Converter Online ๐
Convert length, weight, temperature, area, volume, speed, data, time, energy, pressure, power & cooking units instantly. Metric & imperial supported.
Free Unit Converter Online — Metric & Imperial Measurement Converter
Our free online unit converter supports 12 measurement categories and over 80 units — covering length, weight, temperature, area, volume, speed, digital data, time, energy, pressure, power, and cooking measurements. Whether you need a quick metric converter online for a science class, an imperial to metric conversion for a recipe, or a data storage converter for an IT project, this universal unit converter handles all of it with instant results, formula display, and a one-click copy button.
Length Converter — Miles to Kilometers, Feet to Meters & More
The length converter supports meters, kilometers, centimeters, millimeters, micrometers, nanometers, miles, yards, feet, inches, nautical miles, and light years. Common conversions: 1 mile = 1.60934 km, 1 foot = 0.3048 meters, 1 inch = 2.54 cm, 1 nautical mile = 1.852 km. The metric system for length is based on the meter (m) and uses prefix multipliers (kilo = ×1000, centi = ×0.01, milli = ×0.001). The imperial system uses inches, feet, yards, and miles — still the primary system in the United States for everyday distance.
Weight Converter — Pounds to Kilograms, Ounces to Grams
The weight and mass converter covers kilograms, grams, milligrams, micrograms, metric tons, pounds, ounces, stones, and US short tons. Key conversions: 1 kg = 2.20462 lbs, 1 pound = 453.592 grams, 1 stone = 14 pounds = 6.35 kg, 1 metric ton = 1000 kg = 2204.62 lbs. Weight conversion is used daily for nutrition labeling, international shipping, medical dosing, and cooking. The UK and US use different definitions of "ton" — the US short ton is 2000 lbs (907 kg), the UK long ton is 2240 lbs (1016 kg), and the metric tonne is 1000 kg (2204 lbs).
Temperature Converter — Celsius to Fahrenheit to Kelvin
Temperature conversion uses formulas rather than multiplication factors. Celsius to Fahrenheit: °F = (°C × 9/5) + 32. Fahrenheit to Celsius: °C = (°F − 32) × 5/9. Celsius to Kelvin: K = °C + 273.15. Key reference points: 0°C = 32°F (water freezes), 100°C = 212°F (water boils), 37°C = 98.6°F (body temperature), −40°C = −40°F (they are equal at this point), 0K = −273.15°C (absolute zero). Kelvin is used in physics, chemistry, and astronomy — it is an absolute scale with no negative values.
Data Storage Converter — MB to GB, GB to TB
The data storage converter uses the binary (base-1024) system used by operating systems. 1 KB = 1024 bytes, 1 MB = 1024 KB, 1 GB = 1024 MB, 1 TB = 1024 GB, 1 PB = 1024 TB. Common conversions: 2048 MB = 2 GB, 500 GB = 0.488 TB, 1 TB = 1024 GB = 1,048,576 MB. Note that hard drive manufacturers use decimal (base-1000) for labeling — so a "1 TB" drive shows as 931 GB in Windows or macOS because the OS uses binary calculation. This converter uses the binary system standard for accurate OS-matching results.
Cooking Measurement Converter — Cups, Tablespoons, Teaspoons
The cooking measurement converter helps home cooks and professional chefs scale recipes and convert between US customary and metric cooking units. Key conversions: 1 cup = 16 tablespoons = 48 teaspoons = 8 fl oz = 236.6 mL, 1 tablespoon = 3 teaspoons = 14.79 mL, 1 liter = 4.23 cups. This is especially useful when following a European recipe that uses grams and milliliters while your measuring tools are in cups and ounces, or when scaling a recipe from 4 servings to 12.
What Makes This Unit Converter Different?
Most free unit converters show a result number with no context. This tool adds a formula display showing exactly how the conversion was calculated, quick reference cards for common conversions in the selected category, a one-click copy button, and a swap button to instantly reverse the direction. It covers 12 categories with 80+ units — significantly more than most free tools — and all conversions run instantly in the browser with no server calls.
Frequently Asked Questions
How do I convert miles to kilometers online?
Select Length category, choose Mile (mi) as From and Kilometer (km) as To. Formula: 1 mile = 1.60934 km. So 5 miles = 8.047 km, 26.2 miles (marathon) = 42.2 km.
How do I convert Celsius to Fahrenheit?
Select Temperature, choose °C as From and °F as To. Formula: °F = (°C × 9/5) + 32. Key points: 0°C = 32°F, 100°C = 212°F, 37°C = 98.6°F (body temp).
How do I convert pounds to kilograms?
Select Weight, choose Pound (lb) as From and Kilogram (kg) as To. Formula: 1 lb = 0.453592 kg. So 150 lbs = 68.04 kg. Reverse: 1 kg = 2.20462 lbs.
What is the difference between metric and imperial units?
Metric (SI) uses base-10 — meters, kilograms, liters, Celsius — used by most of the world. Imperial uses miles, pounds, gallons, Fahrenheit — primarily used in the United States. This converter supports both systems.
How do I convert megabytes to gigabytes?
Select Data category, choose MB as From and GB as To. Formula: GB = MB ÷ 1024. So 2048 MB = 2 GB, 500 MB = 0.488 GB. Uses binary (base-1024) standard matching OS display.
Can I convert cooking measurements like cups to tablespoons?
Yes. Select Cooking category. 1 cup = 16 tablespoons = 48 teaspoons = 236.6 mL. Useful for scaling recipes or converting between US and European cooking units.
About This Tool
This Unit Converter was built by the FreeImageTools team — scientists, engineers, developers, and home cooks who convert units daily across work and life. The original tool had 8 categories with minimal units. We expanded it to 12 categories with 80+ units, added a formula display showing the conversion method, quick reference cards for common conversions, a copy result button, a swap button to reverse direction instantly, and improved the UI for clarity and mobile use. All conversions run in the browser. Reviewed and tested in July 2026.