Free Unit Converter Online
Convert length, weight, temperature, volume, area, speed, time, data and more. Choose a calculator below or search the directory for the exact conversion you need.
Find a converter
Search by category or conversion phrase, such as “cm to inches” or “kg to lbs”.
Length Converter
Convert length between centimeters, inches, feet, meters, kilometers, and miles instantly with live multi-unit results.
Weight Converter
Convert weight between kilograms, pounds, ounces, grams, and stones instantly with live multi-unit result tables.
Temperature Converter
Convert temperatures between Celsius, Fahrenheit, and Kelvin instantly with accurate formulas and live multi-scale output.
Volume Converter
Convert volume between liters, milliliters, gallons, quarts, cups, and ounces instantly with live multi-unit results.
Currency Converter
Convert currencies between USD, EUR, GBP, CAD, and more with live exchange rates and a clean multi-currency comparison view.
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Unit Conversion Guide
Looking for a quick conversion instead of a long formula? Use the directory above for common metric, U.S. customary, and other measurement conversions. High-demand searches include cm to inches, inches to cm, kg to lbs, pounds to kg, Celsius to Fahrenheit, feet to meters, and miles to kilometers.
Length conversions
Inches ↔ centimeters, feet ↔ meters, miles ↔ kilometers, yards, and more.
Weight & mass
Kilograms ↔ pounds, grams ↔ ounces, and other everyday mass conversions.
Temperature
Celsius ↔ Fahrenheit and other temperature scales for weather, science, and cooking.
Volume & capacity
Liters ↔ U.S. gallons, milliliters, cups, quarts, and related capacity units.
Metric vs. customary
Switch between decimal metric units and commonly used U.S. customary measurements.
Everyday & technical use
Use unit conversions for school, engineering, construction, travel, fitness, cooking, and DIY work.
Quick reference
Standard reference relationships are used for common measurements; the U.S. and Imperial systems can differ for some units, especially volume.
Unit Converter FAQ
Answers to common questions about metric, U.S. customary, Imperial, and everyday unit conversions.
What is a unit converter?
A unit converter changes a measurement from one unit into an equivalent value in another unit, such as centimeters to inches, kilograms to pounds, or Celsius to Fahrenheit.
How do I convert units online?
Choose the conversion tool that matches your measurement, enter the value, and select the source and target units. OneStepKit's converter pages are designed to show the result as you enter the value.
How many centimeters are in an inch?
Exactly 2.54 centimeters equal 1 inch. For quick conversions, multiply inches by 2.54 to get centimeters.
How do I convert centimeters to inches?
Divide centimeters by 2.54 to get inches. For example, 10 cm is about 3.937 inches.
How do I convert kilograms to pounds?
Multiply kilograms by about 2.20462 to get pounds. For example, 5 kg is about 11.0231 lb.
How do I convert pounds to kilograms?
Multiply pounds by 0.45359237 to get kilograms. For example, 10 lb is about 4.5359 kg.
How do I convert Celsius to Fahrenheit?
Use the formula Fahrenheit = (Celsius × 9/5) + 32. For example, 20°C is 68°F.
How do I convert Fahrenheit to Celsius?
Use the formula Celsius = (Fahrenheit − 32) × 5/9. For example, 68°F is 20°C.
How do I convert feet to meters?
Multiply feet by 0.3048 because 1 foot equals exactly 0.3048 meters. For example, 6 ft is 1.8288 m.
How do I convert miles to kilometers?
Multiply miles by 1.609344 to convert to kilometers. For example, 10 miles is 16.09344 km.
How do I convert liters to gallons?
For U.S. liquid gallons, multiply liters by about 0.264172. Imperial gallons use a different conversion factor, so choose the correct gallon standard when a converter offers both.
Is a unit converter accurate?
The result depends on the conversion constant and the rounding displayed by the individual converter. Standard measurement relationships are used for common metric and U.S. customary conversions.
What is the difference between metric and imperial units?
Metric units are based on the SI measurement system and decimal scaling. U.S. customary and Imperial systems use units such as inches, feet, miles, pounds, ounces, gallons, and Fahrenheit, with some differences between U.S. and Imperial volume units.
Can I use a unit converter for engineering, school, cooking, or everyday measurements?
Yes. Unit conversions are useful for schoolwork, engineering and technical calculations, cooking measurements, fitness, travel, construction, DIY projects, and everyday measurements. Always confirm the unit standard when the distinction matters.
Is the OneStepKit unit converter free?
The converter directory is free to use online. Each individual converter page shows the units and features supported by that tool.