Unit Converter
Convert between any units of length, weight, temperature, volume, area, speed, and time
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Quick summary
A unit converter converts measurements between different units within the same physical quantity. Most conversions work by converting to a base unit (e.g., meters for length, kilograms for mass) and then to the target unit. Temperature is a special case using affine (non-multiplicative) formulas.
Reviewed by Simple Calculators TeamLast reviewed
How to use this calculator
- Enter the inputs requested by the calculator.
- Choose the units or options that match your situation and review the assumptions.
- Run or update the calculation to see the result.
- Review the result, breakdown, and formulas shown on the page.
- Check the inputs, units, dates, and limitations before saving or sharing the result.
Unit Conversion Formulas
Temperature Conversion
- °C
- Celsius (base unit)
- °F
- Fahrenheit
- K
- Kelvin
Worked example
Convert 100°C to Fahrenheit
- Given
- °C = 100
- Calculation
- Result
- = 212°F
Length Conversion (Metric–Imperial)
- in
- 1 inch = 2.54 centimeters
- mi
- 1 mile = 1.609344 kilometers
Worked example
Convert 5 miles to kilometers
- Given
- mi = 5
- Calculation
- Result
- = 8.047 km
Frequently asked questions
How do I convert Celsius to Fahrenheit?
°F = (°C × 9/5) + 32. For quick mental math: double the Celsius, subtract 10%, then add 32. For example, 25°C: 25×2=50, 50-5=45, 45+32=77°F (exact: 77°F).
How many feet are in a meter?
1 meter = 3.28084 feet (approximately). Or: 1 foot = 0.3048 meters exactly. So 5 meters = 5 × 3.28084 ≈ 16.404 feet.
What is the difference between a UK and US gallon?
The US gallon = 3.785411784 liters exactly. The imperial (UK) gallon = 4.54609 liters. This converter uses the US gallon. So 1 US gallon ≈ 0.833 UK gallons.
How do you convert kg to pounds?
1 kg = 2.20462 pounds. So 70 kg = 70 × 2.20462 ≈ 154.32 lb. In reverse: 1 lb = 0.45359237 kg exactly.
Key terms
- SI Units
- The International System of Units (metric system): meter, kilogram, second, Kelvin, etc.
- Imperial Units
- The measurement system used in the US: feet, miles, pounds, gallons, Fahrenheit.
- Base Unit
- The reference unit used internally for conversions (e.g., meters for length, kg for mass).
- Affine Conversion
- A conversion requiring addition/subtraction in addition to multiplication (e.g., temperature).
Methodology, sources & limitations
This page shows the formula, assumptions, and limitations used for this estimate. Rates, thresholds, and other time-sensitive inputs can change, so verify them against the relevant official source before relying on a result.
For our review approach and the primary sources we consult, see the methodology and source policy. If you spot an outdated figure or formula, please contact us with a correction.