Unit Converter
Convert between units instantly
Free Online Unit Converter
Twelve categories, instant two-way conversion
Convert length, weight, temperature, area, volume, speed, time, data storage, ratio/concentration (ppm, ‰, %), pressure (bar, psi), energy (kcal, kJ, kWh) and power (kW, hp, PS), fuel economy (L/100 km, km/L, mpg) units in one fast, accurate tool. Whether you need inches to cm, kg to lbs, Celsius to Fahrenheit, km to miles or MB to GB, just pick a category, type a value, and the result appears instantly. You can type in either field to convert in both directions and use the swap button to reverse the units. Every calculation runs locally in your browser with precise conversion factors, so results stay accurate and nothing you enter is uploaded.
Features
Thirteen Categories
Length, weight, temperature, area, volume, speed, pressure, energy, power, fuel economy, time, data and ratio.
Two-Way
Type in either field; swap units with one click.
Accurate
Precise conversion factors and correct temperature formulas.
Private & Free
Everything runs locally in your browser.
Popular Conversions
Length
- 1 inch = 2.54 cm
- 1 foot = 30.48 cm
- 1 yard = 0.9144 m
- 1 mile = 1.609 km
- 1 nautical mile = 1.852 km
Weight
- 1 kg = 2.2046 lb
- 1 pound = 453.59 g
- 1 ounce = 28.35 g
- 1 stone = 6.35 kg
- 1 metric ton = 1000 kg
Temperature
- °F = °C × 9/5 + 32
- °C = (°F - 32) × 5/9
- K = °C + 273.15
- 0 °C = 32 °F
- 100 °C = 212 °F
Speed
- 1 km/h = 0.6214 mph
- 1 mph = 1.609 km/h
- 1 m/s = 3.6 km/h
- 1 knot = 1.852 km/h
Volume
- 1 liter = 0.2642 gallon
- 1 gallon = 3.785 L
- 1 cup = 236.6 mL
- 1 fl oz = 29.57 mL
Data
- 1 byte = 8 bit
- 1 KB = 1024 B
- 1 MB = 1024 KB
- 1 GB = 1024 MB
- 1 TB = 1024 GB
Ratio / Concentration
- 1 % = 10 ‰
- 1 ‰ = 10 ‱
- 1 ‱ = 10 pcm
- 1 pcm = 10 ppm
- 1 ppm = 1,000 ppb
- 1 ppb = 1,000 ppt
Pressure
- 1 bar = 14.504 psi
- 1 psi = 0.06895 bar
- 1 atm = 1.01325 bar = 14.696 psi
- 1 bar = 100 kPa
- 1 mmHg = 133.32 Pa
Energy
- 1 kcal = 4.184 kJ
- 1 kJ = 0.239 kcal
- 1 kWh = 3,600 kJ
- 1 BTU = 1.055 kJ
Power
- 1 hp = 0.7457 kW
- 1 PS = 0.7355 kW
- 1 kW = 1.341 hp = 1.360 PS
- 1 kW = 3,412 BTU/h
Frequently Asked Questions
How accurate is the converter?
It uses standard, precise conversion factors and shows up to seven significant digits, which is accurate for everyday and most professional needs.
How many centimeters are in an inch?
One inch equals exactly 2.54 cm. To convert inches to centimeters multiply by 2.54; to go from centimeters to inches divide by 2.54.
How many pounds is 1 kilogram?
One kilogram is about 2.2046 pounds. Multiply kilograms by 2.2046 to get pounds, or divide pounds by 2.2046 to get kilograms.
How do I convert kilometers to miles?
Multiply kilometers by 0.6214 to get miles, or multiply miles by 1.609 to get kilometers. For example, 10 km is about 6.21 miles.
How does temperature conversion work?
Temperatures are converted through Celsius using the correct formulas, so Celsius, Fahrenheit and Kelvin all convert exactly.
Can I convert in both directions?
Yes. Type a value in either box and the other updates automatically. The swap button flips the two units.
Do you store what I enter?
No. All conversions happen in your browser and nothing you type is uploaded.
What is the difference between hp and PS?
Mechanical horsepower (hp), used in the US and UK, is 745.7 W. Metric horsepower (PS in German, CV in Spanish, ch in French) is 735.5 W, about 1.4% smaller. So 100 PS = 98.6 hp = 73.5 kW, and 1 kW = 1.341 hp = 1.360 PS.
How do I convert L/100 km to mpg?
Fuel economy units are inversely proportional, so there is no simple factor: mpg (US) = 235.215 ÷ L/100 km and mpg (UK) = 282.481 ÷ L/100 km. km/L = 100 ÷ L/100 km. Choose “Fuel economy” in the converter to do it automatically.