Index
All ConvertHub converters
Twelve categories, 71 units and 132 one-way conversions. Each pair page includes the formula, worked examples and a chart.
Length
Length conversions cover the metric system, US customary units and nautical measures. The inch is defined as exactly 2.54 centimetres, which fixes every other imperial length unit.
Weight
Weight and mass conversions link the SI kilogram with the pound, the ounce and the stone. The international avoirdupois pound is exactly 0.45359237 kilograms.
Temperature
Temperature is the one category where conversion is not a multiplication: Celsius, Fahrenheit and Kelvin use offset formulas, so the relationship is affine rather than proportional.
Area
Area conversions matter for real estate, land and construction. One square metre is the SI base; hectares, acres and square feet are the units you meet in listings and deeds.
Volume
Volume conversions span cooking, chemistry and logistics. US and imperial gallons differ, so always check which gallon a recipe or spec refers to.
Speed
Speed conversions link road, aviation and scientific units. Knots are nautical miles per hour, while Mach depends on the speed of sound in the local medium.
Time
Time conversions use fixed definitions for seconds and days. Months and years are averages here — a calendar month varies from 28 to 31 days.
Data Storage
Data storage conversions mix decimal units (kB = 1,000 bytes) and binary units (KiB = 1,024 bytes). This page uses bits as the base, so 1 byte = 8 bits.
Pressure
Pressure conversions appear in tyres, weather, diving and engineering. The pascal is the SI unit; bar, atm, psi and mmHg are the working units in each field.
Energy
Energy conversions cover nutrition, electricity and heating. The calorie here is the small calorie (4.184 J); the food Calorie (kcal) is 1,000 of them.
Power
Power conversions connect electrical watts with mechanical horsepower. Mechanical and metric horsepower differ by about 1.4%, so check the standard before specifying an engine.
Fuel Economy
Fuel economy is the only category with inverse units: litres per 100 km falls as efficiency rises, while miles per gallon rises. The conversion is therefore a division, not a multiplication.
How to choose the right page
Open the category that matches the quantity you are measuring, then pick the starting unit. If you need the opposite direction, every page has a swap link. The search engines index each pair separately, so you can also search for the exact conversion, for example "cm to inches" or "kg to lbs".