Metric steps and imperial ratios
Metres, kilograms and litres mostly scale by powers of ten. Inches, pounds and gallons rely on other relationships, so the measurement family must be identified before the value is multiplied.
Free tools
Conversions
Conversion tools solve cases where a correct value becomes hard to use because it is written in the wrong unit. A US recipe, a DIY plan, tyre pressure, weather temperature, travel speed or file size each follows its own convention. Converting inches to centimetres is unlike changing gigabytes to megabytes, since the factors do not always come from the same system. Length, weight, volume, area, temperature, speed, pressure and data-storage pages help move from one notation to another without mixing prefixes, imperial units and physical quantities.
Temperature requires an offset
Celsius, Fahrenheit and Kelvin are not proportional scales. Their zero points differ, which means the formula needs both a factor and an added or subtracted constant.
Area and volume amplify unit mistakes
Changing centimetres into metres is linear for a length. Square units and cubic units grow in two or three dimensions, which explains why the wrong factor can produce a huge error.
Pressure and speed in context
Bar, psi, pascal, kilometres per hour and miles per hour appear in tyres, compressors, weather reports, sport and travel. The converter keeps the measured quantity visible so an equivalent is not applied to the wrong use.
Digital storage prefixes
Files, disks and network rates may be described in bits, bytes, KB, MB, GB or GiB. Data conversions separate decimal and binary multiples when capacity needs to be read accurately.
Frequently asked questions
Why is a Fahrenheit conversion not just a multiplication?
Fahrenheit and Celsius start from different zero points. The formula has to adjust the offset as well as the scale, unlike a distance conversion.
What causes mistakes when converting square metres?
Area has two dimensions. One metre equals 100 centimetres, but one square metre equals 10,000 square centimetres because both sides are converted.
Why do storage devices show different capacities after conversion?
Manufacturers often use decimal gigabytes, while operating systems may display binary gibibytes. The different base explains the apparent loss.
Tools to explore
Unit Converter
Convert measurements between metric and imperial systems: length, mass, volume, temperature, area and speed.
Length Converter
Convert meters, centimeters, millimeters, kilometers, inches, feet, yards and miles with visible factors.
Weight / Mass Converter
Convert kilograms, grams, milligrams, tonnes, pounds, ounces and stones with visible factors.
Volume Converter
Convert liters, milliliters, centiliters, cubic meters, US gallons, imperial gallons, cups, pints and fluid ounces with clear factors.
Area Converter
Convert square meters, square centimeters, square millimeters, hectares, acres, square feet and square inches with clear factors.
Temperature Converter
Convert Celsius, Fahrenheit, Kelvin, Rankine and Réaumur with formulas and practical references.
Speed Converter
Convert km/h, m/s, mph, knots, ft/s and Mach with formulas and practical references.
Pressure Converter
Convert pascals, bars, PSI, atmospheres, mmHg, kPa and MPa with formulas and practical references.
Data Storage Converter
Convert bits, bytes, KB, MB, GB, TB, KiB, MiB, GiB and TiB with decimal and binary references.
Kitchen Mass-Volume Converter
Convert grams, milliliters, cups, spoons, ounces and pounds by ingredient with density, tables and recipe examples.
Energy Converter
Convert kWh, joules, Wh, MJ, kcal, BTU, thermies and electronvolts with a table, formulas, indicative cost and practical references.
Shoe Size Converter
Convert EU, UK, US men, US women, centimeters and inches with a table, foot measurement guide, fit advice and purchase currency.
Clothing Size Converter
Convert FR, EU, US, UK, international sizes and body measurements with a table, fit guide, cm measurements and purchase currency.