Unit Conversion Calculators

Convert any common measurement between units. Pick a category, enter a value, and see the factor, working, and every unit in that family.

Convert between Celsius, Fahrenheit, Kelvin and Rankine. Absolute zero is blocked; all four scales update together.

Convert centimetres to inches and back using the exact 2.54 factor, with working and a nearby-values table.

Convert height between centimetres and feet-and-inches. Bidirectional, with a mixed feet + inches readout.

Convert acres to square feet and back. One acre equals exactly 43,560 square feet.

Convert cubic feet to cubic yards and back. One cubic yard equals exactly 27 cubic feet.

Convert hours to days and back using 24 hours per day, with decimal and mixed readouts.

Convert hours to minutes and back. One hour equals 60 minutes.

Find the area of common shapes, then convert the result across square units. Geometry shape pages own deeper per-shape tools.

Convert a distance between length units (miles, kilometres, feet, metres). For distance between two coordinate points, use the geometry Dist

Convert between decimal (GB) and binary (GiB) storage units. See why a 500 GB drive shows as about 465 GiB.

Convert recipe volumes, or convert volume to weight by ingredient. A cup of flour and a cup of sugar do not weigh the same.

Convert density between kg/m³, g/cm³, lb/ft³ and related units. For mass from density and volume, use the physics Mass Calculator.

Convert energy between joules, calories, kilowatt-hours and BTU. For kinetic energy or work from equations, use the physics solvers.

Convert force between newtons, kilogram-force, pound-force and dyne. For F = ma, use the physics Acceleration Calculator.

Convert acceleration between m/s², ft/s², g and gal. For solving kinematics, use the physics Acceleration Calculator.

Convert angles between degrees, radians, gradians, turns and arcminutes. Radians can be shown relative to π.

Estimate download time from file size and connection speed. Network rates use bits; files use bytes (factor of 8).

Spell out numbers in English words, with currency and ordinal formats for forms and cheques.

Convert GPS coordinates between decimal degrees and degrees-minutes-seconds, either direction.

Convert mass and weight across metric, avoirdupois and troy. Troy and avoirdupois ounces differ; the system selector keeps them apart.

Convert between m/s, km/h, mph, ft/s and knots. Bidirectional with the factor and nearby speeds shown.

Convert pascals, bar, atmospheres, psi, mmHg and torr. Useful for tyres, weather and lab work.

Convert watts, kilowatts and horsepower. Mechanical and metric horsepower are listed separately because they differ.

Convert momentum units such as kg·m/s and lb·ft/s. This is a unit converter; the impulse equation lives on the physics pages.

Convert between SI prefixes from quecto to quetta for any base unit. The maths is a power of ten; the base is only a label.

Convert numbers to Roman numerals and Roman numerals to numbers, with validity checks, vinculum for large values, and a date mode.

Convert US, UK and EU shoe sizes via foot length in centimetres. Charts are approximate; brands and width still matter for fit.

Convert minutes to decimal hours and back for payroll and timesheets. Thirty minutes is 0.5 hours.

Convert kilograms to pounds and back. One kilogram is about 2.2046 pounds. Also useful alongside stone for UK body weight.

Convert metres to feet and back. One metre is about 3.2808 feet. Nearby values and a clear factor panel are included.

Convert square feet to square meters (and back). One square foot is 0.09290304 m².

Find the volume of common solids, then convert the result across cubic units. Geometry solid pages own deeper per-shape solvers.

Convert Celsius to Fahrenheit with the formula shown and the reverse direction one click away.

Convert Celsius to Kelvin by adding 273.15, with the reverse direction and absolute-zero blocking built in.

Convert Celsius to Rankine by routing through Kelvin and scaling by 9/5, with the reverse direction included.

Convert Fahrenheit to Kelvin with the Celsius mid-step shown, plus the reverse direction.

Convert Fahrenheit to Rankine by adding 459.67, the simplest pair in the temperature set, plus the reverse.

Convert Kelvin to Rankine by multiplying by 9/5, the pure-factor pair among the absolute scales, plus the reverse.

A general-purpose temperature calculator covering Celsius, Fahrenheit, Kelvin and Rankine in any direction.

Convert a height in centimetres into feet and inches, with the reverse direction on a second tab.

Convert feet and inches to cm, or reverse height to cm back into feet and inches.

Convert pounds to kilograms and back. One pound is exactly 0.45359237 kilograms.

Convert square metres to square feet and back for floor plans and listings. One square metre is about 10.7639 ft².

Spell a number in words or an amount in words, with currency and ordinal formats on other tabs.

Convert a calendar date into Roman numerals, in the day-month-year format used on monuments and film credits.

Convert avoirdupois weight units, the everyday pounds-and-ounces system used for body weight and groceries.

Convert troy weight units used for precious metals and gemstones, where a troy ounce differs from an avoirdupois ounce.