32 Calculators
Unit Conversions
Exact conversions for weight, volume, length, temperature, pressure, torque, data size and speed, using NIST-defined factors.
These converters change a measurement from one unit to another: weight, kitchen volume, length, area, temperature, pressure, torque, data size and speed. Each one multiplies by a factor fixed by definition, not by a rounded figure copied from a chart. The pound is exactly 0.45359237 kilograms and the inch exactly 2.54 centimetres under the 1959 international yard and pound agreement, and the US gallon is exactly 231 cubic inches. Every other customary unit on these pages is built from those numbers.
The arithmetic runs in 34-digit decimals, so converting a value and converting it back returns what you typed. Results are rounded only for display, and each page says how many places it shows and why. Where a word means more than one thing, the page says which one it uses: a "cup" here is the US customary cup of 236.5882365 millilitres, and the 240 millilitre cup printed on Nutrition Facts labels is shown separately. A "ton" is always named as a short ton, a long ton or a metric tonne.
Kitchen conversions between volume and weight need a density, and a density is a property of the ingredient, not of the units. Those pages use water, whose density is published by the international metrology bodies, unless they cite a primary measurement for the ingredient itself.
Start here
- A recipe gives weights and I only have measuring cups.
- For water and water-like liquids, the ml to grams converter gives the weight of a volume directly. For a dry ingredient, use the grams to teaspoons converter and pick the ingredient: it uses the cup weight USDA FoodData Central publishes, because a cup of flour and a cup of sugar weigh very different amounts.ml to Grams Converter (water and common ingredients)Grams to Teaspoons Converter (and tablespoons and cups)
- My scale shows 2.3 lb. How many pounds and ounces is that?
- Enter 2.3 in the pounds to ounces converter. It gives 36.8 ounces in total and 2 lb 4.8 oz as a scale would print it.Pounds to Ounces Converter (lb to oz and oz to lb)
- Why does my new drive show less space than the box says?
- Put the advertised size into the data size converter and read the binary figure beside it. The bytes are all there; the two numbers count them in different units.Data Size Converter (KB, MB, GB, TB and KiB, MiB, GiB)
How these calculators fit together
Weight
The pounds to ounces converter works in both directions and also splits a decimal weight into whole pounds and ounces, which is how a kitchen or postal scale reads it. The grams to ounces, grams to pounds and kg to lbs converters cover the metric side of the same chain; the grams to ounces page also shows the troy ounce used for precious metals. The stones to pounds converter gives a weight as whole stone and pounds, the way UK and Irish scales show it.
Pounds to Ounces Converter (lb to oz and oz to lb)Grams to Ounces Converter (g to oz and oz to g)Grams to Pounds Converter (g to lb and lb to g)Kg to Lbs Converter (kilograms to pounds and back)Stones to Pounds Converter (st to lb and lb to st)
Kitchen volume
Cups, fluid ounces, tablespoons and teaspoons are fixed fractions of the US gallon: 16 cups, 128 fluid ounces, 256 tablespoons. These converters move between them and millilitres, and say which cup they use. The gallons, quarts, pints and cups converter handles the bigger steps, four quarts to the gallon and two pints to the quart.
Cups to Ounces Converter (US cups and fluid ounces)Ounces to ml Converter (US fluid ounces and millilitres)Tablespoon and Teaspoon to ml Converterml to Cups Converter (millilitres to US cups)Quarts in a Gallon: Gallons, Quarts, Pints and Cups Converter
Volume to weight
Turning millilitres or cups into grams or pounds needs a density. These pages default to water, using the international CIPM formula for its density, and let you set the water temperature where it matters. They also offer common ingredients whose cup weights are published by USDA FoodData Central, and accept a density you type for anything else. Every result shows the density used and where it comes from.
ml to Grams Converter (water and common ingredients)Grams to Teaspoons Converter (and tablespoons and cups)Water Weight Calculator (gallons, quarts and cups to pounds)
Metric and lab volume
Centilitres, decilitres, millilitres and litres differ by powers of ten, and a cubic centimetre is exactly a millilitre. These converters cover drink labels, European recipes, pipette volumes in microlitres and engine sizes in cc and cubic inches.
cl to Liters Converter (centiliters, milliliters, deciliters)cc to ml Converter (cubic centimetres, microlitres, millilitres)
Rain and snow
The rain to snow calculator scales a depth of rain to fresh snow, or snow back to its liquid equivalent, at a snow-to-liquid ratio you set. It starts at the 10:1 rule of thumb the National Weather Service describes, and says plainly that real ratios vary from storm to storm.
Length and height
Inches to centimetres, kilometres to miles, and height in centimetres to feet and inches. The height converter rounds the inches to one place and carries a remainder that rounds up to twelve into the next foot.
Inches to cm Converter (in to cm and cm to in)Km to Miles Converter (kilometres to miles and back)Cm to Feet and Inches Converter for Height
More lengths, areas and small units
The metric length converter moves between millimetres, centimetres, decimetres, metres and kilometres. Feet, yards and miles have their own page, and metres to miles adds feet and yards. The mm to inches and feet to inches converters give the nearest ruler fraction of an inch as well as the decimal. Pixels to inches asks for the pixel density rather than assuming one. Area units run from square inches to acres and hectares, and the angstrom converter covers picometres to micrometres.
Cm to Meters Converter (mm, cm, dm, m and km)Feet to Miles Converter (feet, yards and miles)Meters to Miles Converter (and Feet and Yards)Mm to Inches Converter (and mm to Feet)Feet to Inches Converter (with Inch Fractions)Pixels to Inches Converter (at Any PPI or DPI)Square Feet to Square Yards Converter (and Other Area Units)Angstrom to Nanometers Converter (Å, nm, µm and m)
Temperature, pressure and torque
Temperature is not a ratio scale: zero degrees Celsius is 32 degrees Fahrenheit, so it is converted by an offset as well as a factor. Pressure covers psi, bar, kilopascals, atmospheres and millimetres of mercury. Torque covers newton metres, foot-pounds and inch-pounds.
Temperature Converter (Celsius, Fahrenheit and Kelvin)Pressure Converter (psi, bar, kPa, atm and mmHg)Torque Converter (Nm to ft-lb, in-lb and Back)
Data size and speed
A kilobyte is 1,000 bytes to a drive maker and 1,024 bytes to most operating systems. The data size converter shows both, under their separate names, so a 1 TB drive reading about 931 GiB stops looking like missing space. The speed converter handles knots, miles per hour, kilometres per hour and metres per second.
Data Size Converter (KB, MB, GB, TB and KiB, MiB, GiB)Knots to mph Converter (and km/h, m/s)
What these tools leave out
- Only US customary volume is covered. Imperial (UK) pints, gallons and fluid ounces are larger and use different factors.
- A volume to weight conversion is only as good as the density behind it. These pages state the density they use and where it comes from.
- Displayed results are rounded. For work that needs more places, use the full figure in the reference table download.
All Calculators
Converts very small lengths between picometres, angstroms, nanometres, micrometres, millimetres and metres in any direction, and writes the metre value in scientific notation.
Converts between cubic centimetres, millilitres, microlitres, litres, cubic inches and US fluid ounces in any direction, with 1 cc equal to exactly 1 mL.
Converts between centiliters, milliliters, deciliters, liters, US fluid ounces and US gallons in any direction, using the exact SI prefixes and the 231 cubic inch US gallon.
Converts a height in centimetres to feet and inches, or feet and inches to centimetres, and gives it as total inches, decimal feet and metres.
Converts a length between millimetres, centimetres, decimetres, metres and kilometres in any direction, showing all five units at once.
Converts US cups to US fluid ounces and back at exactly 8 fluid ounces to the cup, with the same volume in millilitres, tablespoons, 240 mL label cups and as a weight of water.
Converts an amount of data between bits, bytes, decimal units (kB to TB) and binary units (KiB to TiB), and works out how long it takes to transfer at a given speed.
Converts feet and inches to total inches and back, writes the inches as a fraction to the nearest sixteenth or finer, and gives the length in centimetres.
Converts a distance between feet, yards and miles in any direction at exactly 5,280 feet and 1,760 yards to the mile, and gives it in metres.
Converts grams to avoirdupois ounces and back at exactly 28.349523125 g to the ounce, with pounds, kilograms, troy ounces and the 28 g nutrition label ounce alongside.
Converts grams to pounds and pounds to grams at exactly 453.59237 g to the pound, with pounds and ounces, kilograms, ounces and milligrams alongside.
Converts grams to US teaspoons, tablespoons or cups and back through a stated density, using water at 20 °C, a USDA FoodData Central measure for 15 common ingredients, or a density the reader enters.
Converts inches to centimetres and centimetres to inches at exactly 2.54 cm to the inch, splits the length into feet and inches, and gives it in millimetres and metres.
Converts kilograms to pounds and pounds to kilograms with the exact 1959 pound of 0.45359237 kg, and splits the weight into pounds and ounces and into stone and pounds.
Converts kilometres to miles and miles to kilometres at exactly 1.609344 km to the mile, and gives the distance in metres, feet and nautical miles.
Converts a speed between knots, miles per hour, kilometres per hour, metres per second and feet per second in any direction.
Converts a distance between metres, feet, yards and miles in any direction, and gives the length in feet and inches.
Converts millilitres to US customary cups and back at exactly 236.5882365 mL to the cup, with the 240 mL label cup, fluid ounces and tablespoons alongside.
Converts millilitres to grams and back through a stated density, using the CIPM formula for water at a chosen temperature, a USDA FoodData Central measure for 15 ingredients, or a density the reader enters.
Converts millimetres to inches or feet and back, and gives the nearest ruler fraction of an inch along with feet and inches and centimetres.
Converts US fluid ounces to millilitres and back at exactly 29.5735295625 mL to the fluid ounce, with the 30 mL label fluid ounce, cups, tablespoons and litres alongside.
Converts a pixel count to inches, centimetres and millimetres, or a physical size to pixels, at a pixel density the user sets.
Converts pounds to ounces and ounces to pounds at exactly 16 ounces to the pound, splits a decimal weight into pounds and ounces, and gives the weight in kilograms and grams.
Converts a pressure between psi, bar, millibar, pascals, kilopascals, megapascals, atmospheres, mmHg, torr and inHg, and shows the gauge or absolute equivalent at one standard atmosphere.
Converts between US gallons, quarts, pints, cups, fluid ounces and litres in any direction, using the 231 cubic inch US gallon and its exact fractions.
Converts a depth of rain or liquid water to fresh snow depth, and snow to its liquid equivalent, at a snow-to-liquid ratio the reader sets, defaulting to the 10:1 rule of thumb.
Converts an area between square inches, square feet, square yards, square metres, acres, hectares and square miles in any direction.
Converts stone to pounds and pounds to stone at exactly 14 pounds to the stone, with the stone and pounds split, decimal stone and kilograms.
Converts between US teaspoons, US tablespoons, millilitres, fluid ounces and the 5 mL and 15 mL label spoons in any direction, using the exact US customary spoon sizes.
Converts a temperature between Celsius, Fahrenheit and kelvin in any direction, and converts the same number as a temperature change.
Converts a torque between newton metres, foot-pounds, inch-pounds and kilogram-force metres in any direction, using exact pound-force and foot definitions.
Works out the weight of a volume of water at a chosen temperature, or the volume of a weight, in US customary and metric units, and does the same for 15 USDA ingredients or a density the reader enters.