Measurement Conversions for General Use

This free measurement converter switches between US customary units and metric units in eight everyday categories: weight (mass), volume, temperature, length, distance, food energy, area and fuel consumption. It is built for the conversions people actually need at home: following a recipe written in cups when your kitchen scale reads grams, reading a nutrition label in kilojoules, checking a European car's fuel economy in miles per gallon, or working out how many square meters a room is before ordering flooring.

How to Use the Measurement Converter

Choose a category from the Select a Category menu, then type a number into any field. Every other field in that category updates as you type. There is no "from" or "to" box and no Convert button: whichever field you type in becomes the starting value, so you can go from cups to milliliters or from milliliters to cups with the same set of fields. Clearing a field clears the rest of its group, ready for the next value.

Area works a little differently because an area comes from two measurements. Pick the unit your measurements are in, enter the length and width, and the table shows the area in square meters, square yards, square feet, square inches and square centimeters.

Units Included in Each Category

Cooking and Kitchen Conversions

Most recipe conversions are volume conversions: cups, tablespoons and teaspoons in American recipes against milliliters and liters everywhere else. The US kitchen measures are tied to each other by simple ratios. There are 3 teaspoons in a tablespoon, 2 tablespoons in a fluid ounce, 8 fluid ounces in a cup, 2 cups in a pint, 2 pints in a quart and 4 quarts in a gallon.

Which cup does this converter use?

There is more than one "cup". This converter uses the US legal cup of 240 mL, the cup used on US nutrition facts labels. The traditional US customary cup, still common in older American cookbooks, is slightly smaller at about 236.6 mL. The metric cup used in Australia, New Zealand and Canada is 250 mL. For most recipes the difference is too small to matter, but it can add up in baking when a recipe calls for several cups.

Spoons vary too. The Australian tablespoon is 20 mL, a third larger than the US tablespoon of about 14.8 mL, so an Australian recipe's "1 tablespoon" is closer to 4 US teaspoons than 3.

US versus Imperial (UK) units

All volume units in this converter are US units. The British Imperial system shares the names but not the sizes: an Imperial pint is about 568 mL compared with 473 mL for a US pint, and an Imperial gallon is about 4.546 liters compared with 3.785 liters for a US gallon. If an older British recipe asks for a pint of milk, it means roughly 20 per cent more than an American pint.

Can I convert cups to grams?

Not directly. Cups measure volume and grams measure mass, and how much a cup weighs depends on the ingredient. A cup of water weighs about 240 g, but a cup of flour weighs roughly half that and a cup of sugar somewhere in between. To convert a recipe ingredient from cups to grams you need that ingredient's density, or a recipe that already gives weights. Mass conversions such as ounces to grams or pounds to kilograms are exact and need no such information.

Weight Conversions: Ounces, Pounds, Grams and Kilograms

One ounce is 28.35 grams and one pound (16 ounces) is 453.59 grams. Going the other way, one kilogram is 2.205 pounds. These are the avoirdupois ounce and pound used for food and body weight in the United States. The fluid ounce in the volume category is a different unit: it measures volume, not weight, and only for water do the two come out close.

Oven Temperatures: Fahrenheit and Celsius

To convert Fahrenheit to Celsius, subtract 32 and multiply by 5/9. To convert Celsius to Fahrenheit, multiply by 9/5 and add 32. Water freezes at 0 ℃ (32 ℉) and boils at 100 ℃ (212 ℉), and normal body temperature is about 37 ℃ (98.6 ℉). The two scales meet at -40, where -40 ℃ and -40 ℉ are the same temperature.

Recipes written for fan-forced (convection) ovens are usually about 20 ℃ (or 25 ℉) lower than those for conventional ovens. The converter changes the units only, so make that adjustment separately if your oven differs from the one the recipe was written for.

Calories and Kilojoules on Food Labels

The Calorie on a food label (with a capital C) is a kilocalorie, the energy needed to raise the temperature of one kilogram of water by one degree Celsius. Nutrition labels in Australia, New Zealand and the European Union show energy in kilojoules, often alongside Calories. One Calorie is 4.184 kilojoules, so a 2,000 Calorie daily intake is about 8,368 kJ, and 100 kJ is about 24 Calories. Use the food energy category to compare labels from different countries or to follow a calorie target when your local foods list only kilojoules.

Miles and Kilometers for Running and Travel

One mile is exactly 1.609344 kilometers, and one kilometer is about 0.621 miles. Runners often need this for race distances: a 5K is 3.11 miles, a 10K is 6.21 miles, a half marathon (21.1 km) is 13.1 miles and a marathon (42.195 km) is 26.2 miles. It is equally handy for road signs and speed limits when driving abroad.

Fuel Economy: MPG, L/100 km and km/L

Fuel economy is measured in two opposite ways. Miles per gallon (mpg), used in the United States, and kilometers per liter (km/L), used in parts of Asia and Latin America, measure distance per unit of fuel, so a higher number is better. Liters per 100 kilometers (L/100 km), used in Europe, Canada and Australia, measures fuel per unit of distance, so a lower number is better.

Because one is the inverse of the other, the conversion is a division rather than a multiplication: divide 235.2 by the mpg figure to get liters per 100 km. A car rated at 30 mpg uses about 7.84 L/100 km, and one rated at 40 mpg uses about 5.88 L/100 km. The mpg in this converter is based on the US gallon. A UK mpg figure uses the larger Imperial gallon and is about 20 per cent higher for the same car.

Calculating Area in Square Feet and Square Meters

Area is length multiplied by width, and the result is in square units. A room 12 feet by 15 feet is 180 square feet, which is 20 square yards or about 16.72 square meters. One square meter is 10.764 square feet, and one square yard is 9 square feet. Converting area is not the same as converting length: a meter is about 3.28 feet, but a square meter is about 10.76 square feet, because both dimensions are converted. Entering the length and width in their original unit avoids that common mistake, and it is useful for flooring, paint, carpet, tiles, garden beds and real estate listings.

How Accurate Are the Conversions?

The converter uses the exact international definitions: 1 inch is 2.54 centimeters, 1 pound is 0.45359237 kilograms, 1 mile is 1.609344 kilometers, 1 US gallon is 3.785411784 liters and 1 Calorie is 4.184 kilojoules. Every conversion is calculated from these values instead of from rounded factors, so converting a value one way and then back gives the number you started with, apart from display rounding.

Results are rounded to a sensible number of decimal places for each unit, so that small units such as milliliters and grams show whole numbers while large units such as gallons and kilograms keep enough decimals to stay meaningful. A result too small for its usual decimal places is shown to two significant figures instead of as zero, so 0.1 grams appears as 0.0035 ounces. For everyday cooking, travel and home projects, this is more precision than you will need.

Weight, volume, length, distance and fuel consumption cannot be negative, so a negative entry in one of those categories leaves the other fields blank. Temperature is the exception: -40 ℃ converts to -40 ℉ as expected.