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Math in Daily Life
Cooking by Numbers

Bureau International des Poids et Mesures
This organization's site (available in French or English) features metric conversion charts, standards information, and more.

Metric Conversion Card
Use this easy chart to convert inches to centimeters, pounds to kilograms, Fahrenheit to Celsius, and more.

Metric Conversions
Learn how metric and English symbols are used to measure and express mass, length, volume and temperature.

Meters and Liters: Converting to the Metric System of Measurements

Most of the world uses a standard system of measurements called the metric system. This system is based on a unit of measurement called the meter, which gets its name from the Greek word metron, "a measure." One meter is equal to 1 ten-millionth of the distance from the equator to the North Pole. It's a standard for measuring length that is derived from the planet we live on.


1 inch = 2.5 cm
1 foot = 30 cm
1 yard = 0.9 m
1 mile = 1.6 km
1 pound = 0.45 kg
1 teaspoon = 5 ml
1 cup = 0.24 l
32 degrees F = 0 degrees C
(freezing point)

The metric system has been around for 300 years. France was instrumental in its creation and in 1795 was the first country to adopt it (though in the early 1800s, the emperor Napoleon briefly set it aside in favor of the old system of measurement). The United States remains one of the few countries that has not yet adopted the metric system as the standard for measurement.

Converting to metric values

Remember that mouth-watering chocolate chip cookie recipe? What if you wanted to send it to a friend in Portugal? You could send him the recipe with the measurements given in cups and teaspoons and hope it worked out for the best. Or you could convert the recipe to metric values, guaranteeing that the cookies would taste as delicious in Portugal as in the U.S.

To convert from cups to the appropriate metric measurement, liters, you need to know how many cups are in a liter. The table on this page shows some common conversion values. You can see that 1 cup is equal to 0.24 liters. To convert your 1 cup of flour to liters, you'd multiply 1 by 0.24. The chocolate chip cookie recipe calls for 0.24 liters of flour.

What about sugar? In the original recipe, you need 1/3 of a cup of sugar. To make the conversion easier, convert the fraction 1/3 to a decimal: 0.33. Now multiply 0.33 by 0.24. Your friend will need 0.08 liters of sugar to make your cookie recipe.

Making the transition to metric measures

Although Thomas Jefferson and John Quincy Adams once promoted its ease and efficiency, the metric system has been slow to gain a hold in the U.S. That may change, however. The U.S. government still hopes to gain acceptance of the metric system gradually by enlisting the support of business and industry. Most businesses that sell products abroad use metric measurements, sometimes in addition to inches or ounces. In 1994, Congress passed a law requiring that packaging for consumer products include both traditional and metric measurements.

Even if you live in the U.S., you're using the metric system—probably without realizing it. The computer you're using might have several megabytes of memory and a few gigabytes of storage. Mega- and giga- are prefixes used in the metric system. Mega- stands for "one million," so a megabyte is a million bytes. Giga- stands for "one billion." If computing continues at the rate it's been going, we may soon be talking about petabytes—one million billion bytes.

[Back to "Cooking By Numbers"] [Next Topic: "The Universal Language"]

 "Math in Daily Life" is inspired by programs from For All Practical Purposes.

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