A quantity measured in kilocalories (kcal) is converted to calories (cal) by multiplying it by 1,000. The prefix "kilo-" comes from the metric system and means "one thousand," even though calories are not themselves metric units.
- Check that the quantity is given in kilocalories
Because the kilocalorie is used to measure the caloric content of food, it is more commonly referred to as the food calorie or the large calorie. Outside of nutrition, the calorie is much more common, so it is important to make sure the correct units are used.
- Multiply the original quantity by 1,000
One kilocalorie is equivalent to 1,000 calories, so multiplying by 1,000 is the only step required to convert kilocalories to calories. To accomplish this, locate the decimal point in the original quantity and move the decimal point three places to the right, adding zeros as necessary.
- Rewrite the converted quantity in scientific notation, if necessary
In scientific writing, numeric quantities with more than two digits to the left of the decimal point are usually expressed in scientific notation. If necessary, write the converted quantity in scientific notation by dividing by a power of 10 such that the new quantity is between 1 and 100. Then, write the converted quantity as the new quantity times the power of 10. For instance, 3,059 calories is written as 3.059 x 10^3 calories in scientific notation.