Using a Formula
- Insert the value in pounds you're converting into the blank space below.This will be represented by the "lb" in the formula. You will use this formula to determine the amount of kilograms. One kilogram is equal to 2.2046226218 pounds (from here on this will be shortened to 2.2).
____ lb * 1 kg
lb = ?kg
- Perform the calculation to get the end result in kilograms.You will first divide 1 kg by 2.2 lbs and then multiply that number by the value you in pounds you are trying to convert.
- Example: Say you want to convert 4 pounds into kilograms. You would first divide 1 kg by 2.2 lbs which equals .45. Then multiply .45 by 4 which equals 1.81. Therefore 4 pounds equals 1.81 kilograms.
Calculating in Your Head
- Subtract the first digit of the weight in pounds from the total number and then divide by two.This method is used most frequently by nurses in calculating dosage for a patient since dosage is often in kilograms while the patient's weight is typically in pounds.
- Example: Convert 46 lbs. Subtract 4 from 46 lbs, which equals 42 lbs. Divide 42 by 2, which equals 21 kilograms. (The answer using the formula is 20.87 kilograms, which can be rounded up to 21 kilograms.)
- If you are doing a homework assignment, make sure to show all your work and use the first method.
- Divide the weight in pounds by 2.2. This will only give you the approximate amount in kilograms. Using the formula above and a calculator is the most reliable method if you're looking for a specific answer.
- The methods for calculating the conversion between pounds and kilograms in your head are only approximate.