In the metric system, grams are used to measure light loads and kilograms are used to measure heavier loads. There are 1000 grams in one kilogram. This means that converting grams to kilograms is easy: just divide the number of grams by 1000.
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Method 1 of 2: Transforming by Calculation
Step 1. Write down the gram
Label it "grams" or "g". If you're using a calculator, just enter the numbers.
In this section, we will follow the steps with sample problems to make the calculations easier. Suppose we want to convert 20,000 grams into kilograms. To begin, we will write " 20,000 grams" on our paper.
Step 2. Divide by 1000
One kilogram is equal to one thousand grams. This means that to get kilograms from grams, you just need to divide the number of grams by 1,000.
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In our example, we'll get kilograms by dividing 20,000 grams by 1,000.
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20.000/1.000 =
Step 20.
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Step 3. Label your answer
Don't forget this step! Labeling the correct units in your answer is very important. If you're doing this conversion for schoolwork, you could lose points if you don't include unit labels. If you do the conversion for other purposes, other people may assume the wrong units.
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In our problem, we will label our answer with "kilograms" like this:
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- 20 kilograms.
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Step 4. To return to grams, multiply by 1,000
As discussed above, one kilogram is equal to a thousand grams. This means that if you want to return the units to grams from kilograms, all you have to do is multiply the kilogram by 1,000. Since multiplication is essentially the "reverse" operation of division, it "undoes" the division and gives the result in grams.
- To return 20 kilograms to grams, we just need to multiply it by 1,000 (don't forget to label your answer again):
- 20 kilograms × 1000 = 20,000 grams
Method 2 of 2: Changing by Shifting the Decimal Point
Step 1. Start with your gram size
Believe it or not, you can convert grams and kilograms without doing any calculations. This can be done because the metric system is a measurement system with a base of 10. In other words, metric units are always multiples of 10 for each unit difference; there are 10 millimeters in a centimeter, 100 centimeters in a meter, 1,000 meters in a kilometer, and so on.
In this section, let's convert 37 grams to kilograms. We'll start in the same way as in the section above, i.e. writing " 37 grams" on our paper.
Step 2. Shift the decimal point three places to the left
Now, find the decimal point in your gram. If you're converting whole numbers, usually the decimal point won't be listed, but you can assume the decimal point is to the right of the ones place. Move the decimal point three places to the left. Every time you pass a number, it counts as one place. If you've run out of numbers to skip, keep moving the decimal point while leaving blanks.
- In our example, the decimal point in 37 grams is to the right of the number 7 (37 grams equals 37.0 grams). If we shifted the places one by one, moving the decimal point three places to the left would look like this:
- 37, 0
- 3, 70
- , 370
- , _370 - note that we can leave a blank when we run out of numbers.
Step 3. Add zeros in the blanks
You can't leave blank spaces in your answer, so fill in the blanks with zeros. You can also put a zero to the left of the decimal place if there's no number there, but this is optional - it just depends on how you write your answer.
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In our example, we have one blank space between the decimal point and the number 3, so we'll fill it with zeros like this:
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- , 037
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- By adding the proper label (adding an extra zero to the left of the decimal point for writing purposes), we get our final answer:
- 0.037 kilograms
Step 4. To return to grams, shift the decimal places again
When you have kilograms, moving the decimal place three places to the right will give you grams. Fill in the blanks with zeros as usual.
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In our example, we can shift the decimal place three places to the right like this:
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- 0, 037
- 00, 37
- 003, 7
- 0037, - the zeros on the left are no longer important, so we can rewrite this number as 37 grams.
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Tips
- The kilogram is the base unit of the International System of Units (SI) for mass. Gram is a smaller unit of mass in the metric system and the International System of Units. Gram was originally defined as the mass of one cubic centimeter (cm³) of 4°C of water.
- In the metric system, the prefix in the unit indicates magnitude. "Kilo" means that a unit has any thousand (1,000) units behind it (units without a prefix). For example, if you have one kilowatt, you have 1000 watts; if you have one kilogram, you have 1000 grams; if you have 100 kilometers, you have 100,000 meters (and so on).
