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Converting US customary units of volume

Sal converts between gallons, quarts, pints, cups, and fluid ounces. Created by Sal Khan.

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Video transcript

So right here we've listed two quantities or two fluid volumes right over here in terms of gallons, 1 gallon and 2 gallons. And what I want to do in this video is try to convert this quantity of fluid, this volume of fluid, I want to convert it into these other units within the US customary system. So I encourage you to pause the video and first try to do the 1 gallon. Try to convert it into quarts, pints, cups, and fluid ounces. Well, 1 gallon is equal to 4 quarts. So we can just multiply by 4. 1 quart is equal to 2 pints, so we can multiply this by 2. So 4 quarts, each of them are 2 pints. 4 times 2 gets us to 8 pints. Each pint is equal to 2 cups, so we have 8 pints. Each of them are equal to 2 cups. We're going to have 16 cups. And then finally, if we're converting from a cup to a fluid ounce, each cup is 8 fluid ounces. So if we have 16 cups, it's going to be 16 times 8. 8 times 8 is 64, and it's going to be twice that. That's going to be 128 fluid ounces. Now, let's do the same thing with 2 gallons. Try to convert that into quarts, pints, cups, and fluid ounces. And I encourage you to pause the video and try it on your own first. Well, same idea. 1 gallon is equivalent to 4 quarts. So 2 gallons are going to be 2 times 4 quarts, or 8 quarts. quart is 2 pints. So if we want to go from quarts to pints, we'd want to multiply by 2. So this is going to be 16 pints. And then each pint is 2 cups. So multiplying 16 of them, then that's going to be 32 cups. And then finally, each cup is 8 ounces. 32 times 8 is going to be? Let's see, it's going to be 256. And notice something here. When we went from 1 gallon to 2 gallons, we essentially increased the quantity of gallons by 2, or we multiplied by 2. And you see that across the board here as it's going from 4 quarts to 8 quarts. This is going from 8 pints to 16 pints. This is going from 16 cups to 32 cups, going from 128 fluid ounces to 256. When you increase the volume in gallons by a factor of 2, you're, of course, going to increase the volume in any unit you measure it in by a factor of 2.