# computing water volume
**URL:** https://boards.straightdope.com/t/computing-water-volume/705792
**Category:** Factual Questions
**Created:** [November 28, 2014, 12:22am UTC](https://boards.straightdope.com/t/computing-water-volume/705792 "2014-11-28T00:22:47Z")
**Posts on this page:** 7
**Page:** 1
### Author:  [@cedman](https://boards.straightdope.com/u/cedman)
#### Post date: [November 28, 2014, 12:22am UTC](https://boards.straightdope.com/t/computing-water-volume/705792/1 "2014-11-28T00:22:47Z")
I have a well and only basic math skills.
I need to find out how much water in gallons can be held in a well casing of 24 inches diameter and a depth of 15 feet.
Can any of you math geniuses help me out?
Thanks!
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### Author:  [@johnpost](https://boards.straightdope.com/u/johnpost)
#### Post date: [November 28, 2014, 12:38am UTC](https://boards.straightdope.com/t/computing-water-volume/705792/2 "2014-11-28T00:38:44Z")
well that is a cylinder.
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### Author:  [@boffking](https://boards.straightdope.com/u/boffking)
#### Post date: [November 28, 2014, 12:43am UTC](https://boards.straightdope.com/t/computing-water-volume/705792/3 "2014-11-28T00:43:24Z")
Assuming your well is a cylinder you have 47.1 cubic feet of water. This is about 352 gallons.
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### Author:  [@Giles](https://boards.straightdope.com/u/Giles)
#### Post date: [November 28, 2014, 12:59am UTC](https://boards.straightdope.com/t/computing-water-volume/705792/4 "2014-11-28T00:59:51Z")
> [@boffking](#):
>
> … This is about 352 gallons.
352 U.S. liquid gallons, which is about 293 Imperial gallons.
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### Author:  [@jtur88](https://boards.straightdope.com/u/jtur88)
#### Post date: [November 28, 2014, 1:17am UTC](https://boards.straightdope.com/t/computing-water-volume/705792/5 "2014-11-28T01:17:32Z")
Convert to metric, do it quickly in your head, convert back again. That’s why metric was invented. One liter of water weighs one kilogram and occupies 1,000 cubic centimeters…
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### Author:  [@kaylasdad99](https://boards.straightdope.com/u/kaylasdad99)
#### Post date: [November 28, 2014, 1:21am UTC](https://boards.straightdope.com/t/computing-water-volume/705792/6 "2014-11-28T01:21:02Z")
Convert your linear measurements to metric (2.54 cm/in)
24 in X 2.54cm/in = 60.96cm diameter (30.48cm radius)
15 ft X 12 in/ft X 2.54 cm/in = 457.2cm depth
Volume of a cylinder is equal to depth times area of the cross section.
Area of a circle = pi X the square of the radius, so (10.78cm)[sup]2[/sup] X pi = 929.0304cm[sup]2[/sup] X 3.14159 = 2919cm[sup]2[/sup]
2919cm[sup]2[/sup] X 457.2cm = 1334400cm[sup]3[/sup]
That’s how many cc of water fits when the well is full to the brim. To convert to liters, divide by 1000 for 1334.4 liters
There are 1.056 quarts in a liter, so multiply by 1.056 to get the number of quarts 1334.4 X 1.056 = 1408 quarts (roughly. I’m fudging the numbers to achieve an even number of gallons).
There are four quarts in a gallon, so divide that by four to get the number of gallons 1408/4 = 352 gallons.
Or, you could just stay in imperial measurements and use the fact that there are 231 cubic inches in a gallon of water (standard temperature and pressure).
15 feet = 180 inches =\> 180 x 12[sup]2[/sup] X pi / 231 = 352 gallons
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### Author:  [@Giles](https://boards.straightdope.com/u/Giles)
#### Post date: [November 28, 2014, 1:24am UTC](https://boards.straightdope.com/t/computing-water-volume/705792/7 "2014-11-28T01:24:24Z")
> [@kaylasdad99](#):
>
> Or, you could just stay in imperial measurements and use the fact that there are 231 cubic inches in a gallon of water (standard temperature and pressure).
Nitpick: there are 231 cubic inches in a gallon of water using U.S. customary measurements, not imperial!