# Thread: Calculating gallons of water in pool...

1. ## Calculating gallons of water in pool...

I need some help calculating the amount of gallons in my pool. All of the pool calculators I have used do not give the option to calculate an L shaped or maybe I just missed it. My pool dimension are 18x46x30x18 with standard 3' shallow end and 8'6" deep end.

2. to calculate the volume of an L shaped pool break it into it's two rectangular areas, calculate each one separately and then add the two volumes obtained together to get your total volume.

The formula for calculating a rectangular pool (there are two in a L shaped pool!) is:
Length x Width x Average Depth x7.5
(Length x Width x Average Depth gives you the volume in cubic feet and there are approx. 7.5 gallons of water in each cubic foot)

To calculate the average depth you can add the deep and shallow ends together in each of your rectangles and divide by 2 if the slope is fairly even throughout. If it is not it will be more accurate to actually take depth measurements every foot or so and average them.

3. Simearl, Welcome to TFP!!

Of course Evan (Waterbear) is right! I just ran the numbers and (assuming that the shallow end is 18 X 30 and from the 'break' to the deep end is 18 X 28 with a constant slope and flat bottomed hopper) get the following:

18 * 30 = 540
540 * 3 = 1620
1620 * 7.5 = 12,150

18 * 28 = 504
504 * 5.5 = 2772
2772 * 7.5 = 20, 790

20,790 + 12,150 = 32,940 so call it 33,000 gal and you should be pretty close.

If the reason for calculating is to add chems, be sure to underdose the pool! These calculations have a good bit of 'slop' in them and it's easier to have to add chems in 2 doses than to overshoot your mark and have to add another chem, or worse - drain some water and refill, to bring the levels back down.

Again, welcome to the forum - we'll be here if you have any more questions

4. Thanks, I wasn't sure how I needed to calculate the gallons. This will help me when calculating the chems.

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