Math help.

How do I figure out how much water is in my tank? Its a half moon shape.
Back width is 31"
Depth is 16"
Height is 23"
Just fyi I mean half a circle. Not bow front.

I was told it was 30 gallon but in my excitment to get started we just fiilled it and added rock and sand. Ended up putting in about 35 to 40 gallons. I think. Like I said I was excited.:

 

volume of a cylinder is (pi)(radius^2)(height). So just do that then divide it by 2

Edit: That will give you cubic inches. 1 cubic inch=0.00432900433 gallons

 

to my calculations it would be about 8488.55 cubic inches and that would come out to be about 36.74 gallons so your more accurate lol

 

Right.

 

or you can try the 3reef calculators

3reef.com - Forums for coral reef aquariums, salt water fish, corals, inverts, protein skimmers, aquarium lighting and more - Calculators

 

That too lol

Edit: Actually I don't think it does volume for odd shaped tanks