Volume

[MrArapaima]

How to calculate an Octagon shape tank? height is 18" and I guess L & W is 6 ". it's about 2 " per side of the octagon

[Mr.Bass]

Assuming that you have an even sided octagon:

Area of Octagon (A) = 4.828(a*a), where a = length of each side of the octagon

Volume of Octagon = Area (A) * Height (H)

So: Volume = 4.828(a*a)*H or 4.828(2"*2")*18" = 347.6 cu in

Since this is an aquarium site, I'll further assume you are looking for how much water the Oct will hold:

1 gallon = 231 cu in

So: Gallons = 347.6 cu in * 1g/231 cu in = 1.5 gallons (5.7 liters)

[RTR]

Except that the original poster is in London, therefore need the volume in Imperial gallons. The conversion factor for imperial gallons is 277.42 cubic inches per Imperial gallon.

[Mr.Bass]

Good eye there RTR! I notice the poster was from the UK, which is why I threw in the litre at the end. Shoulda' went back & posted the other version of gallons:D

[RTR]

Someday we'll all use litres, but despite all those years in the lab, I still think tanks in US gallons.