found this which is quite handy for me :D
http://www.petfish.net/calculate.htmDon't forget to take off glass thickness :D
sweet link that can help with alot especially building your own tank like i plan on doing. when i get the room i plan on building a 600 + gall tank and that link will help to determine the exact size of the compleat tank
This link is handier than I thought my tank is actually 158 gallons (599L) and weighs 1316 Pounds (599kg) when full dummy