Hi everyone, looking to calculate my current boards volume as i'm looking to buy a similar board but it has slightly different dims and i can't actually go and see the board as its in a different part of the country!

Obviously cubic volume will be Length x Width x Thickness, but i don't see how this can be accurate as surfboards aren't rectangular

Current dims 5'5 x 19 1/2 x 2 3/4

Board i'm looking at 5'7 x 19 x 2 1/8 (-1/2 inch at widest point, - 5/8 thickness and + 2 inches in length)

Both boards are low rocker, single all the way through grovel type boards. So looking at the dim's i don't see there being much difference in volume, what do you think?