Will work if you measure the radius, half way upI use this http://www.online-calculators.co.uk/volume...indervolume.php
Doesn't account for tapered vessels though.
Cheers.
easiest is just weigh it, fill it and weigh it again. depending on your scales accuracy i would just asume water is 1kg/L, but it is actually about 0.9982 at 20DegC