Originally Posted by
MantaLady Just for clarity, to work out the units in any bottle of alcohol or drink it is a pretty simple and universal formula. A bottle of vodka usually has around 40% ABV, if you times that by the ml in the bottle and divide by 1000 you get the units.
There's a lot of vodka which is around 37% ABV and some stronger than 40% too. This would account for some of difference in units.