Hi Netty
This unit business can be damn confusing

there seem to be quite large variations between countries as to what a unit of alcohol is.
For our personal tracking on the SM we don't really need to know exactly how much a unit is- we only use units as way of charting our individual progress, otherwise they are not necessary to know, because the method will work for most whether we drink 2 units a day or 20.
If you always drink the same drink like me, (95% of the time) for ease you can just count drinks to chart your progress, but if you chop and change your drinks you will have to keep working out the units, but don't worry if your calculations are different to anothers- you only need to compare you units to you!