Why do we use simple averages to record units?
There are several thousand alcoholic drinks available in differing strengths and sold in different ways; for example by the bottle, pint or by the glass.
With so many options and because there are many occasions when it won't be clear how much of something is used; for example someone may 'top up' your glass, it is unlikely that you will be able to record 'exact' measures.
Yes they do all add up – that's a fact. So should we be bothered about the details – about absolute accuracy?
The difference between alcoholic strength and the resulting 'units' is actually quite small – e.g. a pint of 4.2% beer (2.4 units) and a pint of 5.2% beer (2.9 units) is a difference of just 0.5 of a unit. Or the difference between a full bottle of wine at 12.0% and 13.0% is 0.7 units.
Yes they do all add up – so if you aim for drinking 'less' than 25 units (as an example) the difference is between drinking 11 pints of 4% beer over a period (24.9units) and 12 pints of 4% beer over the same period (27.2 units).
Many people in the UK are drinking at 'increasing risk' and 'high risk' levels. The use of units is a way of standardising a measure across different types and quantities of drink and as such is very helpful. Absolute accuracy is difficult and is unlikely to be necessary for those people who are looking to initially get an overview of their drinking.
As always with health guidance – if there is any doubt or concern on your part – please consult a professional for further advice.