New research has revealed that 14% of drivers in the last six months may have been over the drink-drive limit due to a lack of understanding of alcohol measures.

When asked to pour a single measure of spirits, one in six poured a double and one in 12 poured a quadruple measure

Due to the impact of Covid-19 more people will be drinking at home rather than drinking out in pubs and restaurants and the research by Direct Line Car Insurance saw people pour excessively large glasses containing several units of alcohol.

In a practical experiment testing drivers’ ability to pour set limits of alcohol, 56% of the 100 participants overpoured when asked to fill a glass with standard pub measures of wine.

When asked to pour a single (25ml) measure of spirits, three-quarters (75%) overpoured and one in six (18%) poured a double measure while almost a quarter (24%) poured at least a treble (75ml). One in 12 (8%) went so far they poured 100ml, a quadruple measure.

It is not just when pouring for themselves there is an issue, people are unable to judge volumes of alcohol when a glass is poured for them. When looking at glasses of wine, only 30% of people could correctly identify a 125ml glass, while almost a third picked a glass with more alcohol in. When asked to identify a 175ml glass of wine, only one in eight (12 per cent) managed to select correctly, with 39% choosing a glass with a greater volume.

And over the last six months alone, nearly five million (14%) motorists have driven their car when they thought they were over the limit, with over two million (6%) believing this to be because the person serving them poured larger drinks than they realised.

The survey also revealed widespread confusion about the legal limit for consuming alcohol and driving across the UK. Just 4% of drivers in Scotland and just 12% of drivers living in England, Wales or Northern Ireland knew what the legal limit is for where they live.

Steve Barrett, head of motor insurance at Direct Line, commented: “It isn’t just the safety of the driver and passengers in their car that are at risk if a driver is over the limit, it is everyone else on the road too. This experiment shows that home measures are often substantially more generous than those measured in a pub or restaurant and how just one glass of wine or a spirit poured at home could put a driver over the drink drive limit.”

He added: “If a driver chooses to have a drink at home or at someone else’s house within their ‘bubble’, it is vital they know how much alcohol they are consuming, before getting behind the wheel. The only way anyone can be sure that they are safe to drive in this situation, is if they don’t have any alcohol at all.”