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First things first…

Let’s make one thing absolutely clear at the outset - this calculator  is not intended to help you work out how much you can drink on a night out before driving home.

If you are drinking any amount of alcohol on a night out - even one drink - you should leave the car at home and make alternative arrangements.

And the calculator won’t help you if you are arrested for drink driving.

What it will do is enable you to calculate roughly when it will be safe for you to drive the morning after drinking alcohol. And it can help you calculate when to stop drinking alcohol if you have to drive the following morning.

How the 'Morning After Calculator' works

The calculator allows one hour for each unit of alcohol, plus an additional hour for the first drink to allow for the alcohol to enter the bloodstream. It then rounds up the calculation to the nearest half hour.

The calculator bases its calculation from the time you stop, not when you start drinking. Some people say this is over-cautious, but we’d rather be safe than sorry.

The 'hours before driving' calculation is not based on any drink drive limit - it is the length of time when the alcohol in the drinks you've consumed is likely to have passed through your body. This is when we suggest you will be 'safe to drive'.

How to use the calculator

Simply tot up the drinks you consumed the night before - or better still, use the calculator smartphone app to keep track of what you’re drinking while you’re out - and the calculator will store them and give you a rough calculation of when you will be safe to drive.

We’ve included a fair number of drinks, but if you can’t find the exact drink you consumed there may be something of similar alcoholic content (ABV).


The Morning After Calculator is an application intended to be used strictly as an aid for approximating one's blood alcohol content and does not constitute legal justification for driving after drinking.

In all cases it is safest to never drive after drinking and to avoid heavy drinking if you are driving the next day.

By using this application you assume all risk and responsibility.

About the Morning After campaign

The morning after campaign, which has been running for several years, is designed to help normally responsible people avoid the risk of a drink drive conviction - or worse still, cause a collision or casualties while ‘over the limit’ - by highlighting how long it takes for alcohol to pass through the body.

The Morning After Calculator App has been designed by Stennik and developed by SoftApps.