You can't calculate your alcohol limit - so don't try.
The current legal limit for driving in the UK is 80mg of alcohol per 100ml of blood. In most European countries, the legal limit is lower at 50mg.
There is no failsafe guide as to how much you can drink and stay under the current limit. The amount and type of alcoholic drink, and your weight, sex, age and metabolism will all play their part.
The only safe course is not to drink and drive.
The quantity of alcohol in a half pint of beer is approximately the same as in a pub measure of spirits or a pub measure of port/sherry or a small glass of wine.
It is important to note that:
At twice the current legal limit you are at least 50 times more likely to be involved in a fatal accident.
After just 10 minutes, 50% of the alcohol consumed will have been absorbed into the bloodstream.
After an hour all the alcohol will have been absorbed.
Absorption is accelerated still further when drinking on an empty stomach. Long drinks made with mixers have a faster effect as they enter the bloodstream quicker.
At midnight, after an evening's drinking there may be 200mg/100ml of alcohol in the blood.
On getting up, there is still 90mg/100ml. You are still over the current legal limit and unfit to drive.
By lunchtime, elimination has continued to around 20mg/100ml. Your driving may still be impaired.
It is impossible to speed up alcohol elimination. Neither a shower, nor a cup of coffee, nor other ways of "sobering up" will help. It just takes time.
Getting rid of alcohol is a much slower process requiring hours rather than minutes.
Any alcohol, even a small drink, will impair driving ability.
Nearly one in seven of all deaths on the road involve drivers who are over the current legal limit. The risk of being involved in an accident increases rapidly with the amount of alcohol consumed.
Many motorists believe they are safe to drive if they are below the current legal limit. They are wrong. Even one drink will have an effect on driving ability and on your judgement, starting with your judgement about whether you should have another drink:
Causing death by careless driving while under the influence of drink or drugs - 10 years imprisonment and a disqualification of at least two years.
Driving or attempting to drive while over the legal limit or unfit through drink - 6 months imprisonment plus a fine of £5000 and a disqualification of at least 12 months (3 years automatic ban if convicted twice in ten years).
In charge of a vehicle while above the current legal limit or unfit through drink - 3 months imprisonment plus a fine of £2500 and a disqualification.
Refusing to provide a specimen - 6 months imprisonment plus a fine of £5000 and a disqualification of at least 12 months
If convicted of a drink drive offence you may be referred to a rehabilitation course.
You will become a high risk offender if:
In all these cases, you will have to satisfy an approved doctor that you do not have a drink problem before you can get your license back (and you will have to pay for the medical).
3500 people are killed or seriously injured each year in drink drive accidents
The only safe course is to not drink and drive
Any alcohol, even a small drink, will impair driving ability
You don't need to mix drinking and driving
Avoid the problem: