Drink Driving Calculator UK
Drink Driving Calculator
Driving a vehicle whilst over the legal limit for alcohol is a serious offence. In the UK, thousands of motorists are found guilty of drink driving related offences each year. The police and the courts like to ‘process’ drink driving prosecutions very quickly. This can lead to motorists feeling pressured into making hasty decisions, often without full knowledge of the options available.
M.A.J. Law has defended motorists across England and Wales for more than two decades. We know what the police look for, what the courts expect and where the defence opportunities are.
How does this drink drive calculator work?
This calculator gives you an estimate of your Blood Alcohol Content (BAC) based on the type and number of drinks you’ve had based on the alcohol in those drinks. It also gives you a rough estimate of how long you should wait before your BAC is likely to be below the legal limit.
On average the body removes one unit of alcohol per hour. The calculator applies this rate, plus one additional hour for the first drink to get into your bloodstream. It then rounds up to the nearest half hour to give you a conservative estimate.
*Just note this calculator is not a breathalyser. It can’t tell you with complete certainty whether you are over the limit. Only a type-approved breathalyser or blood analysis can do that.
If you have any doubt at all, do not drive.
What is the drink drive limit in the UK?
The drink drive limit is the same across most parts of the UK with the only outlier being Scotland, which reduced its limit in December 2014.
The drink drive limit is measured in three ways:
- The alcohol in your breath
- The alcohol in your blood
- The alcohol in your urine
Police most often use a breath test at the side of the road, with a blood or urine test used to confirm a positive reading.
|
Region |
Breath (µg/100ml) |
Blood (mg/100ml) |
Urine (mg/100ml) |
|
England |
35 |
80 |
107 |
|
Wales |
35 |
80 |
107 |
|
Northern Ireland |
35 |
80 |
107 |
What affects your blood alcohol level?
People don’t process alcohol at the same rate so if you’ve had the same number of drinks as a friend, you could have different BAC readings. The factors that can impact how quickly you process alcohol include:
Body weight
Alcohol distributes through water in your body, and heavier people tend to have more body water that dilutes alcohol and produces a lower BAC result than a lighter person drinking the same amount.
Sex
Men typically have a lower body fat percentage and more body water than women, which means men usually have a lower BAC reading than women after the same number of drinks.
Drinking speed
The faster you drink, the higher your BAC will be. The rate your liver can process alcohol is pretty fixed, so if you drink alcohol quicker than it can process, the higher your BAC will be compared to someone drinking the same amount but over several hours.
Food
Being full because you’ve eaten before drinking can slow how quickly alcohol is absorbed into your bloodstream. This won’t reduce the total amount of alcohol your body needs to process, but it can delay when your blood alcohol content peaks.
Medication
Some medications can impact how quickly alcohol is absorbed and processed in your body. If you’re taking any medication it’s important to understand what effect drinking alcohol will have.
Age and metabolism
Younger people usually process alcohol quicker than older people and heavy drinkers can also have more active livers that process alcohol faster than people who don’t drink very often. Any liver conditions can also impact how quickly alcohol is broken down.
Fat vs muscle
People with more muscle tend to have more body water, which absorbs alcohol quicker than people with more fat than muscle. So two people who weigh the same but have different body compositions can have different BAC levels.
What happens if you’re caught drink driving?
Drink driving is a serious offence and cases in the UK often move quickly through the court system. If you’re caught or charged with drink driving you should seek legal advice straight away because decisions made in the very early stages of your case can affect the outcome later on.
The “standard” penalties for a first drink driving conviction in England and Wales can include:
- A minimum 12-month driving ban
- Up to six months in prison depending on the severity
- Unlimited fines
- A criminal record
If you’re convicted of drunk driving twice within 10 years, the minimum ban goes up to three years. If an accident or incident occurs while you’re drink driving, or if a child is in the vehicle, your sentence can be much harder.
M.A.J. Law has successfully defended hundreds of drivers across England and Wales in these situations. We identify procedural errors challenge the reliability of evidence and ensure the court hears all the details and circumstances relevant to your case.
If you’ve been charged with drink driving, get some free legal advice today
Call 0151 422 8020
Is it safe to drive the morning after drinking?
Many drink driving arrests happen the morning after a night out rather than on the night because many people assume they’ve left enough time. But a driver who stopped drinking at midnight could still be over the limit at 8am based on the factors we’ve talked about.
One study by Confused.com found that 28% of drivers in the UK had driven the morning after drinking and could have still been over the limit, with 35% of those judging their fitness to drive on how they felt.
Tiredness, dehydration and any lingering effects of alcohol can mask impairment while your BAC is still over the legal limit.
Use the calculator below to get a rough estimate when your BAC is likely to return to the legal limit. If you’re in any doubt about whether you should drive, don’t.
