Alcohol Blood Limit UK & Legal Driving Limits

In the UK, understanding your alcohol blood limit is crucial for safe and legal driving. The blood alcohol content UK limit is 0.08% in England, Wales, and Northern Ireland, and 0.05% in Scotland. If your blood alcohol content for driving exceeds the legal blood alcohol content level, you could face fines, bans, or even criminal charges. Our calculator helps you stay within the blood alcohol content legal limit, giving you peace of mind before getting behind the wheel.

Alcohol poisoning signs

Alcohol poisoning is a serious and potentially life-threatening condition that occurs when a person consumes a dangerous amount of alcohol in a short period. Signs of alcohol poisoning include:

  • Confusion and inability to stay awake
  • Slurred speech and loss of coordination
  • Vomiting
  • Pale or blue-tinged skin, especially around lips or fingertips
  • Slow or irregular breathing (less than eight breaths per minute or gaps of more than 10 seconds between breaths)
  • Seizures
  • Loss of consciousness or being unresponsive

If you suspect alcohol poisoning, call the emergency immediately, as urgent medical attention is required.

Will Alcohol Affect a Blood Test?

Yes, alcohol can affect a blood test—especially tests related to liver function, blood sugar, or medications. If you're scheduled for a blood test, it's best to avoid drinking alcohol at least 24 hours beforehand to get accurate results.

What Blood Alcohol Level is Drunk?

A person is typically considered drunk when their blood alcohol level reaches 0.08% or higher. At this point, coordination, judgment, and reaction time are significantly impaired. Use our calculator to estimate your BAC and know when it’s no longer safe to drive or make decisions.

Alcohol Blood Content

Alcohol blood content, also known as BAC (blood alcohol concentration), measures the amount of alcohol in your bloodstream. It helps determine how impaired you may be after drinking. Our calculator makes it easy to estimate your BAC based on your weight, gender, and number of drinks.

Breathalyzer measurement units

In the UK, Breathalyzer measurement units are typically expressed as Blood Alcohol Content (BAC), which shows the amount of alcohol in your system. The most common units are:


Milligrams of alcohol per 100 millilitres of blood (mg/100ml), micrograms per 100 millilitres of breath (µg/100ml), and milligrams per litre of urine (mg/L)

For example, the legal drink driving limit in England, Wales, and Northern Ireland is 80mg per 100ml of blood, 35µg per 100ml of breath, or 107mg per 100ml of urine. Scotland has lower limits. You can use our blood alcohol content calculator to estimate your BAC.

Source: BACtrack - bactrack.com/pages/breath-alcohol-units-of-measurement

Applied error margin

Breathalyzer devices in the UK are not 100% accurate and have a certain margin of error. Police-approved breathalysers typically have a tolerance of ±2 micrograms per 100ml of breath or ±6mg per 100ml of blood. For example, a reading of 35µg/100ml could actually be between 33 and 37µg/100ml. This margin does not exempt drivers from prosecution if they are over the legal limit.

When can you drive after drinking?

On average, it takes about one hour for your body to process one unit of alcohol. However, factors like body mass, gender, food intake, and health can affect this. For example, it may take 3 hours to eliminate the alcohol from a pint of beer (4%), a small glass of wine (12%), or a single measure of spirits (40%). The safest approach is to use a calculate blood alcohol content tool and avoid driving until you are certain you are under the legal limit.

Most popular breathalyzer

One of the most popular breathalysers in the UK is the AlcoSense Excel, known for its accuracy and reliability. UK police commonly use devices from Dräger and Lion Laboratories for roadside testing. For personal use, many drivers rely on the AlcoSense range to check their BAC before driving.

How long does it take for a BAC of 0.1% to be eliminated from the blood?

It typically takes 5 to 8 hours to eliminate 0.1% BAC (100mg/100ml) from your blood, as the body removes about 0.012–0.020% BAC per hour. Use a blood alcohol content calculator to estimate your elimination time.

How to sober up faster

Drinking water may help you feel better, but it does not speed up the breakdown of alcohol in your body. Only time reduces your BAC. Using a blood alcohol content calculator or alcohol points calculator can help you estimate when you will be sober.

Alcohol unit

In the UK, a standard unit of alcohol contains 10ml (8g) of pure alcohol. To calculate units: volume (ml) × strength (%) ÷ 1000. For example, 500ml of 5% beer equals 2.5 units, 175ml of 12% wine equals 2.1 units, and 25ml of 40% spirits equals 1 unit.

How long does it take to completely remove alcohol from the body?

Alcohol can be detected in your breath for up to 24 hours, in urine for up to 48 hours, in blood for up to 24 hours, in saliva for 1–5 days, and in hair for up to 90 days. Use a calculate blood alcohol content tool for more personalised estimates.

Alcohol sales time

Alcohol sales hours in the UK depend on country and local authority. In England and Wales, most shops can sell alcohol from 8 a.m. to 11 p.m., though some have 24-hour licences. In Scotland, off-licence sales are generally allowed from 10 a.m. to 10 p.m. Sunday and holiday hours may differ, and local councils may set additional restrictions. Always check local rules for specifics.

How does alcohol affect the liver?

Alcohol is broken down in the liver by enzymes. Excessive drinking can lead to fatty liver disease, hepatitis, or cirrhosis. These conditions can be irreversible, so it’s important to drink in moderation and use tools like a blood alcohol content calculator to track your intake.

What are the long-term effects of alcohol?

Long-term alcohol consumption can lead to serious health issues, including heart disease, high blood pressure, liver damage, and neurological problems. It also increases the risk of developing certain cancers, such as liver, mouth, and oesophageal cancer. Mental health conditions like depression and anxiety are also more common among those who regularly drink above the recommended alcohol limits.

How does alcohol affect behavior and mood?

Blood Alcohol Content (BAC) directly affects behaviour and cognitive function. At lower BAC levels (0.02%–0.05%), you may feel relaxed or more sociable. However, as BAC rises above 0.08%, your motor skills, coordination, and judgement become impaired, increasing the risk of accidents, poor decision-making, and aggressive behaviour. Using a blood alcohol content calculator can help you understand your limits and avoid dangerous situations.

Does alcohol help fight stress?

Although alcohol may seem to relieve stress in the short term, regular drinking can actually increase anxiety and stress over time. Relying on alcohol as a way to manage stress can quickly lead to dependency and other health problems. Health experts recommend finding healthier ways to cope with stress, such as exercise or talking to someone you trust.

How does alcohol affect a person's behavior and well-being?

Blood Alcohol Content (BAC) significantly affects a person's behaviour and cognitive abilities. Different BAC levels can lead to various effects on mood, judgement, and physical coordination:

Low BAC levels (0.02% – 0.05%)

  • You may feel mildly relaxed and in a better mood.
  • Decision-making may be slightly impaired, and you might become more talkative or expressive.

Moderate BAC levels (0.05% – 0.08%)

  • Attention span and perception are reduced.
  • Coordination and reaction times worsen, increasing the risk of accidents.
  • Inhibitions decrease, and emotions may become more pronounced.

High BAC levels (0.08% and above)

  • Motor skills and cognitive functions are significantly impaired.
  • Speech may become slurred, and balance is affected.
  • Impulsivity and risk of aggression increase.
  • Nausea and vomiting may occur.

Very High BAC levels (0.20% and above)

  • There is a risk of memory loss and loss of consciousness.
  • Serious health risks arise, including breathing difficulties.
  • At BAC above 0.40%, there is a risk of coma or fatality.

The effects of alcohol can vary depending on individual factors such as weight, gender, and overall health. Remember, in England, Wales, and Northern Ireland, the legal drink driving limit is 0.08% BAC (80mg per 100ml of blood), while in Scotland it is lower at 0.05% BAC (50mg per 100ml of blood). Always use a blood alcohol content calculator to stay safe and within the law.

How to recognize if someone has an alcohol problem?

Common signs of alcohol problems include a strong urge to drink, difficulty controlling your drinking, and using alcohol to cope with stress or negative emotions. These behaviours can harm your health, relationships, and work life. If you notice these signs, it may be time to seek advice or support for alcohol misuse.