It is one of the most common questions about alcohol, and one of the hardest to get a straight answer to: can I drive tomorrow?
We are not going to answer it. No article, no calculator and no app can decide whether you in particular are fit to drive on a given morning — that answer exists only in a breath test. What we can do is explain what actually happens in your body overnight, how long clearing the alcohol takes, and why your own judgement is such a poor instrument for measuring it. The rest is your decision.
Why the morning after catches people out
During the evening you can tell you have been drinking. You feel it in your balance, your voice, your judgement. By morning most of that feeling is gone — but it went because you slept, not because the alcohol left.
That is the whole problem with morning-after alcohol. The signals you normally trust to judge your own state belong to the experience of being drunk, and that fades long before your blood alcohol does. You can be rested, wide awake and feel entirely normal with enough alcohol in your blood to be charged with drink-driving.
How long does clearing it actually take?
The body breaks alcohol down at a fairly steady rate — on average 0.10–0.15 per mille per hour. The rate cannot be changed, and it takes no notice of how you feel.
Working backwards from a peak makes the picture concrete. The table assumes standard drinks of 12 grams of pure alcohol, the Widmark formula, and elimination at 0.15 per mille an hour. Hours are counted from the last drink:
| Person | Standard drinks | Estimated peak | Time to 0.0 ‰ |
|---|---|---|---|
| Man, 75 kg | 4 | about 0.9 ‰ | about 6 hours |
| Woman, 65 kg | 4 | about 1.2 ‰ | about 8 hours |
| Man, 75 kg | 6 | about 1.4 ‰ | about 9 hours |
| Woman, 65 kg | 6 | about 1.8 ‰ | about 12 hours |
| Man, 75 kg | 8 | about 1.8 ‰ | about 12 hours |
| Woman, 65 kg | 8 | about 2.5 ‰ | about 16 hours |
Six drinks for a 65 kg woman means alcohol can still be present late the next morning even if the last glass was at midnight. Eight drinks reaches into the afternoon.
Two notes on the numbers. The formula assumes the whole amount is in your blood the moment you stop drinking, which overstates the peak after a long evening — over five hours of drinking the liver clears some of it as you go. So the error leans towards caution. At the same time individual variation is wide: sex and weight are only two of the factors, and food, sleep, medication and how you happen to be that day all matter too. Treat the table as an order of magnitude, not an answer.
To run your own numbers, there is a BAC calculator on this blog.
Why we publish no “you can drive now” time
Plenty of calculators work out how many hours until you drop below the legal limit and present that number as a kind of all-clear. Ours does not, and that is deliberate.
Stating what the limit is in a given country is a matter of fact and belongs on a page like this one. Working out that you specifically have cleared it is something else: it is a green light to get into a car, built on an estimate that does not know what you actually drank, how you feel, or how your body is behaving today. A number like that looks precise and is not.
So the calculator shows an estimated level right now, and an estimated time to 0.0 ‰. Both describe the alcohol. Neither describes a state you are in.
Myths about sobering up faster
| Myth | What actually happens |
|---|---|
| Coffee sobers you up | Caffeine makes you more alert. Your blood alcohol is exactly the same — and alert and drunk is more dangerous than tired and drunk. |
| A cold shower helps | No measurable amount of alcohol leaves the body through your skin. |
| Food soaks up the alcohol | Food before and during drinking slows absorption and lowers the peak. Afterwards it changes nothing. |
| You burn it off faster asleep | The liver works at the same rate whether you are asleep or awake. Sleep makes you feel better, not sober sooner. |
| You can sweat or exercise it out | Only a few per cent leaves through breath, sweat and urine. The rest goes through the liver, at its own pace. |
There is no shortcut. Time is the only mechanism that works.
What the law says about the morning after
The law makes no distinction by time of day. The limits are the same at seven in the morning as at eleven at night:
- Drink-driving — from 0.2 per mille. A fine or up to six months in prison, and the licence is normally revoked.
- Aggravated drink-driving — at 1.0 per mille or above. Up to two years in prison and a disqualification period of at least one year.
Swedish police need no suspicion of any other offence to carry out a breath test, and checks happen in the morning as much as at night. Having slept well and feeling fine is not a circumstance the law takes into account.
Those are the Swedish figures. Drive abroad and both numbers change — see Drink-Driving Limits by Country.
Hungover is not the same as sober
Even once your level genuinely is back to zero, you are not necessarily in a state to drive. A hangover usually means too little sleep, dehydration and a headache, and that shows up in reaction time, attention and patience — all the things traffic asks of you. Tiredness behind the wheel is a safety problem in its own right, entirely separate from alcohol.
Zero per mille is a minimum requirement, then, not a certificate that you are in shape.
What actually helps
- Decide the night before. The easiest decision is the one you make before the first drink: leave the car at home, plan a route on public transport, or budget for a taxi in the morning.
- Count the drinks as you go. It is far easier than reconstructing the evening the following day, and it is the entire point of logging in the moment.
- Measure instead of guessing. A breath test is the only thing that shows what is really in your blood. Mypromille can pair with a Bluetooth breathalyzer and show a real measurement alongside the estimate.
- If you are in any doubt at all, leave the car. The cost of taking the bus is low. The cost of being wrong is your licence, and potentially a great deal more.
Frequently asked questions
How long does alcohol stay in your body after a night out?
Can you still have alcohol in your blood in the morning?
Can you speed up how fast alcohol leaves your body?
What are the drink-driving rules the morning after?
How can I know my level in the morning?
Keep track while the evening is happening
It is much easier to know where you stand in the morning if you were counting the night before. Mypromille logs your drinks as you go and follows your estimated level in real time — and can show a real measurement if you have a breathalyzer.
The app is available for iPhone, Android and straight in the browser.
Sources: Systembolaget on alcohol elimination, Systembolaget on drink-driving and Wikipedia — Rattfylleri. This is general information, not legal advice.