Morning After Calculator: When Does the Alcohol Clear?
Alcohol leaves the body slowly, and a night of drinking often runs into the next morning. Enter what you drank and the hour you stopped, and this estimates when the alcohol is likely to have left your blood — as a span of hours, because that is what the research gives, and never as a verdict on driving.
8 hr to 15 hr after your last drink at 11:30 pm, for 5.3 standard drinks
At the one-drink-an-hour rule of thumb, 5.3 standard drinks is about 5 hours of work on its own — and that rule is the fast end of the range, not the middle of it.
This is an estimate, not permission to drive. No calculator can tell you that you are under a limit or fit to drive — the only amount of alcohol that carries no risk behind the wheel is none.
The page opens on a worked example — four pints, stopped at half past eleven, at the default weight below. Change the drinks and the hour and it becomes yours.
No calculator can clear you to drive, and this one is not trying to.
It is arithmetic on population averages. It cannot measure your liver, your medication, the food you had or your impairment, and it is not a defence at a roadside stop. Impairment starts well below every legal limit, and being under one is not the same as being unimpaired. Drinkaware's advice is the honest version: avoid alcohol completely the night before you have to drive, and if you are not sure, do not drive. What the law says, country by country, is on the drink driving limit page.
Your night, drawn out to the afternoon
Eighteen hours from your last drink, so the hours you are actually asking about are always on it. Nothing here is drawn in the yard's green: no part of this is a measurement you can act on.
The two edges are the same night at two published elimination rates. That gap is not sloppiness — it is the honest width of the answer, and a page that printed one confident hour instead would be wrong more often and quieter about it.
The morning, hour by hour
Each hour taken at its first arrival after your last drink. No row is a green light: the third state is the estimate running out, which is a different thing from being clear.
| Morning | Hours since your last drink | What the estimate says |
|---|---|---|
| 5:00 am | 5 hr 30 min | Alcohol still in your blood on every estimate in the range. Still in you |
| 6:00 am | 6 hr 30 min | Alcohol still in your blood on every estimate in the range. Still in you |
| 7:00 am | 7 hr 30 min | Alcohol still in your blood on every estimate in the range. Still in you |
| 8:00 am | 8 hr 30 min | Inside the width of the estimate — the slow end still has alcohol in you. Inside the range |
| 9:00 am | 9 hr 30 min | Inside the width of the estimate — the slow end still has alcohol in you. Inside the range |
| 10:00 am | 10 hr 30 min | Inside the width of the estimate — the slow end still has alcohol in you. Inside the range |
A hangover is its own clue. Drinkaware puts it plainly: if you wake up with one you will almost certainly still have alcohol in your system. How long the hangover itself runs is a separate question, and the hangover calculator estimates it.
What did you drink?
Every chip below prints its own standard-drink value, worked out from its size and strength rather than typed in by hand.
Tap a drink to add it. Tap again for a second one.
A US standard drink is 14 grams of pure alcohol — NIAAA's definition. Anything you add here is converted to that unit.
You, and the hour you stopped
- Every drink is counted as already in your blood at the hour you stopped. Spread across an evening your real peak was lower, so a long slow night finishes sooner than this shows — the error runs in the cautious direction on purpose.
- Your liver clears alcohol at a pace you cannot change. The published physiological range is 10 to 35 mg per 100 mL of blood per hour; the band drawn above runs from 20 down to 10, which covers most people who are not drinking heavily every day. Regular heavy drinkers clear faster, at 25 to 35.
- A US standard drink is 14 grams of pure alcohol. The NHS puts one UK unit at 10 ml or 8 grams, around what an average adult processes in an hour — so "one drink an hour" is a floor, and a 14 gram drink is closer to an hour and three quarters.