Driving decision support
Drink Drive Calculator: When Is It Safe to Drive?
Enter what you drank and when - or your current BAC - to see when you drop below your country's legal driving limit.
Average clearance
0.015% / hour
The timeline uses the standard BAC elimination planning rate.
Country limit overlay
0.00-0.08%
Select your country to place the legal limit on the timeline.
Safest driving choice
0 drinks
Below the legal limit is not the same as unimpaired.
Important safety notice
This calculator provides estimates based on average metabolism. Individual results vary significantly. BAC calculators cannot account for all factors that affect impairment. If there is any doubt, do not drive. The only safe amount of alcohol before driving is none.
Calculator
Estimate your driving timeline
Use the drink-entry mode when you know what you consumed. Use the BAC mode if you already have a breath-test reading or a current estimate and want a direct sober-up timeline.
Drink drive calculator
Preparing current-time fields...
Section 1
How This Calculator Works
This calculator uses a Widmark-style formula, the same general family of equations used for educational, medical, and forensic BAC estimation. It estimates BAC from drink volume, ABV, body weight, and sex, then applies an average alcohol elimination rate of 0.015% BAC per hour. For a deeper formula walkthrough, see how BAC works.
The calculator is intentionally a planning estimate, not a clearance certificate. Individual metabolism, medications, food intake, liver health, fatigue, exact pour size, and breathalyzer accuracy can all move the real result. Use the main BAC calculator for a fuller drink-by-drink session estimate.
Treat the output as a minimum wait time. If the tool says you may fall below the legal limit at 1:45 AM, a conservative decision is to wait longer, use alternative transport, or avoid driving entirely.
Section 2
Legal Limits by Country: What the Calculator Uses
The country selector uses the general adult driving limit as a planning reference. Many places apply stricter limits to professional drivers, learner drivers, and drivers under a certain age. The limit is a legal threshold, not a safety target.
| Country | General Limit | Under-21 / Learner | Professional Driver |
|---|---|---|---|
| United States | 0.08% | 0.00-0.02% (varies by state) | 0.04% (CDL) |
| United Kingdom | 0.08% | 0.08% (same) | 0.08% (same) |
| Scotland | 0.05% | 0.05% (same) | 0.05% (same) |
| Australia | 0.05% | 0.00% | 0.02% |
| Canada | 0.08% | 0.00% | 0.04% |
| Germany | 0.05% | 0.00% | 0.00% |
| France | 0.05% | 0.02% | 0.02% |
| Japan | 0.03% | 0.03% | 0.03% |
| Sweden | 0.02% | 0.02% | 0.02% |
| Czech Republic | 0.00% | 0.00% | 0.00% |
Full limits for 78 countries are in alcohol laws by country. To understand what different BAC levels feel like, compare the thresholds in the BAC chart.
Section 3
The Morning-After Risk: Why Sleep Does Not Clear Alcohol
The most common drink-driving question is often about tomorrow morning, not the trip home tonight. Sleep does not accelerate alcohol elimination. The liver processes alcohol at about the same pace whether you are awake or asleep.
A heavy night that ends around 1:00 AM with a peak BAC near 0.18% can still leave a BAC close to 0.09% at 7:00 AM, above the adult driving limit in many countries. Use the target-drive-time setting before you go to bed, and read more in how long does alcohol stay and alcohol and driving.
Section 4
Why Your Actual BAC May Differ from the Estimate
The timeline is only as good as its inputs and assumptions. Use these factors as a checklist before trusting a narrow margin near the legal limit.
Drinking pace within a session
If several drinks were consumed rapidly near the end of the night, your peak BAC and residual BAC may be higher than a simple average-pace estimate suggests.
Food intake
Food can slow absorption and lower the peak. Drinking on an empty stomach can raise the peak. The calculator cannot know what or when you ate.
Individual elimination rate
The 0.015% per hour rate is an average. Some people clear closer to 0.010% per hour, which means the real wait can be longer.
Medications
Some medicines slow alcohol metabolism or amplify impairment without changing BAC. Check the alcohol and medications guide before assuming the number tells the whole story.
Drink strength and size
A higher-ABV craft beer, a generous wine pour, or a double spirit entered as a single drink can make the estimate too low. When unsure, enter the higher amount.
Tolerance versus impairment
Feeling sober is not proof of safe driving. Tolerance changes how alcohol feels, not the measurable impairment to reaction time, vision, and judgment.
Related pages
Plan the safer next step
BAC Calculator
Calculate your blood alcohol content drink by drink with a full session timeline and your country's legal limit shown.
Sober-Up Calculator
Know your current BAC? Enter it directly to see when you reach zero and when you drop below the legal limit.
Alcohol and Driving
How alcohol impairs reaction time, vision, and judgment, with crash-risk context at different BAC levels.
Alcohol Laws by Country
Legal BAC driving limits for 78 countries, including professional driver and under-age limit context.
FAQ
Drink Drive Calculator FAQ
Common questions about using BAC estimates for driving-time planning.
Enter your drinks, body weight, sex, country, and the time you need to drive into the calculator above. It estimates your current BAC and when you may drop below the selected legal limit. Treat the result as an estimate, not proof that you are safe to drive.
It depends on how much you drank, your weight, sex, and local legal limit. As a rough guide, two standard drinks often take 2-3 hours to clear, four drinks can take 4-6 hours, and eight drinks can take 8-12 hours or more. Use the calculator for a situation-specific estimate and add a safety margin.
One standard drink often produces about 0.02-0.03% BAC for an average adult, below many legal limits. But measurable impairment can begin around 0.02% BAC, and some countries or driver categories have zero or near-zero limits. The safest amount before driving is none.
No. Coffee, food, water, exercise, and sleep do not meaningfully speed alcohol elimination. The liver processes alcohol at roughly 0.015% BAC per hour on average. Coffee may make you feel more alert, but it does not lower BAC.
It uses a Widmark-style BAC estimate and the standard 0.015% per hour elimination rate, which are useful planning assumptions. It cannot account for individual metabolism, liver health, medications, food intake, exact pour size, or breathalyzer calibration. A breathalyzer is the only practical real-time BAC measurement.
Common adult limits are 0.08% in the United States, United Kingdom, and Canada, and 0.05% in Australia and much of Europe. Some countries use 0.02%, 0.03%, or zero tolerance. Professional, learner, and under-age drivers often face stricter limits.