BAC Sober Time Calculator
Estimate blood alcohol and how many hours until you are back to zero.
Enter your values
Choose one of: Typical male (r = 0.68), Typical female (r = 0.55).
Enter the body weight in kg.
Enter the standard drinks in drinks.
Enter the alcohol per drink in g.
Enter the hours since first drink in hours.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Estimated BAC now
- 0.08%
- Status
- over the 0.05% limit
- Hours to 0.00%
- 5.3
- Hours to under 0.05%
- 2
- Peak BAC reached
- 0.11%
- Total alcohol
- 56 g
Working
- 1(56 g / (75 kg x 0.68)) x 100 = 0.11% peak
- 2minus 0.015 x 2 h = 0.08%
Quick answer
The Widmark formula estimates BAC from grams of alcohol, bodyweight and a body-water constant, then subtracts about 0.015% per hour of metabolism.
BAC = (grams / (kg x r)) x 100 - 0.015 x hours
At a glance
| What it does | Estimate blood alcohol and how many hours until you are back to zero. |
|---|---|
| Category | Health |
| Inputs needed | Body composition constant, Body weight, Standard drinks, Alcohol per drink, Hours since first drink |
| Main output | Estimated BAC now |
| Formula | BAC = (grams / (kg x r)) x 100 - 0.015 x hours |
| Cost | Free — no sign-up, no download |
How to use the BAC Sober Time Calculator
- 1Count standard drinks: a 14 g drink is 350 ml of 5% beer, 150 ml of 12% wine or 45 ml of spirits.
- 2Enter your weight and the hours since your first drink.
- 3Never drive on an estimate — treat the sober-time figure as a minimum, not a green light.
Inputs explained
- Body composition constant
- Choose one of: Typical male (r = 0.68), Typical female (r = 0.55).
- Body weight(kg)
- Enter the body weight in kg.
- Standard drinks(drinks)
- Enter the standard drinks in drinks.
- Alcohol per drink(g)
- Enter the alcohol per drink in g.
- Hours since first drink(hours)
- Enter the hours since first drink in hours.
Worked example
Using the values the calculator loads with:
Inputs
- Body composition constantTypical male (r = 0.68)
- Body weight75 kg
- Standard drinks4 drinks
- Alcohol per drink14 g
- Hours since first drink2 hours
Results
- Estimated BAC now0.08%
- Statusover the 0.05% limit
- Hours to 0.00%5.3
- Hours to under 0.05%2
- Peak BAC reached0.11%
- Total alcohol56 g
- (56 g / (75 kg x 0.68)) x 100 = 0.11% peak
- minus 0.015 x 2 h = 0.08%
Frequently asked questions
How accurate is a BAC estimate?
The Widmark formula is a population average. Food, medication, liver health and drink strength can shift real BAC well above or below the estimate.
Can I speed up sobering up?
No. Coffee, cold showers and food after drinking do not change the metabolism rate of roughly 0.015% per hour.
What do I need to enter into the BAC Sober Time Calculator?
Just 5 values: body composition constant, body weight, standard drinks, alcohol per drink, hours since first drink. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the BAC Sober Time Calculator work out the answer?
The Widmark formula estimates BAC from grams of alcohol, bodyweight and a body-water constant, then subtracts about 0.015% per hour of metabolism. It applies the formula BAC = (grams / (kg x r)) x 100 - 0.015 x hours and shows the working so you can check each step by hand.
Is the BAC Sober Time Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.