Alcohol Intake & BAC Estimator
Estimate pure alcohol, standard drinks, and an approximate blood alcohol concentration (BAC) based on your inputs.
What this alcoholic drink calculator does
This tool helps you estimate three practical numbers: how much pure alcohol you consumed, how many standard drinks that represents, and your approximate BAC based on body weight, sex, and time.
- Pure alcohol: grams of ethanol consumed.
- Standard drinks: converted using common U.S. and U.K. definitions.
- Estimated BAC: an approximation using the Widmark formula.
How to use the calculator
1) Enter drink size and ABV
Enter the volume of one drink and its alcohol by volume (ABV). For example, a typical beer might be 12 oz at 5%, while wine might be 5 oz at 12%.
2) Enter how many drinks you had
Multiply equivalent drinks. If you had different beverages (for example, beer and spirits), run separate calculations and compare totals.
3) Enter body details and time
BAC estimates depend strongly on body weight and elapsed time. The longer the time window, the lower the estimated BAC, because the body metabolizes alcohol continuously.
Common ABV reference values
- Light beer: 3% to 4.2%
- Regular beer: 4.5% to 6.5%
- Strong IPA: 6.5% to 9%+
- Wine: 11% to 14%
- Fortified wine: 17% to 20%
- Spirits (vodka, whiskey, rum, gin): around 40%
- Liqueurs: often 15% to 35%
How the math works (simple explanation)
The calculator first converts your drink to pure ethanol:
- Pure alcohol per drink (ml) = drink volume × (ABV / 100)
- Pure alcohol per drink (grams) = ethanol ml × 0.789
Then it estimates BAC using a common Widmark-style approximation:
- BAC rises with more alcohol consumed.
- BAC falls over time at an average elimination rate (~0.015 per hour).
- Distribution factors differ by sex in this model.
Important limitations
No calculator can perfectly predict real BAC. Actual alcohol absorption and elimination vary based on food intake, medications, health status, sleep, hydration, drinking speed, and genetics.
- Use this as a planning and awareness tool, not a safety guarantee.
- Legal limits vary by country and region.
- Impairment can happen well before legal thresholds.
Practical safety guidance
- Set a transport plan before drinking.
- Alternate with water and pace your intake.
- Stop earlier than you think if you must function later.
- If uncertain, do not drive or operate equipment.
FAQ
What is a standard drink?
In the U.S., one standard drink contains about 14 grams of pure alcohol. In the U.K., one unit is 8 grams. This calculator shows both for convenience.
Why does BAC stay above zero for so long?
Alcohol is metabolized gradually. Time is the key factor for decreasing BAC; coffee, showers, and fresh air do not rapidly remove alcohol from blood.
Can I use this to decide if I am safe to drive?
No. Treat the result as informational only. If you consumed alcohol, the safest choice is to avoid driving entirely.