Alcohol Elimination Time Online Calculator

Alcohol Elimination Calculator estimates blood alcohol concentration (BAC) over time from your inputs and projects when you will reach set thresholds. It implements Widmark’s equation with sex-specific body water constants and a fixed average elimination rate. Standard drink sizes follow national definitions. This is an estimate, not legal or medical advice.

Alcohol Elimination Calculator

Profile

Body weight

Total standard drinks

Standard drink size

Drinking duration (hours)

Hours since last drink

Elimination rate β (%BAC per hour)

Typical range 0.010–0.020 %/h

Totals

Alcohol intake: —

Total time since first drink: —

Estimates

Peak BAC at end of drinking: —

Current BAC: —

Time to thresholds

To 0.08%: —

To 0.05%: —

To 0.00%: —

Notes

Estimates only. Individual metabolism varies. Not medical or legal advice.

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What this calculator does

Converts your drinks to grams of pure ethanol using your selected standard (8 g, 10 g, 12 g, 14 g, or custom).
Estimates peak BAC at the end of your drinking window via Widmark’s distribution with r≈0.68 for typical males and r≈0.55 for typical females, or a custom r.
Subtracts metabolic elimination from peak to “now” using a constant rate β (default 0.015 %/h).
Reports current BAC and time to reach 0.08 %, 0.05 %, and 0.00 %.

Inputs explained

Profile (r). Widmark body-water constant. Typical male ≈0.68. Typical female ≈0.55. Custom r allowed for atypical body composition.
Body weight. Enter in kg or lb. The tool converts lb→kg internally (×0.45359237).
Total standard drinks. Count of “standard” drinks you consumed. The size depends on the jurisdiction.
Standard drink size. Choose US 14 g, AU/NZ 10 g, EU 12 g (approximate), UK 8 g, or enter a custom grams value.
Drinking duration. Hours from the first sip to the last sip.
Hours since last drink. Time elapsed after the last sip.
Elimination rate β. Default 0.015 % per hour. Accepts 0.010–0.020 %/h to reflect individual variation.

Outputs explained

Alcohol intake. Total grams = number of drinks × grams per drink.
Total time since first drink. Drinking duration + time since last drink.
Peak BAC at end of drinking. Estimated BAC at the last sip, before further elimination.
Current BAC. Peak minus β × hours since last drink, floored at 0.
Time to thresholds. Linear time from current BAC to 0.08 %, 0.05 %, and 0.00 % assuming constant β. Legal limits vary by country and situation.

Formulas and units

Standard drink conversion: grams = drinks × grams_per_drink. U.S. standard drink = 14 g ethanol; U.K. unit = 8 g; Australia/NZ standard drink = 10 g.

Widmark distribution: peak_BAC(%) ≈ (grams / (r × body_weight_kg × 10)) − β × drinking_duration_hours. The factor “10” converts g/kg to g/100 mL (%). r≈0.68 male, r≈0.55 female, custom allowed.

Elimination: current_BAC(%) ≈ max(0, peak_BAC − β × hours_since_last_drink). Use β≈0.015 %/h by default.

Assumptions and limits

Zero-order elimination. Near typical concentrations, ethanol is eliminated at an approximately constant rate per hour. This is a model; rates vary by person and context.
Absorption and peak timing. The tool treats the entered “drinking duration” as the window to reach peak. Real absorption varies with food, beverage strength, and gastric emptying.
Population averages. r and β are averages. Illness, liver function, medications, tolerance, and genetics alter kinetics. Estimates can deviate materially from measured BAC.
Jurisdictional standards. “Standard drink” grams differ by country. Pick the correct standard or use a custom grams value.
No impairment guarantee. Any alcohol can impair. Do not use results to decide whether to drive.

Choosing settings

Pick the correct drink standard. Use the jurisdiction that matches your labels, or custom grams if you know the exact ethanol amount.
Adjust β if you have data. Lab or forensic reports sometimes imply higher or lower personal β. Stay within ~0.010–0.020 %/h unless you have reliable evidence.
Use custom r sparingly. Change r only when you have a defensible reason (e.g., clinical guidance, body composition studies). Otherwise use sex-typical values.

FAQ

Why can estimates differ from breathalyzer or blood tests? Devices measure actual ethanol in breath or blood at that moment. This tool uses population parameters and your inputs, so error accumulates from r, β, drink strength, timing, food, and measurement noise.

Does coffee, showers, or exercise speed elimination? No. Metabolism rate is largely fixed; you must wait for the liver to clear ethanol.

Why is the UK “unit” 8 g while the U.S. standard drink is 14 g? Countries define reference drinks differently for labeling and guidelines. Pick the correct standard to avoid errors.

Is elimination truly linear? Ethanol elimination is approximately zero-order near common BACs, though models and individual data show variability and nonlinearity at extremes.

Safety

Do not use this calculator to decide whether to drive or operate machinery. Any alcohol can impair performance, and legal limits vary. When in doubt, do not drive.