Calculate alcohol burn-off time, estimate BAC from drinks, or measure BAC drop rate using your readings, drink amount, weight, and time.

Educational estimate only. Do not use this result to decide when to drive or operate machinery. BAC can still rise after drinking; individual absorption and elimination vary.

% BAC means grams per deciliter; g/L is numerically equivalent to per mille.

% BAC means grams per deciliter; g/L is numerically equivalent to per mille.

Default 0.015 percentage points per hour is an illustrative average, not your measured rate.

Alcohol Burn Off Rate Formula

The calculator uses one of three formulas depending on the calculation you choose.

Time to target:

t = max(0, BACcurrent - BACₜarget) / r

Estimate from drinks (Widmark):

BACₚeak = (A / (rw × W)) × 100 BACₙow = max(0, BACₚeak - r × h)

Measured rate:

r = (BAC₁ - BAC₂) / t
  • BAC_current, BAC_target, BAC_1, BAC_2 — blood alcohol concentration in % (g/dL)
  • r — burn-off (elimination) rate in % per hour
  • t, h — elapsed time in hours
  • A — total alcohol consumed in grams (volume_mL × ABV/100 × 0.789)
  • W — body weight in grams
  • r_w — Widmark body water factor (≈0.68 male, ≈0.55 female)

These formulas assume the alcohol has been fully absorbed and that elimination follows zero-order kinetics. Actual BAC depends on food intake, drinking pace, medications, and individual metabolism, so treat the output as an estimate, not a legal or medical figure.

Reference Values

Elimination varies by person. These are illustrative rates, not a way to infer an individual rate from drinking history.

Drinker type Rate (%/hr) Notes
Slow metabolizer0.010Slower illustrative assumption
Average adult0.015Most common default
Fast metabolizer0.020Faster illustrative assumption; tolerance does not establish elimination rate
Heavy chronic drinker0.025–0.030Reported in some studies

Illustrative fully absorbed estimates for a 160 lb adult using distribution factor 0.68 and elimination rate 0.015% BAC/hour; these are not safe-to-drive times:

Drink Approx. BAC bump (160 lb) Time to clear
12 oz beer (5%)~0.028%~1 hr 54 min
5 oz wine (12%)~0.028%~1 hr 54 min
1.5 oz shot (40%)~0.028%~1 hr 54 min
Three drinks in a row~0.085%~5 hr 40 min

Example and FAQ

Example: Your BAC is 0.080% and you want to reach 0.000%. At an average rate of 0.015%/hr, you need 0.080 ÷ 0.015 = 5.33 hours, or about 5 hr 20 min.

Does coffee or food speed it up? Coffee does not make someone sober. Food can affect absorption and metabolism, but neither food nor coffee provides a reliable way to calculate a safe-to-drive time.

Why does the calculator sometimes show a higher BAC than I expected? The drink estimate uses a simplified Widmark model and subtracts assumed elimination. It is not a real-time measurement. Recently consumed alcohol may still be absorbing, so actual BAC can continue rising after the last drink.

Can I drive when the calculator says I am at 0.00%? No. This calculator cannot establish that you are sober or safe to drive, even when its modeled BAC is zero. Arrange a sober driver or another safe way home.

Why does my measured rate look unusual? Measurement uncertainty and ongoing absorption affect the difference between readings. A longer interval does not make this a reliable personal elimination rate or driving test.