Enter the total change in BAC and the total time (hrs) into the Alcohol Burn Off Rate Calculator. The calculator will evaluate the Alcohol Burn Off Rate.
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Alcohol Burn Off Rate Formula
The calculator uses one of three formulas depending on the tab you choose.
Time to target:
t = (BAC_current - BAC_target) / r
Estimate from drinks (Widmark):
BAC_peak = (A / (r_w * W)) * 100 BAC_now = BAC_peak - r * h
Measured rate:
r = (BAC_1 - BAC_2) / 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 × 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
Burn-off rate varies by person. The ranges below are typical for healthy adults.
| Drinker type | Rate (%/hr) | Notes |
|---|---|---|
| Slow metabolizer | 0.010 | Light or occasional drinker |
| Average adult | 0.015 | Most common default |
| Fast metabolizer | 0.020 | Frequent drinker, higher tolerance |
| Heavy chronic drinker | 0.025–0.030 | Reported in some studies |
How long it takes a typical drink to clear at 0.015%/hr, ignoring tolerance and food effects:
| Drink | Approx. BAC bump (160 lb) | Time to clear |
|---|---|---|
| 12 oz beer (5%) | ~0.025% | ~1 hr 40 min |
| 5 oz wine (12%) | ~0.025% | ~1 hr 40 min |
| 1.5 oz shot (40%) | ~0.025% | ~1 hr 40 min |
| Three drinks in a row | ~0.075% | ~5 hr |
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? No. Once alcohol is in your bloodstream, only time lowers BAC. Food slows absorption before drinking; it does not raise the burn-off rate.
Why does the calculator sometimes show a higher BAC than I expected? The drinks tab estimates peak BAC using the Widmark formula, then subtracts what should have burned off. Recently consumed drinks may not be fully absorbed yet, so real-time BAC can keep climbing for 30 to 90 minutes after the last drink.
Can I drive when the calculator says I am at 0.00%? Treat the result as a rough estimate. If you have any doubt, do not drive. Legal limits and personal impairment do not always line up.
Why does my measured rate look unusual? Short gaps between readings amplify breathalyzer error. Use at least one hour between readings for a more reliable rate.
