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BAC Calculator
Widmark blood-alcohol estimate + time-to-sober + per-state DUI limits — an estimate only, never a clearance to drive. Accurate, instant and free — for United States.
What these mean:
What these mean:
Estimated BAC 0.046% — under California's 0.08% adult limit. This is an estimate; never use it to decide whether to drive.
Rates as of 2026Estimate only — never use this to decide whether to drive
Estimated BAC
0.046%
Under the California 0.08% adult limit — but not necessarily safe to drive. Impairment begins well below any limit.
Hours to under limit
0 hrs
Hours to ~0
3 hrs
California adult limit
0.08%
The same drinks produce a higher BAC in women
How we calculate this
Reviewed by Reckonist Editorial · Last reviewed July 2026. Figures follow the methods and sources set out in our editorial standards.
Widmark estimate (r 0.68 male / 0.55 female, elimination ~0.015%/hr, US standard drink 14 g). Per-state limits as of 2026. This is general safety information, not medical or legal advice, and not a determination of fitness to drive.
Widmark · NHTSA/CDC · limits as of 2026
Estimate only — never use this to decide whether to drive
How the Widmark BAC estimate works
Blood alcohol concentration (BAC) is estimated with the Widmark equation from four inputs: the alcohol consumed (in standard drinks), your body weight, your sex (which sets the body-water fraction r), and the time since your first drink. Alcohol is then subtracted at the average elimination rate of about 0.015% per hour.
Widmark BAC
drinks + weight + sex + time → BAC%
BAC% = (A_g / (W_g × r)) × 100 − 0.015 × t
r = 0.68 men / 0.55 women (body-water fraction). A_g = drinks × 14 g. W_g = weight in grams.
Time-to-sober
hours until BAC falls to a target
hours = (BAC − target) / 0.015
Nothing speeds this up — not coffee, food or a cold shower. Only time lowers BAC.
Each of these contains about 14 grams of pure alcohol — one standard drink. Cocktails, craft beers and generous pours often hold more than one, so it is easy to underestimate your intake.
- 1Man, 180 lb, 3 drinks, 2 h: A = 42 g, W = 81,646 g, r = 0.68 → (42 / (81,646 × 0.68)) × 100 = 0.076 − 0.03 ≈ 0.046% — under 0.08 but over the 0.04 commercial limit.
- 2Woman, 140 lb, same drinks: r = 0.55 → (42 / (63,503 × 0.55)) × 100 = 0.120 − 0.03 ≈ 0.090% — over 0.08, from the same drinks.
Per-state DUI limits — and why 'under' isn't 'safe'
The adult per-se limit is 0.08% in every US state except Utah, which is 0.05% (lowered December 2018 — the only state at 0.05). Commercial drivers face 0.04%, and drivers under 21 face zero-tolerance limits of 0.02% or lower. Select your state above to compare your estimate against its adult limit.
'Under the limit' is not a green light
Widmark is an approximation — accuracy means saying so
The most accurate thing a BAC calculator can do is be honest about what it cannot know. Widmark assumes a simple average body-water fraction and a fixed elimination rate. In reality, an empty versus full stomach, drinking pace, medications, hydration, liver health, hormones and individual metabolism all shift real BAC materially. BAC also peaks after your last sip, not immediately — so a low early number can still rise. Treat every figure here as a rough estimate.
The only accurate reading is a test
Frequently asked questions
This tool uses the Widmark equation: BAC% = (alcohol in grams ÷ (body weight in grams × r)) × 100 − 0.015 × hours, where r is the body-water fraction (0.68 for men, 0.55 for women) and 0.015 %/hr is the average elimination rate. For example, a 180 lb man who has had 3 standard drinks (42 g of alcohol) over 2 hours estimates to about 0.046%. It is an estimate, not a measurement — only a breath or blood test measures actual BAC.
In the US, one standard drink contains 14 grams of pure alcohol (CDC). That is roughly 12 oz of regular beer at 5% ABV, 5 oz of wine at 12% ABV, or 1.5 oz of distilled spirits at 40% ABV (a shot). Cocktails, craft beers and large pours often contain more than one standard drink, which is why people routinely underestimate how much they have had.
The adult per-se DUI limit is 0.08% in every US state except Utah, which lowered it to 0.05% in December 2018. Commercial drivers are held to 0.04%, and drivers under 21 face zero-tolerance limits of 0.02% or lower. Being "under the limit" does not mean you are safe or legal to drive — you can still be charged with impaired driving below the per-se limit.
Alcohol leaves the body at roughly 0.015% per hour, and nothing reliably speeds it up — not coffee, cold showers, food or water. Hours to reach a target = (current BAC − target) ÷ 0.015. From 0.09%, dropping under the 0.08% limit takes about 0.7 hours, and reaching roughly zero takes about 6 hours. Because BAC keeps falling only at this fixed rate, the only safe plan after drinking is time plus not driving.
The Widmark body-water fraction r is lower for women (0.55) than men (0.68) on average, because women tend to have a higher proportion of body fat and less body water to dilute the alcohol. So the same number of drinks at the same body weight produces a higher estimated BAC in women. This is a population average; individual physiology, hormones and medications vary.
The most accurate thing any Widmark calculator can do is be honest about its limits. Widmark is an approximation: an empty versus full stomach, medications, hydration, drinking pace, health conditions and individual metabolism all shift real BAC materially. This tool shows a careful estimate and states those caveats plainly — it does not fake false precision. The only accurate reading of your actual BAC is a breathalyzer or blood test.
No. This is an estimate for general education only and is not a legal defense. Back-calculating BAC to an earlier point in time (retrograde extrapolation) is disputed and heavily contested in court. Never drive based on this number, and consult a qualified attorney for any legal matter.
Method, standards & references
Methodology: BAC% = (A_g / (W_g × r)) × 100 − 0.015 × t (Widmark); r = 0.68 men / 0.55 women; elimination ≈ 0.015 %/hr; US standard drink = 14 g. Time-to-target = (BAC − target) / 0.015. Per-state adult limits are 0.08% (Utah 0.05%), commercial 0.04%, under-21 0.02%, held in versioned config and re-verified on law change. All calculations run client-side and nothing is stored. Reference limits as of 2026. Estimate only — not a determination of fitness to drive, and not a legal defense.
Cross-links
How we calculate this
Reviewed by Reckonist Editorial · Last reviewed July 2026. Figures follow the methods and sources set out in our editorial standards.
BAC is estimated with the Widmark formula (r 0.68 male / 0.55 female, elimination ~0.015%/hr, US standard drink 14 g); per-state limits as of 2026. This is general safety information for education, not medical or legal advice, not a legal defense, and not a determination of whether you are fit to drive. Impairment begins below any legal limit — if you have been drinking, do not drive.
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