Blood Alcohol Calculator Examples: Weights & Drink Counts

July 15, 2026

Every number below is a population-average estimate for a hypothetical person, not a measurement of any real individual. None of these examples are a driving-safety threshold — regardless of the result, the only safe choice after any alcohol is not to drive.

Three worked examples using the same Widmark formula the blood alcohol level calculator runs. For term definitions, see the BAC terms glossary.

Example 1 — 140 lb Woman, 3 Standard Drinks, 2 Hours Elapsed

Alcohol consumed = 3 drinks × 14 g = 42 g
Body weight       = 140 lb × 453.592 g/lb = 63,502.9 g
r (women)         = 0.55

Raw BAC = (42 × 100) ÷ (63,502.9 × 0.55) = 0.120%
Elimination = 0.015%/hour × 2 hours = 0.030%
Estimated BAC = 0.120% − 0.030% = 0.090%

This estimate sits above the common 0.08% standard reference threshold — but the point of showing that isn’t to establish a target to stay under. The estimate itself is a rough figure, and impairment to reaction time and judgment can be present well below any legal threshold regardless of the exact number.

Example 2 — 220 lb Man, 4 Standard Drinks, 3 Hours Elapsed

Alcohol consumed = 4 drinks × 14 g = 56 g
Body weight       = 220 lb × 453.592 g/lb = 99,790.2 g
r (men)           = 0.68

Raw BAC = (56 × 100) ÷ (99,790.2 × 0.68) = 0.083%
Elimination = 0.015%/hour × 3 hours = 0.045%
Estimated BAC = 0.083% − 0.045% = 0.038%

Even at an estimate below the standard 0.08% threshold, this figure would still exceed the 0.04% commercial (CDL) limit and any zero-tolerance underage limit — see BAC calculator and legal limits by context for how these thresholds differ by driver category.

Example 3 — 160 lb Woman, Two Mixed-Drink Shots, 30 Minutes Elapsed

Alcohol consumed = 2 × (1.5 oz, 80-proof/40% ABV) ≈ 2 × 14 g = 28 g
Body weight        = 160 lb × 453.592 g/lb = 72,574.7 g
r (women)           = 0.55

Raw BAC = (28 × 100) ÷ (72,574.7 × 0.55) = 0.070%
Elimination = 0.015%/hour × 0.5 hours = 0.0075%
Estimated BAC = 0.070% − 0.0075% ≈ 0.063%

Only 30 minutes have passed in this example, and absorption may not even be complete yet in reality — meaning the actual BAC at this moment could still be rising, not falling, even though the elimination term in the formula has already started subtracting. This is exactly why a Widmark estimate taken shortly after drinking is especially unreliable — see how long alcohol stays in your system for why absorption timing matters so much.

What These Examples Actually Show

Small differences in weight, sex, drink count, and elapsed time move the estimate substantially — which is exactly why no single “rule of thumb” (like “one drink per hour”) reliably predicts a real person’s BAC. See common misconceptions about blood alcohol estimates for the specific myths that lead people to trust an estimate like these more than they should.

Regardless of what any of these examples calculate: if you’ve had any alcohol, the only safe choice is not to drive. Use a rideshare, a taxi, public transit, or a sober driver.