BAC by Weight Calculator
Estimate BAC from body weight, drink count, drink type, and elapsed time.
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Result
Enter values above and click Calculate to see your result.
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Formula
How it works: The calculator estimates alcohol concentration from standard drinks and subtracts alcohol metabolized over time.
Worked Example
How Body Weight Affects Blood Alcohol Content
Body weight is one of the most significant factors in BAC estimation. Heavier individuals have more body water to dilute alcohol, resulting in a lower BAC from the same number of drinks.
- The Widmark formula distributes alcohol across total body water, which increases with body weight
- A 120-pound person drinking 3 beers will have a significantly higher estimated BAC than a 220-pound person drinking the same amount
- Gender affects the body water ratio: males average about 68% body water while females average about 55%, which is why the same weight does not produce the same BAC
- This calculator is for educational purposes only and should never be used to make driving or safety decisions
Individual metabolism, food intake, hydration, and medications all affect real BAC. Professional breathalyzer or blood tests are the only reliable measurements.
You can also calculate changes using our BAC Calculator, Sober Time Calculator, Drinks to BAC Calculator, Gender BAC Calculator or Alcohol Metabolism Calculator.
Frequently Asked Questions
Is this legal or medical advice?
No. This is a simplified educational estimate. Never use any calculator to make decisions about driving, operating machinery, or safety.
Why is this only an estimate?
Actual BAC varies due to metabolism speed, food in the stomach, hydration levels, medications, liver health, and many other individual biological factors that a calculator cannot account for.
Why does body weight matter so much for BAC?
Alcohol distributes through body water. Heavier people have more body water to dilute the alcohol, producing a lower concentration (BAC) from the same number of drinks.
Does the type of drink change the result?
Yes. Different drink types contain different amounts of pure alcohol. A standard beer (12 oz, 5%), wine (5 oz, 12%), and spirits (1.5 oz, 40%) each contain roughly 14 grams of alcohol, but actual amounts vary by brand and pour size.
Is it possible to embed the BAC by Weight Calculator on another website?
Yes, embedding the BAC by Weight Calculator is free. Hit the "Embed" button on this page, adjust the width, height, and theme, then grab the iframe code. It works on WordPress, Wix, Squarespace, Shopify, and plain HTML pages. No registration needed. Full instructions at calculory.com/services/embed-calculators.
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