Quick start
- Open the BAC Calculator.
- Enter drink volume, alcohol by volume, number of drinks, body weight, formula sex, and time since drinking began.
- Use the first example, "Two beers: 2 x 355 mL at 5%", if you want to see a filled-out calculation before entering your own values.
- Calculate, read the formula line, then copy the result only after the units and assumptions look right.
Best uses
Use this guide when one of these tasks matches what you are trying to do.
- Understand how drink count, ABV, body weight, and time affect an estimate.
- Compare different drink sizes and strengths.
- See why BAC estimates are uncertain.
- Avoid using estimates for legal or safety decisions.
What this calculator is for
The BAC Calculator estimates blood alcohol concentration with a Widmark-style formula. It is for education only and must never be used to decide whether to drive.
Use it when you want to: Understand how drink count, ABV, body weight, and time affect an estimate. Compare different drink sizes and strengths.
What to enter
Good answers start with clean inputs. Before calculating, check the labels, units, and dates so the tool is solving the same problem you actually have.
- Enter drink volume, alcohol by volume, number of drinks, body weight, formula sex, and time since drinking began.
- Use actual ABV and pour size where possible, not guesses.
- Remember that mixed drinks can contain more alcohol than one standard drink.
Example walkthrough
Try the calculator example: Two beers: 2 x 355 mL at 5%. The example result is Estimated BAC after time adjustment.
- For two 355 mL beers at 5%, the calculator estimates grams of alcohol first.
- It then applies a body-water factor and subtracts an average elimination amount for elapsed time.
Formula and steps
The calculator estimates grams of alcohol from drink volume and ABV, applies a Widmark-style body-water factor, then subtracts an average elimination rate.
The formula line on the calculator page is there so the answer is not a mystery. Read it when you need to understand where the number came from.
How to read the answer
BAC estimates are especially uncertain because food, medication, drinking speed, tolerance, and body composition can change real-world results. Never use a BAC estimate to decide whether to drive.
- The estimate can be wrong because absorption, food, medications, health, tolerance, and timing vary.
- A lower estimate does not mean safe or legal to drive.
Common mistakes to avoid
Most bad calculator results come from a small input mistake or from using a good estimate for the wrong decision.
- Do not use the result for driving, work, legal, or safety decisions.
- Do not enter the label serving size if your actual pour was larger.
- Do not assume alcohol leaves the body at the same rate for everyone.
What to try next
A related calculator can help check the same topic from another angle instead of relying on one number.
- Plan transportation before drinking.
- Use official public-health guidance for alcohol safety questions.
Sources and safety notes
This guide uses public-health, clinical, or peer-reviewed references where the calculator needs a specific formula or interpretation boundary.
Source links are provided for transparency, but they do not turn the calculator into medical advice or a replacement for professional care.
Examples from the calculator
Estimated BAC after time adjustment
Estimated BAC after time adjustment
Estimated BAC after time adjustment
Common questions
What can I use the BAC Calculator for?
Use it for quick educational estimates, planning, comparison, and trend checks. Health and fitness results should be interpreted with context, not as a diagnosis.
How does the BAC Calculator calculate the result?
The calculator estimates grams of alcohol from drink volume and ABV, applies a Widmark-style body-water factor, then subtracts an average elimination rate.
Is this medical advice?
No. This estimate is not legal, medical, or driving advice. Do not use it to decide whether to drive or perform safety-sensitive tasks.
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History, privacy, and copying
Recent answers stay visible in the page while you work. The history is kept only in the current browser tab and is not sent to a server.
Copy answer copies the expression and result so you can paste it into notes, homework, a message, or another document.