Calculator
Enter body weight, drink details, alcohol strength, and elapsed time.
The calculator uses the Widmark method with adjustable options.
Formula Used
This calculator uses a Widmark-style BAC estimate. It first converts drink volume into pure alcohol.
Then it adjusts the result using body weight, body water ratio, drinking time, and burn-off rate.
Pure Alcohol:
Drink Count × Drink Volume in fl oz × ABV ÷ 100 × Absorption Factor
BAC:
(Pure Alcohol × 5.14 ÷ Body Weight in lb ÷ Body Water Ratio) − (Burn-Off Rate × Hours)
Time to Zero:
Estimated BAC ÷ Burn-Off Rate
The result is only an estimate. Food, medicine, fatigue, health, drink strength, and pour size can change actual BAC.
How to Use This Calculator
- Enter your body weight and select the correct unit.
- Select a body water profile or add a custom ratio.
- Enter the number of drinks consumed.
- Add the volume per drink and choose the volume unit.
- Enter the alcohol strength as ABV percentage.
- Add the hours since the first drink.
- Adjust burn-off rate or food factor if needed.
- Press the calculate button to view the result.
- Use CSV or PDF buttons to save the report.
Example Data Table
| Weight |
Profile |
Drinks |
Drink Type |
Time |
Estimated BAC |
| 154 lb |
Typical male |
2 |
12 oz beer, 5% |
2 hours |
0.0249% |
| 120 lb |
Typical female |
3 |
5 oz wine, 12% |
1.5 hours |
0.0943% |
| 200 lb |
Typical male |
4 |
1.5 oz spirits, 40% |
3 hours |
0.0395% |
| 180 lb |
Average |
1 |
5 oz wine, 13% |
1 hour |
0.0115% |
Understanding Weight and BAC
Blood alcohol concentration shows how much alcohol may be present in the bloodstream.
Body weight is a major part of the estimate. A heavier person usually has more body water.
That water can dilute alcohol more than a lighter body can. This is why the same drink count
can give different BAC values for different people.
Why the Estimate Changes
The calculator uses weight, drink size, alcohol strength, time, and body water ratio.
It converts each drink into pure alcohol ounces. Then it applies the Widmark method.
The result is reduced by an average burn-off rate over time. This makes the output more useful
than a simple drink counter. It also shows why speed matters. Drinking quickly can raise BAC
before the body removes much alcohol.
Important Limits
BAC calculators are only estimates. Real results can change because of food, medicines, fatigue,
health, age, hydration, and measuring errors. Drink recipes also vary. A heavy pour can contain
much more alcohol than expected. Because of these limits, this tool should not be used to decide
whether driving is safe. The safest choice after drinking is to avoid driving completely.
Practical Use
Use the calculator before planning transport, events, or personal safety steps. Try several drink
counts and time values. Compare how weight changes the estimate. The result card shows the
estimated BAC, grams per deciliter, alcohol consumed, and a basic interpretation. You can download
the result as a CSV file or a PDF report for records.
Safer Planning
The best value of this tool is education. It helps users see patterns before risky choices happen.
A small body weight, high alcohol percentage, large serving size, or short drinking period can
change the estimate quickly. Always follow local law, medical advice, and common sense. When unsure,
choose water, food, rest, and a safe ride. Personal safety matters more than any calculated number.
Reading Results
A lower result does not prove clear judgment. A higher result signals stronger concern. Use the color
hint only as guidance. The table gives sample outcomes, so users can compare common weights and drink
patterns before entering their own details for safer planning today.
FAQs
What does BAC mean?
BAC means blood alcohol concentration. It estimates the amount of alcohol in blood. A higher BAC usually means stronger impairment and greater safety risk.
How does body weight affect BAC?
Body weight changes alcohol dilution. A heavier body usually has more water volume, so the same alcohol amount may produce a lower estimate.
Is this calculator legally reliable?
No. It is an educational estimate only. Legal BAC can only be measured with approved testing methods used by qualified authorities.
Can food lower my BAC?
Food may slow absorption, but it does not remove alcohol instantly. The calculator includes a simple absorption adjustment for planning only.
What is a standard drink?
In this calculator, one standard drink equals about 0.6 fluid ounces of pure alcohol. Actual serving sizes can vary a lot.
Why is burn-off rate adjustable?
People process alcohol at different speeds. The default is a common estimate, but the setting lets advanced users compare different assumptions.
Can I use the result before driving?
No. Do not use this result to decide if driving is safe. The safest choice after drinking is not to drive.
Why does the same drink give different results?
Weight, body water ratio, drink size, alcohol strength, time, and absorption can all change the estimated BAC value.