Blood Alcohol Calculator

Estimate blood alcohol concentration based on sex, body weight, drinks consumed, alcohol strength, and time since drinking began. This free blood alcohol calculator shows estimated BAC, common effect ranges, and rough time-to-zero estimates.

Calculate Estimated BAC

Uses a standard-drink estimate and a Widmark-style BAC formula with a basic metabolism adjustment.
Pure alcohol is estimated from drink volume and ABV, then converted into an estimated BAC with time adjustment.
This calculator gives only a rough estimate and should not be used to decide whether it is safe or legal to drive, operate machinery, or make safety-sensitive decisions.
Your result will appear here.

How the blood alcohol calculator works

Alcohol amount:
The calculator estimates pure alcohol from standard drinks or custom drink volume and ABV.

Body weight and sex:
These are used in a Widmark-style estimate to approximate BAC concentration.

Time adjustment:
A basic metabolism rate is applied for the hours since drinking began.

Food adjustment:
A small optional food adjustment can lower the estimate slightly.

Why BAC estimates matter

BAC estimates can help show how quickly alcohol exposure can add up over time. Many people use them for general education and awareness rather than decision-making.

The result should always be treated as a rough estimate, not proof of actual intoxication or safety.

What your result means

Your result shows an estimated BAC, a general effect range, and a rough time-until-zero estimate. It also includes the approximate pure alcohol consumed and the assumptions used.

This gives you a simple educational estimate, not a legal or medical determination.

Blood alcohol calculator tips

Frequently asked questions

Is this BAC calculator exact?

No. It is only a rough estimate and cannot account for every personal or situational factor.

Does eating food stop BAC from rising?

Food can affect absorption timing, but it does not eliminate the alcohol that was consumed.

How fast does BAC go down?

Many basic calculators use an average elimination estimate per hour, but real rates vary.

Can I use this to know if I am okay to drive?

No. You should never use an estimate like this to decide whether to drive or make safety-sensitive choices.