Estimate your BAC from sex, weight, drinks and time using the Widmark formula. Returns g/dL and ‰, predicts sober time, and flags the impairment tier and legal driving limits.
Execution
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Learn when to use this tool, what it supports, and how real users apply it.
Key facts
Category
Health
Input types
select, number
Output type
html
Sample coverage
4
API ready
Yes
Overview
The Blood Alcohol Content (BAC) Estimator calculates your estimated blood alcohol concentration using the Widmark formula based on your sex, body weight, alcohol consumption, and elapsed time. It provides results in both g/dL and permille (‰), estimates the time required to return to a sober state, and flags impairment levels alongside legal driving limits.
When to use
When you want to estimate your blood alcohol concentration after consuming standard drinks or custom beverages over a specific timeframe.
When you need to understand how long it might take for your body to metabolize alcohol and reach a sober state.
When comparing your estimated BAC against common legal driving limits and impairment thresholds for safety awareness.
How it works
1Select your sex and enter your body weight in kilograms or pounds to establish your body water constant.
2Input your alcohol intake by choosing either standard drinks (14g of ethanol each) or entering custom beverage details including volume, ABV, and quantity.
3Specify the hours elapsed since your first drink to account for the body's natural alcohol metabolism rate.
4Submit the details to calculate your current BAC in g/dL and ‰, view your impairment tier, and see the estimated time to sobriety.
Use cases
Estimating personal BAC levels after a social gathering to gauge impairment and understand alcohol clearance times.
Educating individuals on how body weight, sex, and drink strength affect blood alcohol concentration.
Comparing the metabolic differences between consuming standard drinks versus custom high-ABV craft beers.
Examples
1. Estimating BAC for a Male After Standard Drinks
Social Event Attendee
Background
A 75 kg male consumed 3 standard drinks over a period of 2 hours at a dinner.
Problem
He wants to know his estimated BAC and how long it will take to return to a sober level.
How to use
Set the sex to Male, weight to 75 kg, input mode to standard drinks, enter 3 drinks, and set the elapsed time to 2 hours.
Outcome
The tool estimates a BAC of approximately 0.057 g/dL (0.57‰), indicating moderate impairment, and projects about 2.8 hours to reach a BAC of 0.02.
2. Calculating BAC for a Female Consuming Custom Wine Volumes
Responsible Host
Background
A 60 kg female drank 2 glasses of 13% ABV wine, each measuring 150 mL, over the course of 1 hour.
Problem
She needs to calculate her BAC using custom drink volumes rather than standard drink units.
How to use
Set the sex to Female, weight to 60 kg, switch the input mode to custom, enter 13% ABV, 150 mL volume per drink, 2 drinks, and 1 hour elapsed.
Outcome
FAQ
What formula does this calculator use to estimate BAC?
It uses the Widmark formula, which factors in sex, body weight, alcohol dose, and elapsed time to estimate blood alcohol concentration.
What is considered a standard drink in this tool?
A standard drink is defined as containing 14 grams of pure ethanol, which is the standard measure in the United States.
Can I input custom drinks with specific ABV and volume?
Yes, switch the input mode to custom to enter the exact alcohol by volume (ABV) percentage and volume in milliliters.
Does this estimator guarantee I am safe to drive?
No, this tool provides a mathematical estimate for educational purposes only and cannot replace actual breathalyzer or blood tests.
How does the tool calculate alcohol clearance over time?
It applies a standard average alcohol elimination rate of 0.015% (g/dL) per hour from the time of the first drink.
The tool calculates a total of 39g of ethanol consumed, resulting in an estimated BAC of 0.089 g/dL (0.89‰), which is above the US 0.08 legal driving limit.