Calculate Your BAC Quickly
Written by The Kalcule Team
Estimate your blood alcohol content (BAC) with our calculator. Track your alcohol consumption and understand how different drinks affect your BAC levels.
Why BAC Matters
Understanding your blood alcohol content is crucial for making informed decisions about drinking and driving. BAC levels affect your judgment, coordination, and reaction time, making it essential to monitor your alcohol consumption.
How to Use the BAC Calculator
- 1Enter your gender and body weight
- 2Input the number and types of drinks consumed
- 3Specify the time elapsed since your first drink
- 4Get your estimated BAC and time until sober
Tips for Safe Drinking
Eat before and while drinking, pace yourself with water between drinks, and always plan for safe transportation. Remember that BAC calculators are estimates and should not be used to determine if you're safe to drive.
Frequently Asked Questions
Find answers to common questions about blood alcohol content (BAC), alcohol metabolism, and how various factors like weight, gender, and time affect your BAC levels. Learn about safe drinking practices and the limitations of BAC calculations.
BAC calculators provide estimates based on general factors. Individual metabolism, food consumption, medications, and other variables can affect actual BAC levels. Never rely solely on calculators to determine if you're safe to drive.
On average, the body eliminates alcohol at a rate of about 0.015% per hour. However, this rate varies by individual and circumstances. The only way to be certain you are completely sober is to allow enough time to pass without drinking.
No. Never. The Widmark estimate ignores gastric emptying, recent food, medication, illness, drinking pattern and individual metabolism. If you have been drinking, do not drive. Use a designated driver, taxi or public transport.
Erik Widmark’s equation estimates blood alcohol from alcohol dose, body weight and a sex-specific volume-of-distribution factor, minus an elimination rate over time. It is a forensic approximation, not a breathalyser.
Body size, sex-specific water fraction, time since drinks and number of drinks all change the result. Even then, real blood concentrations scatter around the estimate.
A commonly used average is about 0.015% per hour, with a wide individual range. Coffee, cold showers and “sober up” myths do not speed liver metabolism.
Food, especially with fat and protein, slows absorption so the peak is later and often lower. It does not cancel the alcohol already absorbed.
No. Limits differ by country and by driver category (for example learners). This site does not give legal advice. Check the law where you are.
Many medicines interact with alcohol or increase impairment even at a low BAC. That interaction will not show up in this formula. Ask a pharmacist or clinician.
A properly calibrated device measures what is in your breath now. This calculator guesses from inputs you type. Neither is a licence to drive after drinking.
Still have questions?
If you couldn't find the answer you were looking for, please contact our support team for personalized assistance.
Stay Safe and Responsible
Use this calculator as an educational tool to understand how different factors affect your BAC. Always err on the side of caution and never drink and drive. If you plan to drink, arrange for safe transportation in advance.
What Widmark can and cannot do
The Widmark equation estimates concentration from dose, body mass and a distribution factor, then subtracts elimination over time. Real measurements scatter around that line because absorption, food, sex-specific water fraction and liver rate all vary.
This page will never tell you that you are fit to drive. Impairment starts below many legal limits, and the estimate can be wrong in either direction. If you drank, do not drive.
Time is the only sobering agent
Caffeine, exercise and cold water change how awake you feel, not how fast the liver clears ethanol. Plan transport before the first drink. Related reading: alcohol effects, sober-up myths, how to calculate a drink and addiction resources — none of them replace professional help.
Formula source: Widmark formula — Widmark E.M.P. (1932)