Start with pure alcohol
Serving size × ABV × ethanol density tells you how much pure alcohol a drink contains. What does ABV mean? →
ALCOHOL INFORMATION TOOLS
BAC Calculator.
Blood alcohol estimate, with clear limits.
Use this educational blood alcohol calculator to estimate BAC from your drinks, body weight, and elapsed time. Every result explains its limits—an estimate is never a decision to drive.
Start your BAC calculationCORE TOOL
BAC Calculator: estimate blood alcohol concentration
Estimate blood alcohol concentration from the drinks you actually had—not a blank “amount of alcohol” field.
MORE USEFUL TOOLS
Start with the number you know
Standard drinks & alcohol units
Convert any serving and ABV into the units used where you live.
Open calculator →Alcohol calories
See alcohol-only calories alongside pure alcohol and standard drinks.
Calculate calories →Standard drinks per container
Check the alcohol in a full bottle, can, pint, or other container.
Calculate a container →BAC Calculator over time
See how a Widmark-style BAC estimate changes across future hours.
See the timeline →BAC chart & uncertainty
Explore a model timeline and why an online BAC estimate is never a measurement.
Explore the chart →BAC unit conversion
Convert a BAC percentage into g/dL, mg/dL, g/L, and mg per 100 mL.
Convert BAC units →Australia standard drinks
Use Australia’s 10 g standard-drink reference and read common labels.
Read the Australia guide →ABV to proof
Convert US-style proof and alcohol by volume from the label.
Convert ABV and proof →Alcohol grams
Find pure alcohol grams, reference units, and alcohol-only calories.
Calculate grams →Cocktail alcohol
Add up to three alcoholic ingredients in a cocktail recipe.
Calculate a cocktail →Compare drink strength
Compare two labels by container size, ABV, pure alcohol and local reference units.
Compare two labels →UK alcohol units
Calculate units from a product's volume and ABV.
Calculate UK units →U.S. standard drinks
Use the U.S. 14 g reference and calculate from a product label.
Read the U.S. guide →Party drink checklist
Build an inclusive beverage checklist with water and alcohol-free options.
Plan an event →Alcohol spending
Use your own purchase assumptions to view weekly, monthly and annual spending.
Estimate spending →KNOW THE BASICS
A drink is not always one standard drink.
Units change by country
One U.S. standard drink contains 14 g of pure alcohol. The UK and Australia use different definitions. See the country guide →
Time is the only reducer
Coffee, water, food, and cold showers may change how you feel, but they do not reliably lower BAC faster. What is BAC? →
Check the full bottle
Wine strength changes the total alcohol in a bottle. Wine bottle examples →
Beer is not one fixed amount
Container size and ABV both change the answer. Beer examples →
Know the limits of BAC estimates
A BAC tool estimates; it cannot measure or clear someone to drive. BAC levels explained →
Compare countries
The same alcohol amount produces different reference units around the world. Compare country units →
CLEAR ANSWERS
Before you rely on a number.
Can a blood alcohol calculator tell me whether I can drive?
No. This is an educational estimate, not a breath test or a legal or medical assessment. The NHTSA explains that it is difficult to assess your own BAC or impairment. If you have been drinking, arrange a sober ride instead. Learn what BAC means.
Why does this blood alcohol calculator show a range?
Food, timing, drink size, body composition, health conditions, medication, absorption, and individual metabolism can all change actual BAC. A breath or blood test is needed to measure it. See our assumptions and limits.
How accurate is an online BAC calculator?
An online BAC calculator can show the arithmetic of an estimate, but it cannot accurately determine an individual's actual BAC. It cannot know every drink's timing, absorption, health context, medication, or metabolism. Treat the result as educational context, not a breath test, legal opinion, or reason to drive. Learn how BAC is measured.
Is a 12 fl oz beer always one standard drink?
No. Alcohol amount depends on serving size and ABV. A 12 fl oz beer at 5% ABV is about one U.S. standard drink, while a stronger beer can contain more. See country definitions and examples.
What is the difference between a standard drink and a serving?
A serving is the amount poured or sold. A standard drink is a country-specific reference amount of pure alcohol, so one serving can contain less than, equal to, or more than one standard drink.
TRANSPARENT BY DESIGN
A calculator should show its work.
Our BAC estimate uses a Widmark-style calculation based on total pure alcohol, body weight, sex used in the formula, and elapsed time. We show a range because a person’s real BAC cannot be accurately determined from an online form.
Read the method and limits