Health

Blood Alcohol Calculator

Estimate blood alcohol content by weight, drink count, ABV, and hours since drinking started.

Widmark estimateBAC over timeSafety reference

Result // Widmark estimate

Blood alcohol snapshot

Estimate only

Current BAC

0.040%

Computed at the selected elapsed time.

Time to 0.00%

2.7 h

Clear around hour 4.7 since drinking started.

Pure alcohol

1.8 oz

42.0 g in the drink total.

Estimate only

This is a rough estimate. It does not replace legal, medical, or safety judgment.

Hourly timeline

The estimate steps forward in one-hour increments and ends on the first zero row.

Clear around 4.7 h

PointEstimated BAC
Now0.040%
+1 h0.025%
+2 h0.010%
Clear0.000%

Need a change for Blood Alcohol Calculator?

About this calculator

Method, formulas, and limits.

What this does

Estimates blood alcohol content (BAC) based on body weight, the number and type of drinks consumed, the alcohol percentage of each drink, and the time elapsed since drinking started. It also shows how the estimate declines over time as the body metabolizes alcohol.

Who it is for

For anyone looking for a general educational reference on how alcohol consumption affects estimated BAC. It is not intended for legal, medical, or driving decisions.

How it works

The calculator uses a Widmark-style formula that estimates body water from weight and sex, divides pure alcohol by that volume, and subtracts an average elimination rate for the elapsed time.

Limitations

This is an estimate only. Actual BAC varies with metabolism, food, medications, hydration, health conditions, and many other factors. Never use it to decide whether you can drive or for a legal or medical purpose.

Key calculations

Total alcohol consumed
totalAlcohol = drink volume × ABV × 0.789, with 0.789 converting milliliters of ethanol to grams.
Widmark BAC estimate
bac = total alcohol / (weight × distribution ratio × 10), then subtract metabolism.
BAC over time
currentBAC = initialBAC − (0.015 × hours elapsed). The typical elimination rate is 0.015 BAC per hour.

Reference ranges

Mild impairment
0.02–0.05% BAC. Some loss of judgment and relaxation. Below the legal limit in all US states.
Legal-limit boundary
0.05–0.08% BAC. Impairment increases. 0.08% is the standard legal driving limit in most US states.
Significant impairment
0.08–0.15% BAC. Poor coordination, slower reaction time, and reduced judgment. Driving can have legal consequences.
Severe intoxication
0.15% BAC and above. High risk of blackout, vomiting, and alcohol poisoning. Emergency medical attention may be needed.

How to use it

  1. 1.Select your sexChoose male or female. The Widmark estimate uses a different distribution ratio for each option.
  2. 2.Add drinksEnter the number of drinks, the volume per drink, and the alcohol by volume (ABV) percentage.
  3. 3.Set elapsed timeEnter how many hours have passed since drinking started. The calculator subtracts metabolized alcohol.
  4. 4.Review the estimateReview the estimated BAC, time to zero, and the hourly timeline as the estimate declines.

The calculator estimates body water from weight and sex, divides the total alcohol consumed by that volume, and subtracts an average metabolic elimination rate multiplied by elapsed hours. The result is a rough BAC percentage, not a measurement.

Actual BAC varies with metabolism, food, medication, hydration, health, and many other factors. Two people with the same weight and drink count can have very different BAC levels.

No. This calculator is an educational reference only and must never be used to determine fitness to drive or for a legal or medical purpose. If you have been drinking, arrange alternate transportation.

Food, liver health, medications, fatigue, carbonation, and genetic differences can affect how quickly alcohol enters and leaves the body. This simple model cannot account for those differences.

The estimate uses an average elimination rate of about 0.015 BAC per hour, but the rate varies by person. Coffee, cold showers, and exercise do not speed up alcohol metabolism; time is the reliable factor.

Yes. The Widmark estimate uses different distribution ratios for male and female inputs. Food is not modeled, but it can slow absorption and change peak BAC.

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