Enter your details below and the number of standard drinks consumed. Select a preset scenario for a quick estimate.

Quick scenarios (sets drinks & hours — still needs your weight)

Body Weight

Standard Drinks Consumed

Not sure? Use our Standard Drink Calculator to convert your pour.

Hours Spent Drinking

Estimates only — not for driving decisions

This tool provides estimates based on an average formula. Actual BAC varies significantly based on food intake, medications, liver function, tolerance, and other individual factors. A result below 0.08% does NOT mean it is safe or legal to drive. Never rely on a calculator to make driving decisions. Always plan ahead: use a designated driver, rideshare, or public transit.

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BAC Effects Reference

General effects at various BAC levels · Individual responses may vary significantly

BAC Level	Status	Typical Effects
0.020–0.039%	Subtle	Slight relaxation, mild mood lift, minimal impairment
0.040–0.059%	Mild	Relaxation, lowered inhibitions, minor motor impairment
0.060–0.079%	Impaired	Judgment and reaction time noticeably affected — driving is dangerous
0.080–0.099%	Over US legal limit	Above the legal driving limit · Significant impairment of balance, speech, vision
0.100–0.149%	Seriously impaired	Slurred speech, poor coordination, memory gaps
0.150–0.199%	Heavily impaired	Nausea, disorientation, loss of motor control
0.200%+	Danger	Risk of blackout, vomiting, respiratory depression — medical emergency possible

These ranges are approximate educational references, not diagnostic thresholds. Effects vary by individual, and BAC estimates may be inaccurate. Impairment and medical emergencies can occur at lower levels. Do not use this chart to determine whether it is safe to drive. The 0.080% row is the limit in most states, in Utah the limit for all drivers is 0.05%.

Frequently Asked Questions

Blood Alcohol Concentration (BAC) is the percentage of alcohol in your bloodstream, expressed as grams of alcohol per deciliter of blood (g/dL). A BAC of 0.08 means 0.08 grams of alcohol per 100 mL of blood. It is the standard measure used in law enforcement and medical settings to assess alcohol intoxication.

In most US states and the District of Columbia, the per se legal BAC limit for driving is 0.08% (0.08 g/dL) for adults 21 and older. Utah is the exception: since 2018 its limit is 0.05% for all drivers. For commercial drivers the limit is 0.04%, and for drivers under 21 most states enforce a zero-tolerance limit of 0.01–0.02%.

This calculator uses the same BAC estimation formula as the CheckUp & Choices app. It combines the number of standard drinks, your body weight, a gender-based factor, and the hours spent drinking, since your body eliminates alcohol over time.

The body eliminates alcohol at roughly 0.015–0.016% BAC per hour, regardless of coffee, food, or exercise. This calculator uses 0.016% per hour as an average, so a 0.12% BAC would take approximately 7–8 hours to reach zero. Only time reduces BAC — there are no shortcuts, and individual rates vary.

Women generally have a higher BAC than men after the same amount of alcohol because they tend to have a lower percentage of body water (which dilutes alcohol) and lower levels of the enzyme that breaks down alcohol in the stomach. The formula reflects this with a different factor for each gender.

Heavier people have more body water, which dilutes alcohol more effectively. For the same number of drinks, a heavier person will have a lower BAC than a lighter person of the same gender.

No. This calculator provides estimates and does not account for individual variability, food intake, medications, tolerance, fatigue, or other factors. Impairment can affect driving ability even below the legal limit. Never use a calculator — or how you feel — to decide whether to drive. Plan ahead: use a designated driver, rideshare, or public transit.

BAC formula used in the CheckUp & Choices app. Legal limit reference: NHTSA. For informational purposes only — not medical or legal advice.

Free BAC Calculator

Curious about your overall drinking habits?

BAC Effects Reference

Frequently Asked Questions

What is BAC (Blood Alcohol Concentration)?

What is the legal BAC limit for driving in the US?

How is BAC calculated?

How long does it take for BAC to return to zero?

Why does gender affect BAC?

Why does weight affect BAC?

Can I use this to decide if it's safe to drive?