Georgia BAC Calculator: Estimate Your Blood Alcohol Level
Enter your drinks, body weight and time to estimate your blood alcohol content (BAC) — then see exactly how Georgia law treats that number: license suspension, jail exposure, and the defenses that apply at each level.
This calculator is built for people trying to understand a DUI stop or arrest after the fact. It is an estimate, not a breathalyzer. Never use it to decide whether you are safe to drive — if you have been drinking, get a ride.
How the BAC Calculator Works
The calculator uses the Widmark formula, the same equation forensic toxicologists use when they estimate a driver’s BAC in court:
BAC = (grams of alcohol ÷ (body weight in grams × r)) × 100 − (0.015 × hours)
- Grams of alcohol: each US standard drink contains about 14 grams of pure alcohol.
- r (body-water constant): about 0.68 for men and 0.55 for women. Alcohol spreads through body water, so the same drinks produce a higher BAC in a smaller body or one with less water.
- 0.015 per hour: the average rate your liver removes alcohol. Some people eliminate faster or slower.
Example: a 170-pound man who has four standard drinks over two hours has an estimated BAC of about .077 — just under Georgia’s .08 limit. One more drink in that same window pushes the estimate to about .10.
What Counts as One Standard Drink?
Most people undercount because modern pours are bigger and stronger than the “standard” drink the formula assumes. Use this table to convert what you actually had:
| What you drank | Standard drinks |
|---|---|
| 12 oz regular beer (5%) | 1 |
| 16 oz pint of regular beer (5%) | about 1.3 |
| 12 oz craft IPA (8%) | about 1.6 |
| 5 oz glass of wine (12%) | 1 |
| 9 oz restaurant wine pour (12%) | about 1.8 |
| 1.5 oz shot of liquor (80 proof) | 1 |
| Margarita, Long Island or other mixed cocktail | often 2 or more |
Georgia BAC Limits
Once you have an estimate, the number that matters depends on who you are and what you were driving. Georgia’s thresholds under OCGA § 40-6-391:
| Driver | Limit |
|---|---|
| Drivers 21 and older | 0.08% |
| Drivers under 21 | 0.02% — a single drink can exceed it |
| Commercial drivers (CDL) in a commercial vehicle | 0.04% |
| Enhanced “high BAC” penalties | 0.15% and above |
| DUI “Less Safe” | Any BAC if the officer claims impairment |
For a full breakdown of what each threshold triggers, see our Georgia BAC limit guide.
Why Your Real BAC Can Differ From the Estimate
The Widmark formula assumes every drink has been fully absorbed. Real bodies are messier:
- Food: a full meal slows absorption and can lower your peak BAC substantially.
- Drinking pace: alcohol keeps absorbing for 30 to 90 minutes after your last drink, so BAC can still be rising when you are pulled over — and higher at the station than it was behind the wheel.
- Body composition: two people with the same weight can have very different body-water percentages.
- Medications and health conditions: some affect how quickly alcohol is absorbed or eliminated.
Why the Breath Test Can Differ From Your Real BAC
The number on a Georgia DUI arrest report comes from the Intoxilyzer 9000 breath machine or a blood draw — and both can be wrong. The most common problems Attorney Blevins looks for:
- The 20-minute observation period. The officer must watch you continuously before the test to rule out burping, vomiting or mouth alcohol. Skipped or interrupted observation can taint the result.
- Calibration and maintenance records. Every Intoxilyzer must be inspected and certified on schedule. Gaps in the logs can make the result inadmissible.
- Rising BAC. A test an hour after driving can show a number above what you actually had while driving.
- Medical and dietary interference. Acid reflux (GERD), diabetes and ketogenic diets can inflate breath readings.
- Blood-test chain of custody. Blood samples must be drawn, stored and tested correctly, with documented handling at every step.
For the technical detail behind each of these, read how BAC evidence is challenged in Georgia DUI cases.
Already Arrested? Two Things Matter Right Now
1. Your license deadline. In Georgia you have 30 days from the date of arrest to request an administrative license suspension (ALS) hearing. Miss it and your license is suspended automatically. Use the Save My License deadline calculator to see your exact date.
2. The evidence. Dash-cam and body-cam footage, breath-machine records and 911 audio can be overwritten or lost if nobody requests them early. The sooner an attorney is involved, the more of it can be preserved.
Call Attorney Richard Blevins at (770) 419-1945 for a free, confidential case evaluation — or use the case evaluation form in the sidebar.
Frequently Asked Questions
How many drinks put you over .08 in Georgia?
It depends on your weight, sex and how fast you drank. As a rough guide, a 170-pound man reaches about .09 after four standard drinks in one hour, and a 140-pound woman can pass .08 after two to three. Bigger pours and stronger beers get you there faster. For drivers under 21 the limit is .02, which a single drink can exceed.
How accurate are online BAC calculators?
They give a reasonable ballpark, not a precise number. The Widmark formula assumes full absorption and an average elimination rate, so food, drinking pace, body composition and medications can move your real BAC well above or below the estimate. That same uncertainty is why timing and absorption arguments matter when challenging a breath or blood test.
How long does it take for BAC to go down?
On average your body removes about .015 BAC per hour — roughly one standard drink per hour. Coffee, cold showers and food after the fact do not speed it up. If you reach .12, it can take about eight hours to return to zero.
Can I be charged with DUI in Georgia if my BAC is under .08?
Yes. Georgia’s DUI “Less Safe” law allows a charge at any BAC if the officer believes alcohol made you less safe to drive. These cases rely heavily on the officer’s observations and field sobriety tests, which makes them some of the most defensible DUI cases.
Can I use a BAC calculator to decide whether I am safe to drive?
No. An estimate can be off in either direction, impairment starts well below .08, and you can be charged at any BAC. The only safe choice after drinking is not to drive. This tool is meant to help you understand a stop or arrest that has already happened.
