BAC Calculator
How the Widmark Formula Works
Calculating your Blood Alcohol Content (BAC) isn't just a guess; it's chemistry. This calculator uses the Widmark Formula, developed by Swedish physician Erik Widmark. It is still used by forensic scientists and courts today.
The formula considers your Weight (blood volume) and your Gender (water content). Since alcohol dissolves in water, men generally have a lower BAC than women for the same number of drinks because male bodies typically contain more water (muscle tissue) and less fat.
Understanding the Legal Limit (0.08%)
In the United States, Canada, and the UK, the legal limit for driving is 0.08% BAC. However, impairment starts much earlier.
| BAC % | Physical Effects |
|---|---|
| 0.02% | Relaxation, slight mood lift. Safe to drive for most. |
| 0.05% | Minor impairment of judgment, lowered alertness. Driving becomes risky. |
| 0.08% | LEGALLY INTOXICATED. Muscle coordination reduces, reaction time slows significantly. |
| 0.15% | Loss of balance, slurred speech. Blackout risk begins. |
The "One Drink per Hour" Rule
Your liver can only process alcohol at a fixed rate. On average, the human body metabolizes 0.015% BAC per hour.
If your BAC is 0.15% (drunk), it will take roughly 10 hours to reach 0.00% (sober).
This is why people still get arrested for DUI the morning after a party. You might feel awake, but your blood is still over the limit.
Myths About Sobering Up
There are many myths about how to lower your BAC faster. None of them work because you cannot speed up your liver.
- Coffee: Makes you an "Awake Drunk," but does not lower BAC.
- Cold Showers: Will wake you up, but the alcohol remains in your blood.
- Bread/Food: Eating before drinking slows absorption. Eating after drinking does nothing to lower the alcohol already in your blood.
What counts as "One Drink"?
Not all drinks are equal. A "Standard Drink" contains roughly 14 grams of pure alcohol.
- Beer: 12 oz at 5% ABV. (Be careful with Craft IPAs, which can be 7-9%!).
- Wine: 5 oz at 12% ABV. (A typical restaurant pour is often 6-8 oz, which is 1.5 drinks).
- Spirits: 1.5 oz (a shot) at 40% ABV.