Free 0.5 BAC Limit Drink Estimator
Use this tool to estimate how many standard drinks may place you near a 0.5‰ BAC limit (equivalent to 0.05% BAC).
What does a 0.5 alcohol limit mean?
In many countries, the legal driving threshold is expressed as 0.5‰ BAC (per mille). This equals 0.05% BAC. The limit is not a “safe” level of impairment—only a legal cutoff in some places. Reaction time, judgment, and coordination can decline well before the legal maximum.
How many drinks is 0.5 BAC?
There is no single answer. The number of drinks that may bring someone close to 0.5‰ depends on multiple factors:
- Body weight and body composition
- Biological sex and water distribution ratio
- How quickly drinks are consumed
- Food intake before and during drinking
- Drink size and alcohol percentage
- Individual metabolism (which varies widely)
That is why calculators provide estimates rather than guarantees.
How this calculator works
This page uses a simplified Widmark-style formula:
- BAC (‰) ≈ A / (r × W) − β × t
- A = grams of pure alcohol consumed
- r = body distribution factor (about 0.68 male, 0.55 female, 0.62 average)
- W = body weight in kg
- β = alcohol elimination rate (about 0.15‰ per hour)
- t = hours since drinking started
To estimate “how many drinks to reach 0.5,” the formula is rearranged to solve for total alcohol grams and then divided by grams per standard drink.
Important assumptions
The model assumes absorption and elimination patterns that may not match your body. In real life, BAC can be higher or lower than predicted. Breath or blood testing by authorities is what counts legally—not any online calculator.
Quick reference examples (illustrative only)
| Profile | Hours Since First Drink | Standard Drink (10g) | Estimated Drinks Near 0.5‰ |
|---|---|---|---|
| 60 kg, r=0.55 | 1 hour | 10 g | ~2.1 drinks |
| 70 kg, r=0.62 | 1 hour | 10 g | ~2.8 drinks |
| 80 kg, r=0.68 | 1 hour | 10 g | ~3.5 drinks |
These examples are broad estimates, not a personal recommendation.
Tips to reduce risk
- Choose a designated driver before drinking starts.
- Use rideshare, taxi, or public transit if alcohol is involved.
- Do not rely on coffee, cold showers, or “feeling fine.” They do not lower BAC.
- Track drink strength: craft beer, cocktails, and large pours often exceed one standard drink.
Frequently asked questions
Is 0.5 the same as 0.05?
They represent the same concentration in different units: 0.5‰ equals 0.05%.
Can I calculate exactly when I’m legal to drive?
No. You can only estimate. Legal status depends on actual measured BAC and local law. If in doubt, do not drive.
Does eating food make BAC zero?
No. Food can slow absorption, but it does not cancel alcohol already consumed.
Bottom line
A “0.5 alcohol limit how many drinks” calculator can help you understand the math, but it cannot guarantee safety or legality. Use it as an educational planning tool, not as permission to drive after drinking.