Hong Life CalculatorsUnderstanding the alcohol calories and elimination calculator — concept and principle
Alcoholic drinks carry energy that is easy to overlook, and the alcohol itself takes hours to leave the body. This calculator converts your drinks into grams of pure alcohol, then estimates the calories, the time your liver needs to clear it and a rough peak blood alcohol concentration (BAC) using the Widmark formula.
How it is calculated
- Alcohol (g) = volume (mL) × ABV ÷ 100 × 0.789 × number of drinks
- Calories = alcohol (g) × 7
- Hours to eliminate = alcohol (g) ÷ (weight × 0.1)
- Peak BAC (%) = alcohol (g) ÷ (weight (kg) × 1,000 × r) × 100, with r = 0.68 for men and 0.55 for women
ABV is alcohol by volume in percent; 0.789 g/mL is the density of ethanol.
The principle
ABV tells you what share of the drink's volume is ethanol, and multiplying by ethanol's density turns that volume into grams. Each gram of alcohol supplies about 7 kcal, nearly as much as fat. The liver breaks alcohol down at a roughly constant rate, about 0.1 g per kilogram of body weight per hour, which is why time, not coffee or a shower, is the only way to sober up. Erik Widmark's formula spreads the alcohol through the body's water: r is the share of body mass in which alcohol distributes, lower in women on average because of a higher proportion of body fat. The peak figure assumes all alcohol is absorbed at once and ignores elimination while drinking, so real peaks are usually somewhat lower.
Worked example
- Default inputs: 75 kg man, three 500 mL drinks at 5% ABV.
- Alcohol = 500 × 0.05 × 0.789 × 3 = 59.175 g, shown as 59 g.
- Calories = 59.175 × 7 ≈ 414.2, shown as 414 kcal.
- Hours to eliminate = 59.175 ÷ (75 × 0.1) = 7.89 h.
- Peak BAC = 59.175 ÷ (75,000 × 0.68) × 100 ≈ 0.116%.
The calculator shows 414 kcal, 59 g of alcohol, 7.89 hours and a peak BAC of 0.116%.
| Drink volume (mL) | Calories from alcohol |
|---|---|
| 125 | 104 |
| 250 | 207 |
| 375 | 311 |
| 500 | 414 |
| 625 | 518 |
| 750 | 621 |
| 1,000 | 828 |
How to read the result
A BAC of 0.116% is well above the legal driving limits in most countries, which are typically 0.05% or 0.08%; in Korea, licence suspension starts at 0.03%. Elimination of almost eight hours means you could still be over a limit the next morning after a late night.
Common mistakes
- Treating the BAC estimate as proof that you are safe to drive.
- Assuming coffee, water or exercise speeds up elimination.
Frequently asked questions
Why does a woman of the same weight reach a higher BAC?
On average women have less body water per kilogram, so the same alcohol is more concentrated.
Does eating before drinking help?
Food slows absorption and lowers the peak, but it does not reduce the total alcohol to be cleared.
Are alcohol calories stored as fat?
The body burns alcohol first, which pushes aside fat burning, so extra calories from other foods are more likely to be stored.
Sources: Widmark EMP. Die theoretischen Grundlagen und die praktische Verwendbarkeit der gerichtlich-medizinischen Alkoholbestimmung. Berlin: Urban & Schwarzenberg, 1932. · Republic of Korea Road Traffic Act, Article 44 (prohibition of driving under the influence of alcohol).