Hangover Hydration Calculator

How it is calculated

The tool uses a simple rule of thumb: drink back as much water as the volume of the drinks you had.

rehydration (mL) = drinks × mL per drink

rehydration (L) = rehydration (mL) / 1000

drinks is the number of drinks, and fractions such as 2.5 are accepted. mL per drink is the serving size in millilitres, for example about 330 for a small bottle of beer or 150 for a glass of wine. Both results are shown with two decimals. The tool does not use body weight, the alcohol strength, or the time since drinking, and it does not add anything for electrolytes. Both inputs must be above zero. It is a rough guide for ordinary situations, not medical advice, and it is not a treatment for alcohol poisoning.

Common mistakes

• Entering the serving size in ounces or in centilitres (25 cl). The field takes millilitres, so a 25 cl glass must be entered as 250.
• Entering the amount of pure alcohol (14 g) instead of the whole serving volume. The tool multiplies drinks by the volume of liquid.
• Forgetting that a cocktail, a pint or a double counts as more than one standard glass. Count the real volume poured, not the number of orders.
• Drinking the whole amount at once. A litre of plain water in a short time can upset the stomach; sip it over hours.
• Treating the result as a cure. Water replaces fluid but does not remove alcohol faster, and severe symptoms such as repeated vomiting or confusion need medical help.