Work out hangover hydration instantly with clear inputs, formula shown and shareable results.
Alcohol suppresses vasopressin so each standard drink adds roughly 100 ml of urine output; the replacement need is that deficit on top of a normal 35 ml per kg daily intake, with sodium at about 800 mg per litre replaced. Plain water alone dilutes remaining electrolytes, which is why rehydration works better with some sodium rather than volume by itself.
Fluid deficit
deficit ml = standard drinks x extra urine output per drink
Total intake
total = body weight kg x 35 ml + deficit
deficit ml = standard drinks x extra urine output per drink. Alcohol suppresses vasopressin so each standard drink adds roughly 100 ml of urine output; the replacement need is that deficit on top of a normal 35 ml per kg daily intake, with sodium at about 800 mg per litre replaced.
Plain water alone dilutes remaining electrolytes, which is why rehydration works better with some sodium rather than volume by itself.
Enter standard drinks consumed, body weight, extra urine output per drink. The defaults shown are a realistic worked example — swap in your own figures to get a result you can use.