Hangover Hydration Calculator

Work out hangover hydration instantly with clear inputs, formula shown and shareable results.

About Hangover Hydration Calculator

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.

Formulas

Fluid deficit

deficit ml = standard drinks x extra urine output per drink

Total intake

total = body weight kg x 35 ml + deficit

Worked example

With the default values below, Hangover Hydration Calculator returns Extra fluid to replace of 500. Change any input above and every figure here is recalculated in your browser.

Inputs used

Standard drinks consumedminimum 0.5: 5
Body weightminimum 20 kg: 70 kg
Extra urine output per drinkminimum 10 ml: 100 ml

Results

Extra fluid to replace: 500 ml
Total fluid for the day: 2,950 ml
Sodium to replace with it: 400 mg
250 ml glasses: 11.8

Step by step

1Values used
2Fluid deficit
3Total intake
4Extra fluid to replace= 500 ml
5Total fluid for the day= 2,950 ml
6Sodium to replace with it= 400 mg
7250 ml glasses= 11.8

Assumptions and limits

The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 1 decimal place, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is the Hangover Hydration figure worked out?

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.

Why does this matter?

Plain water alone dilutes remaining electrolytes, which is why rehydration works better with some sodium rather than volume by itself.

What do I need to enter?

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.