# Does wine dehydrate you? A glass, measured

A 150 ml glass of red wine is 16 g of alcohol and 128 calories, and counts as only 75 ml toward your water goal. The numbers behind the halving.

## Numbers the app uses

| Field | Value |
| --- | --- |
| Default serving | 150 ml |
| Hydration factor | 0.50 |
| Counts toward the daily goal | 75 ml per serving |
| Calories | 85 kcal per 100 ml (128 kcal per serving) |
| Alcohol | 13.5% ABV (16 g per serving) |

## The alcohol is three times as concentrated as beer

Compare the two by the millilitre rather than by the glass. Red wine at 13.5%
carries about 0.107 g of alcohol in every millilitre of liquid. A 5% beer
carries 0.039 g. Wine delivers nearly three times the alcohol dose per unit of
fluid. The same amount of ethanol arrives with a third of the water to offset
the urine it provokes. A 150 ml glass is 16 g of pure alcohol in a volume
smaller than a coffee cup.

The hydration factor of 0.50 is the app's response to that. It is a deliberate,
conservative discount, not a laboratory measurement, and the difference
matters. The Beverage Hydration Index trial never tested wine. It tested a weak
lager, which came out level with water. That result does not transfer to a
drink with triple the alcohol density. So the catalog halves wine and sets neat
spirits to zero. Mixed drinks such as a mojito or a margarita sit alongside the
wines at 0.50.

## A bottle is five glasses, and 80 g of alcohol

The serving size in the app is 150 ml because that is the pour most guidance
treats as standard. A 750 ml bottle holds five of them. Restaurant pours are
routinely 175 or 250 ml. The glass in front of you may well be 19 or 27 g of
alcohol rather than 16. Move the serving control above to whatever was
actually poured, and the alcohol, calorie and hydration figures follow.

## Most of those calories are the alcohol itself

128 calories in a 150 ml glass makes red wine denser in calories per millilitre
than cola. That surprises people who think of wine as the lighter choice.
Alcohol supplies about 7 calories per gram, so those 16 g account for roughly
112 of the 128. The residual sugar in a dry red is almost nothing; you are
drinking the ethanol, not the grapes. Dry white and rosé sit slightly lower
again, and the app lists them separately for exactly that reason.

## Source

Hydration factors follow the Beverage Hydration Index. Maughan RJ, Watson P, Cordery PA, et al. “A randomized trial to assess the potential of different beverages to affect hydration status: development of a beverage hydration index.” American Journal of Clinical Nutrition, 2016;103(3):717-723. https://pubmed.ncbi.nlm.nih.gov/26702122/

Page: https://waterchamp.app/drinks/wine/