- Default serving330 mlSoft drink
- Counts toward goal330 mlhydration factor 1.00
- Caffeine33 mgper 330 ml serving
- Calories139 kcal42 kcal per 100 ml
Move the slider to see what a bigger or smaller cola does to the numbers. The app uses the same figures.
See when today's caffeine clears with the caffeine cutoff calculator.
The dose is too small to dry you out
A 330 ml can holds 33 mg of caffeine, roughly a tenth of a milligram per millilitre. Filter coffee runs at about 0.27 mg per millilitre, so cola is around a third as strong, glass for glass. Caffeine starts producing extra urine only at far higher doses, and mostly in people who are not used to it. To get there on cola you would need close to three litres in one sitting.
That is exactly what the controlled trial found. It gave volunteers a litre of each of thirteen drinks and weighed every urine sample for the next four hours. Cola and diet cola came out level with still water. The drinks that beat water were the ones carrying salt and food: oral rehydration solution and milk. So the app gives cola a hydration factor of 1.00. Drink 330 ml, get 330 ml toward the goal.
The beverages that retained more fluid than water were not the ones without caffeine. They were the ones with sodium.
The part worth watching is the sugar
139 calories per can, essentially all of it sugar, is the real cost of the habit. Three cans a day is over 400 calories that never register as a meal. This is the one place where the diet version genuinely wins. But note one detail from the app's catalog: diet soda carries more caffeine per serving than cola does, at 46 mg per 355 ml. That mirrors what is actually in the cans. Switching to the sugar-free version to sleep better is a plan that quietly backfires.
Log the size you actually poured
Cola's caffeine scales with how much you pour. A 500 ml bottle is 50 mg and a small 200 ml glass is 20 mg. The app files that caffeine into the same metabolism curve as your coffee, which is the point. An evening cola with dinner is a small dose, but it lands on top of everything from the afternoon. The curve shows you the total rather than the individual drinks.
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. Read the paper on PubMed. In WaterChamp a cola counts the same as plain water.
