Water Intake Calculator
Estimate how much water you should drink each day. The calculation is based on your body weight and adjusts for the time you spend exercising.
Enter your values
Result
About 20% of daily fluid typically comes from food. Increase intake in hot weather, at altitude, or during illness.
How to use
Step-by-step guide for this tool
View steps ⟶Related tools
More calculators like this one
Browse ⟶Save result
Copy, share or print your result
Save ⟶How to use the Water Intake Calculator
- 1Enter weight (kg) in the form on the left.
- 2Fill in the remaining fields — the result updates automatically as you type.
- 3Review the highlighted result and the supporting breakdown on the right.
- 4Use Copy, Share or Print to save or send your result.
How much water do you really need?
A common evidence-aligned guideline is roughly 30–35 ml of fluid per kilogram of body weight daily, plus about 350 ml for every 30 minutes of exercise. For a 70 kg adult that's around 2.3 liters before training.
The popular 'eight glasses a day' rule is a reasonable average but ignores body size, climate and activity. Pale-yellow urine is the simplest practical indicator of good hydration.
Frequently Asked Questions
▸Do coffee and tea count toward water intake?
Yes. Despite mild diuretic effects, caffeinated drinks still contribute net fluid. Alcohol does not count.
▸Can you drink too much water?
Yes — excessive intake in short periods can cause hyponatremia (dangerously low sodium). Spread intake through the day and let thirst guide you during normal activity.