This water intake calculator estimates how much you should drink each day. It starts from the US National Academies’ recommended total water intake for men, women, pregnancy and breastfeeding, then adds extra for exercise and hot weather. Results are shown in liters, fluid ounces and cups.
Recommended daily water intake
| Group | Total water a day (all sources) | From drinks (about 80%) |
|---|---|---|
| Men | 3.7 L (125 fl oz) | About 3.0 L (13 cups) |
| Women | 2.7 L (91 fl oz) | About 2.2 L (9 cups) |
| Pregnancy | 3.0 L | About 2.4 L (10 cups) |
| Breastfeeding | 3.8 L | About 3.0 L (13 cups) |
About 20% of the water you need comes from food, especially fruit, vegetables and soups.
Extra water for exercise and heat
The calculator adds about 0.5 L (17 fl oz) per hour of exercise and 0.5 L on hot or humid days. Long or intense sessions in the heat may need more, along with electrolytes.
Signs you are drinking enough
- You rarely feel thirsty.
- Your urine is pale yellow.
Drinking far more than you need in a short time can be dangerous, so spread drinks through the day.
Frequently asked questions
Is 8 glasses of water a day right?
It is a reasonable rough guide for women, but needs vary. Men usually need more, and tea, coffee and food all count toward your total.
Does coffee count toward water intake?
Yes. Moderate amounts of coffee and tea still provide more water than they cause you to lose.
Can you drink too much water?
Yes. Drinking very large amounts quickly can lower blood sodium (hyponatremia), which can be serious. Endurance athletes are most at risk.
Do I need more water when I am sick?
Fever, vomiting and diarrhea all increase fluid loss. Use oral rehydration solutions if needed and see a doctor if you cannot keep fluids down.
Related calculators
Sources
Last reviewed: October 2026. For information only; not medical advice. Talk to a doctor about any health concerns.