How the water calculator works
It starts with about 35 ml of water per kg of body weight (roughly half an ounce per pound). Then it adds about 12 oz (350 ml) for every 30 minutes of exercise, and 17 oz (500 ml) extra for hot or humid weather.
What the US guidelines say
The US National Academies suggest a total daily water intake of about 3.7 liters (125 oz) for men and 2.7 liters (91 oz) for women. That total includes water from food, which usually covers about 20%.
Signs you are drinking enough
- Your urine is pale yellow.
- You rarely feel very thirsty.
- You don't get headaches or feel tired from mild dehydration.
Coffee, tea, milk and water-rich foods like fruit and soup all count toward your total.
How to use the water intake calculator
Enter your weight, how many minutes you exercise per day, and whether it's hot or humid where you live. The result shows your daily target in fluid ounces (or liters), plus cups and bottles.
Water intake example
A 180 lb person who exercises 30 minutes a day needs roughly 3.2 liters, or about 108 oz (13 to 14 cups), of fluids. On a hot day, that rises to about 125 oz.
How much water by body weight
| Body weight | Base daily water |
|---|---|
| 120 lb | about 64 oz (8 cups) |
| 150 lb | about 81 oz (10 cups) |
| 180 lb | about 97 oz (12 cups) |
| 210 lb | about 113 oz (14 cups) |
| 240 lb | about 129 oz (16 cups) |
Add about 12 oz for every 30 minutes of exercise.
Tips to drink more water
- Keep a refillable bottle with you and refill it at set times.
- Drink a glass with every meal.
- Add lemon, cucumber or berries for flavor.
- Eat water-rich foods like fruit, vegetables and soup.
Frequently asked questions
Is 8 glasses of water a day enough?
Eight 8-oz glasses (64 oz) is a reasonable minimum for many adults, but larger or active people usually need more.
Can you drink too much water?
Yes, drinking very large amounts in a short time can be dangerous. Spread your water through the day.
Does coffee count toward water intake?
Yes. Coffee and tea have a mild effect on urine, but they still add to your daily fluid.
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