Water Intake Calculator
Get a rough daily water target based on your weight and how much you exercise. This is general guidance, not medical advice — needs vary with climate, health, and diet.
Daily water
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Check it outA starting point, not a rule
A common rule of thumb is about half your body weight in ounces of water per day, plus extra for exercise — roughly 12 ounces per 30 minutes of activity. Hot weather, illness, pregnancy, and diet all change real needs, and food and other drinks count toward hydration too. Thirst and pale-yellow urine are decent everyday guides. This isn't medical advice.
How it’s calculated
Ounces ≈ half your body weight in pounds, plus about 12 oz per 30 minutes of exercise.
Results update as you type and are estimates, not professional advice — verify important decisions with a qualified professional.
Worked example
A 160-lb person with 30 minutes of exercise targets about 92 oz (~11.5 cups) of water a day.
Common mistakes
- Treating the rule of thumb as a strict requirement.
- Ignoring climate, health, and food, which all matter.
Where it is used
- Setting a rough daily hydration target.
- Adjusting intake for a workout day.
Frequently asked questions
Is the 'half your weight in ounces' rule real?
It's a popular rule of thumb, not a strict medical standard. Individual needs vary widely.
Does coffee or food count?
Yes — most beverages and water-rich foods contribute to hydration.
Can I drink too much water?
Rarely, but overhydration is possible. If you have kidney, heart, or other conditions, follow your doctor's guidance.