Water Intake Calculator
Estimate how much water to drink each day from your weight, exercise and climate.
About the Water Intake Calculator
The US National Academies set an Adequate Intake of total water (from drinks and food) of about 3.7 L a day for men and 2.7 L for women; roughly 80% usually comes from drinks. This calculator scales that by body weight (about 33 mL per kg), then adds about 0.6 L per hour of exercise and 0.5 L for hot weather.
The formula
Water (L) ≈ 0.033 × weight (kg) + 0.6 × exercise hours (+ 0.5 if hot)
Worked example
Example: Drink about = 3 L (102 fl oz)
- Inputs: Units: lb / ft; Sex: Male; Weight: 180 lb; Exercise per day: 33 minutes; Climate: Mild.
- Formula: Water (L) ≈ 0.033 × weight (kg) + 0.6 × exercise hours (+ 0.5 if hot)
- Result: Drink about = 3 L (102 fl oz)
- Base (33 mL per kg): 2.69 L
- For exercise and heat: 0.33 L
- National Academies total water (all sources): 3.7 L
Things to keep in mind
- This is an estimate for general information, not medical advice. Talk to a doctor or other qualified professional about your health.
- People with heart or kidney conditions may need to limit fluids; follow medical advice.
Questions people ask
Do tea and coffee count?
Yes. Caffeinated drinks still hydrate overall.
How do I know if I'm drinking enough?
Pale yellow urine and rarely feeling thirsty are good signs.