Water Intake Calculator
Estimate your daily hydration target from weight and activity.
How to use this tool
- Enter your weight (metric or imperial).
- Add daily exercise minutes and intensity.
- Optionally set hot-climate offset.
- See your daily target and per-sitting suggestions.
How it works
Baseline = weight x 35 ml/kg (24 oz per 100 lb equivalent); exercise adds per-minute amounts scaled by intensity; climate adds a top-up.
Tips
- Hydrate before, during and after exercise, not all at once.
- Food provides ~20% of fluid — slightly lower your target if unsure.
Limitations
Guidelines vary by age, health and climate — this is a general estimate, not medical advice.
Frequently asked questions
How much water should I drink per day?
A common baseline is about 35 ml per kg of body weight, plus extra for exercise — the calculator combines both.
Does activity increase needs?
Yes — roughly 350-500 ml per 30 minutes of exercise is added, adjusted for sweat rate.
What about the '8 glasses' rule?
It's a rough proxy; weight-based targets are more personal, which is what this tool uses.