Water Intake Calculator
Calculate your recommended daily water intake based on weight, activity and climate.
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Based on ~33ml per kg. Adjust for activity and climate. This is a guideline.
What is a Water Intake Calculator?
A water intake calculator estimates how much water you should drink each day based on your body weight, activity level, and environment. Proper hydration supports energy, digestion, skin health, and overall wellbeing.
How Water Intake is Estimated
Base Formula
Daily water (ml) ≈ Weight (kg) × 33
This gives a baseline of about 33ml per kilogram of body weight per day.
Adjustments
- Activity: More exercise = more sweat = more water needed. We apply multipliers from 1.0 (sedentary) to 1.4 (very active).
- Climate: Hot or humid conditions increase fluid loss. We apply multipliers for hot (1.2) and very hot (1.3) climates.
Example
- 70 kg person, moderate activity, normal climate
- Base: 70 × 33 = 2,310 ml
- With moderate multiplier (1.2): 2,772 ml ≈ 2.8 litres per day
How Our Calculator Works
- Enter weight: In kg or lbs
- Select activity level: Sedentary to very active
- Select climate: Normal, hot, or very hot
- Get results: Daily intake in litres, cups, and glasses
General Guidelines
- 8 glasses a day is a common rule of thumb (~2 litres)
- Thirst is a good indicator—drink when you’re thirsty
- Urine colour: Pale yellow = well hydrated; dark = drink more
- Food contributes: About 20% of fluid comes from food
Frequently Asked Questions
How much water should I drink per day?
A common guideline is 2–2.5 litres (8–10 glasses) for adults. Our calculator personalises this based on your weight, activity, and climate.
Does coffee count toward water intake?
Moderate coffee can contribute to fluid intake, but caffeine has a mild diuretic effect. Water is still the best choice for hydration.
Can you drink too much water?
Yes. Hyponatremia (low sodium) can occur with excessive water intake. For most people, drinking to thirst is safe. Athletes doing long events should balance water with electrolytes.
Do I need more water when exercising?
Yes. Sweat losses need to be replaced. Drink before, during, and after exercise. For intense or long sessions, consider electrolyte drinks.