Water Intake Calculator
Find your optimal daily hydration goal
kg
Daily Water Intake
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In Glasses (250ml)
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In ml
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What is the water intake calculator?
Daily water intake is the amount of water your body needs to maintain proper hydration, support metabolism, regulate body temperature, and flush waste products. Hydration needs vary significantly based on body weight, physical activity, and climate. Most people drink far less than they need.
Formula used
Base formula: Water (ml) = Body weight (kg) × 35
Adjusted formula:
Water = Weight × 35 × Activity multiplier × Climate multiplier
Activity multipliers:
Sedentary: ×1.0 Lightly active: ×1.2
Moderately active: ×1.4 Very active: ×1.6
Climate multipliers:
Temperate: ×1.0 Hot & humid: ×1.1 Cold: ×0.9
How to use this calculator
- Enter your body weight in kg
- Select your typical activity level
- Select your climate
- Click Calculate — see daily litres, ml, and number of glasses
Example
Example 1 — Office worker in Mumbai (hot climate):
Weight: 65 kg | Activity: Sedentary (×1.0) | Climate: Hot & humid (×1.1)
Water = 65 × 35 × 1.0 × 1.1 = 2,502 ml ≈ 10 glasses/day
Example 2 — Active person in Delhi:
Weight: 80 kg | Activity: Very active (×1.6) | Climate: Temperate (×1.0)
Water = 80 × 35 × 1.6 × 1.0 = 4,480 ml ≈ 18 glasses/day
Dehydration warning signs:
| Urine colour | Hydration status | Action |
|---|---|---|
| Pale yellow | Well hydrated ✓ | Maintain intake |
| Yellow | Slightly dehydrated | Drink more water |
| Dark yellow/amber | Dehydrated ✗ | Drink immediately |
Frequently asked questions
It is a rough approximation. The 8×8 rule (8 glasses of 8 oz = ~1.9 litres) is too low for many people, especially in India's hot climate and for active individuals. A personalised calculation is more accurate.
Yes, despite the common myth, caffeinated drinks contribute to hydration. Coffee and tea are primarily water. Alcohol is dehydrating and should not count.
Water intoxication (hyponatremia) is rare but possible if you drink large amounts very rapidly. For most people, staying close to your calculated target is perfectly safe.