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Water Intake Calculator

Estimate how much water to drink each day based on your weight, exercise habits, and environment. Hydration supports energy, digestion, and performance.

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Adjust the sliders and tap Calculate to see your hydration target.
This tool provides general informational estimates only and is not medical advice, diagnosis, or treatment. Results use population-average formulas and may not fit your individual situation. Always consult a qualified healthcare professional before making health, diet, or medical decisions.

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How much water should you drink?

There is no single perfect number for everyone. Needs depend on body size, sweat loss, climate, pregnancy, and health conditions. This tool gives a practical starting estimate.

How this calculator works

It starts with about 35 ml per kg of body weight as a baseline, then adds extra fluid for exercise and hot climates. Thirst, urine color, and how you feel are useful day-to-day guides.

Track water alongside meals and workouts in the SmartEat app for a fuller picture of your daily habits.

Frequently asked questions

How much water should I drink per day?

A common starting point is roughly 30–35 ml per kg of body weight, plus extra for exercise and heat. Many adults land around 2–3 liters from beverages, with additional fluid from food.

Does coffee count toward water intake?

Yes, in moderation. Caffeinated drinks contribute to fluid intake, though very high caffeine may increase losses slightly for some people.

Do I need to drink exactly this amount every day?

No. Use this as a guide. Drink more when you sweat heavily, feel thirsty, or are in hot weather; less may be fine on rest days if you feel well hydrated.

Sources & methodology

Formulas and reference ranges used by this calculator come from peer-reviewed and official public-health sources:

  1. U.S. National Academies — general hydration guidance: about 2.7 L/day for women and 3.7 L/day for men from all beverages and food (total fluid intake).
  2. European Food Safety Authority — adequate intake of water from all sources: 2.0 L/day for women and 2.5 L/day for men.
  3. American College of Sports Medicine — additional fluid before, during, and after exercise in hot or strenuous conditions.
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