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Water Intake Calculator

Calculate how much water you should drink daily based on your weight, activity level, and climate. Stay properly hydrated with a personalized recommendation.

Daily Water Recommendation

2.8
liters per day
2,800 ml
Milliliters
95 oz
Fluid Ounces
11
Cups (250ml)
Base (weight-based)2,450 ml
Activity addition+350 ml
Climate addition+0 ml

How to Use This Tool

  1. Enter your body weight in kilograms.
  2. Select your activity level, from Sedentary to Very Active, based on how much you exercise.
  3. Select your climate — Temperate, Warm/Humid, or Hot/Tropical — based on where you live or are currently active.
  4. View your recommended daily water intake in liters, milliliters, fluid ounces, and standard 250 ml cups.
  5. Check the breakdown showing how much of your total comes from your base weight-based need, activity, and climate.

Formula & How It Works

Daily Water Intake

Daily Water (ml) = (Weight (kg) × 35) + Activity Addition + Climate Addition

A base of 35 ml per kilogram of body weight is used as the starting point, then extra water is added for exercise-related sweat loss and hot/humid climates.

Activity Addition

Sedentary +0 ml, Light +350 ml, Moderate +700 ml, Active +1,050 ml, Very Active +1,400 ml

Each activity tier adds a fixed amount of water to replace fluid typically lost through exercise-induced sweating.

Climate Addition

Temperate +0 ml, Warm/Humid +500 ml, Hot/Tropical +750 ml

Hotter and more humid environments increase perspiration, so additional water is added on top of the activity adjustment.

Practical Examples & Common Use Cases

Example — 70 kg, Light activity, Temperate climate

Base = 70 × 35 = 2,450 ml. Add 350 ml for Light activity and 0 ml for Temperate climate. Total = 2,450 + 350 + 0 = 2,800 ml ≈ 2.8 liters (about 95 fl oz, or roughly 11 cups).

Example — 85 kg, Moderate activity, Warm/Humid climate

Base = 85 × 35 = 2,975 ml. Add 700 ml for Moderate activity and 500 ml for Warm/Humid climate. Total = 2,975 + 700 + 500 = 4,175 ml ≈ 4.2 liters (about 141 fl oz, or roughly 17 cups).

Example — 60 kg, Sedentary, Hot/Tropical climate

Base = 60 × 35 = 2,100 ml. Add 0 ml for Sedentary activity and 750 ml for Hot/Tropical climate. Total = 2,100 + 0 + 750 = 2,850 ml ≈ 2.9 liters (about 96 fl oz, or roughly 11 cups) — showing how climate alone can significantly raise water needs even without exercise.

Frequently Asked Questions

The 8×8 rule (eight 8-oz glasses = ~2 liters) is a simple guideline but not based on strong science. Actual needs vary significantly by body size, activity, and climate. This calculator provides a more personalized estimate.

Yes, though rare. Hyponatremia (water intoxication) can occur from drinking extreme amounts quickly. Spread your intake throughout the day and listen to your body.

Yes, caffeinated beverages do contribute to hydration despite mild diuretic effects. The net effect is still hydrating. However, water is the best primary source.

Yes, illness (especially fever, vomiting, diarrhea) increases fluid needs. Drink extra water and consider electrolyte solutions during illness.

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