How much water should I drink per day?

A common baseline is about 30–35 ml per kilogram of body weight, plus more if you exercise or are in a hot climate — this calculator uses that approach.

Does the 8 glasses a day rule still apply?

The "8 glasses" rule (about 2 liters) is a simple general guideline, but individual needs vary considerably with body size, activity, and climate — a weight-based estimate tends to be more personalized.

Does water from food and other drinks count?

Yes — roughly 20% of daily water intake typically comes from food, so this estimate is a helpful target rather than a requirement met by plain water alone.

Health & Fitness

Water Intake Calculator

Enter your weight and daily exercise minutes to see a recommended daily water intake in liters, cups, and fluid ounces.

Your calculation is performed in your browser.

Enter your weight above to find your recommended daily water intake.

This result is an estimate for informational and educational purposes. It isn’t a diagnosis and isn’t a substitute for advice from a doctor, registered dietitian, or other qualified professional. See our methodology and sources for the formula used and its limitations.

How it works

The calculator uses a commonly cited baseline of about 33 ml of water per kilogram of body weight per day, then adds extra water for time spent exercising, since sweat losses increase fluid needs.

Formula & methodology

Water (ml) = (weight (kg) × 33) + (exercise minutes ÷ 30 × 350).

Worked example

A 70 kg person who exercises for 45 minutes needs roughly 2.8 liters (about 12 cups) of water per day.

Important notes

—This is a general estimate — climate, individual sweat rate, and overall diet (including water from food) all affect real hydration needs.
—Thirst, urine color, and how you feel are useful everyday indicators alongside any calculated target.