What formula is used to calculate water intake?

The baseline is 35 ml per kilogram of body weight. Activity adjustments add 500 ml for moderate activity and 1000 ml for intense activity. A hot climate adds another 300 ml. Pregnancy adds 300 ml and breastfeeding adds 500 ml.

Is the 8 glasses a day rule accurate?

The '8×8' rule (eight 8-ounce glasses) is a rough approximation. Individual needs vary significantly based on body weight, activity level, climate, diet, and health status. This calculator provides a more personalized estimate.

Does coffee or tea count toward my intake?

Caffeinated beverages have a mild diuretic effect but still contribute to hydration. A general guideline is to count them at about 80% of their volume. Plain water, herbal teas, and water-rich foods like fruits also count.

How does the reminder schedule work?

The tool divides your total daily intake evenly across your waking hours and generates a list of recommended drinking times. For example, if you're awake 16 hours and need 2.8 L, it suggests about 175 ml every hour.

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Water Intake Calculator

Calculate your personalized daily water intake recommendation with an hourly reminder schedule.

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About this tool

Enter your weight, activity level, and climate to get a science-based daily water intake recommendation using the 35 ml/kg baseline formula with adjustments for moderate activity (+500 ml), intense activity (+1000 ml), and hot climates (+300 ml). The tool also generates a custom hourly reminder schedule based on your wake and sleep times, and includes fun hydration facts.

How to use

1 Step 1: Enter your body weight in kilograms or pounds and select your typical daily activity level.
2 Step 2: Choose your climate (hot, temperate, or cold) and toggle the pregnancy or breastfeeding adjustment if applicable.
3 Step 3: View your recommended daily intake in liters and the equivalent number of 250 ml glasses.
4 Step 4: Set your wake-up and bedtime to generate an hourly drinking schedule that spreads your intake evenly throughout the day.

About this tool

How to use

Frequently Asked Questions