Health

Daily Water Intake Calculator

Personalized hydration goal based on body weight, activity, climate, and life stage. Free, no sign-up.

Metric (kg, mL) Imperial (lb, oz)

Weight (kg)

Daily exercise

Climate

Temperate Hot / humid

Life stage

None Pregnant Breastfeeding

Daily target

— mL

Enter your weight to see your target

Glasses (250 mL) —

Bottles (500 mL) —

Suggested pace —

How much water do you actually need?

There's no single "8 glasses a day" number that fits everyone. Your real water need depends on body size, activity, climate, diet, and life stage. The European Food Safety Authority and the U.S. Institute of Medicine give general adequate-intake numbers (around 2.5 L for men and 2 L for women), but those are population averages — they include water from food, not just drinks. A more individualized approach is to start with body weight: roughly 30-35 mL per kilogram (about 0.5 oz per pound) per day from beverages, then add about 350 mL for every 30 minutes of training, an extra 500 mL or so on hot/humid days, and 300 mL during pregnancy or 700 mL while breastfeeding. Coffee and tea count toward total fluids — modest caffeine doesn't dehydrate. Use thirst, urine color (pale-yellow is the target), and energy as feedback. Drinking far more than you need doesn't deliver extra benefit; in rare cases (mostly extreme endurance events) it can cause hyponatremia. This calculator is informational; people with kidney, heart, or hormone conditions should follow medical guidance instead.

How to use this calculator

1. Enter your weight in kg or lb. 2. Pick the activity level that matches an average day for you (use your weekly average if it varies a lot). 3. Choose your climate — "hot" applies whenever you're sweating from heat or humidity rather than only from exercise. 4. If you're pregnant or breastfeeding, select that. The result shows total daily fluid in mL or oz, plus how that breaks down into 250 mL glasses or 500 mL bottles, and a suggested pace from morning to evening.

How the target is calculated

Target = 32 × weight(kg) + (active min ÷ 30) × 350 + climate bonus + life-stage bonus — where the climate bonus is 500 mL for hot/humid and 0 otherwise, and the life-stage bonus is 300 mL (pregnant) or 700 mL (breastfeeding). The 32 mL/kg coefficient is the midpoint of the commonly cited 30-35 mL/kg range. For imperial output we convert mL to fluid ounces (1 oz ≈ 29.5735 mL).

Quick-reference targets

Approximate daily targets by body weight and activity, in temperate climate, with no pregnancy/breastfeeding bonus.

Weight	Sedentary	60 min training	90 min training
50 kg / 110 lb	1.6 L / 54 oz	2.3 L / 78 oz	2.7 L / 91 oz
60 kg / 132 lb	1.9 L / 65 oz	2.6 L / 89 oz	3.0 L / 102 oz
70 kg / 154 lb	2.3 L / 77 oz	3.0 L / 100 oz	3.4 L / 113 oz
80 kg / 176 lb	2.6 L / 88 oz	3.3 L / 112 oz	3.7 L / 124 oz
90 kg / 198 lb	2.9 L / 99 oz	3.6 L / 122 oz	4.0 L / 135 oz
100 kg / 220 lb	3.2 L / 110 oz	3.9 L / 133 oz	4.3 L / 146 oz

Frequently asked questions

Does coffee or tea count?

Yes. Modest amounts of caffeine don't cause net dehydration in habitual drinkers. Coffee, tea, milk, broth, and most non-alcoholic drinks contribute to your total fluid intake. Alcohol counts negatively because it suppresses ADH and increases urine output.

Should I drink even when not thirsty?

For most healthy adults, thirst is a reliable signal. Older adults, pregnant women, and people doing prolonged endurance activity benefit from sipping on a schedule, because thirst lags. Use urine color as a daily check — pale yellow is well-hydrated.

Can I drink too much water?

Yes, though it's rare in everyday life. Drinking many liters quickly during very long endurance events can cause hyponatremia (low blood sodium), which is dangerous. The rule of thumb: don't override thirst at extreme volumes.

Why does the target jump on hot days?

Sweating loses both water and electrolytes. In hot or humid climates, daily sweat losses can exceed 1-2 L even without formal exercise. The +500 mL bump is a baseline; if you're working outdoors in heat, you may need much more, with electrolytes.

Does food count toward hydration?

Food contributes about 20% of total water intake in a typical diet — fruits, vegetables, soups, yogurt and cooked grains all carry water. This calculator targets fluids from drinks only; food water is on top of that.

Is this medical advice?

No. It's a general estimate for healthy adults. People with kidney disease, heart failure, SIADH, or on certain medications need individualized fluid targets — please follow your doctor's guidance.

Daily Water Intake Calculator