HowMuchWaterDoINeed?
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Discover your personalized daily water intake based on your unique profile.
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Your Daily Glasses Needed
Daily Hydration Tips
Simple habits for optimal hydration
How Much Water to Drink a Day — and How We Calculate It
There is no single right number for everyone. This daily water intake calculator starts with your body weight — about 35 ml per kilogram for adults, based on Institute of Medicine reference values — then adjusts for your age group, activity level, and climate. Pregnancy and breastfeeding raise the target further: nursing adds roughly 700 ml a day while you are producing milk. The result is your total for the day from all drinks and food, not a count of plain-water glasses — soup, milk, tea, and fruit all contribute. Use thirst and urine colour as the everyday check: pale straw means you are on target.
Benefits of Proper Hydration
Here's how staying hydrated helps your body function at its best
Improves focus, memory, and mental clarity
Maintains healthy blood pressure and circulation
Enhances endurance and muscle function
How Much Water Should You Drink a Day?
Most adults aged 19–64 years need about 35 mL of water per kilogram of body weight per day — 2.45 L for a 70 kg adult, or about 2.6 L with moderate activity. Baseline needs per kilogram are highest for infants and taper with age; the adjustments below apply on top of them.
Baseline by age group
| Age group | Baseline (mL per kg of body weight per day) |
|---|---|
| 0–6 months | 150 |
| 7–12 months | 100 |
| 1–3 years | 90 |
| 4–8 years | 70 |
| 9–13 years | 50 |
| 14–18 years | 40 |
| 19–64 years | 35 |
| 65+ years | 30 |
Infants (0–12 months): these values describe total fluid intake, which comes primarily from breast milk or formula — not additional water.
- Water intake primarily through breast milk or formula.
- Additional water only under medical supervision.
- Risk of water intoxication with excessive water intake.
- Introduction of small amounts of water with solid foods.
- Continued reliance on breast milk or formula for hydration.
Main adjustments
- Female sex: × 0.95 (about 5% lower baseline, reflecting body composition).
- Activity: + 3% light, + 7% moderate, + 12% intense, + 20% extreme (adults 19–64 years).
- Pregnancy: + 10% of the adjusted baseline, phased 70% / 100% / 130% across the first, second, and third trimesters.
- Breastfeeding: + 20% of the adjusted baseline, scaled by nursing stage.
- Climate: hot, humid, or high-altitude conditions increase fluid needs — the calculator applies a climate adjustment when detection is enabled.
Sources: Institute of Medicine (IOM), Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate (2005); WHO, Water Requirements, Impinging Factors, and Recommended Intakes (2003); EFSA, Scientific Opinion on Dietary Reference Values for water (2010); American College of Sports Medicine (ACSM), Exercise and Fluid Replacement Position Stand (2007).
Signs of Dehydration
Know the warning signs and stay ahead of dehydration
Dark Urine Color
Your urine should be light yellow to clear. Dark color indicates dehydration.
Headaches and Fatigue
Dehydration can cause headaches and make you feel tired.
Dry Mouth and Lips
Feeling thirsty and having dry lips are early signs of dehydration.
Hydration Calculator for Your Goal
Prefilled calculators for specific audiences — pick yours and get a target tuned to your situation
Nursing a baby? The breastfeeding water intake calculator adds your milk-production needs at every stage.
Training for a race? The hydration calculator for runners pairs your daily target with before, during, and after-run drinking guidance.
Wondering about your child? The daily water intake calculator for kids uses age-based targets from age 4 up.