Daily Water Intake Calculator
Find out exactly how much water you should drink each day based on your weight, activity level, and climate
Your Daily Water Intake
Enter your weight and activity level, then click Calculate.
General Daily Water Recommendations (WHO / NHS)
| Group | Min. Daily (litres) | Notes |
|---|---|---|
| Adult men | 2.5 L | Total fluid intake including food |
| Adult women | 2.0 L | Total fluid intake including food |
| Pregnant women | 2.3 L | Increased needs for fetal development |
| Breastfeeding women | 2.7 L | To replace fluid lost in milk |
| Athletes (moderate) | 3.0–4.0 L | Depends on sweat loss |
| Hot climate | +0.5–1.0 L | Additional to baseline |
Frequently Asked Questions
The commonly cited "8 glasses a day" (about 2 litres) is a rough guideline. The actual amount depends on body weight, activity level, climate, diet, and health status. A more accurate formula is 30–35 ml per kg of body weight, adjusted upward for exercise and hot weather.
Yes, caffeinated drinks like coffee and tea do contribute to fluid intake, though slightly less efficiently than water. Modern research shows that moderate coffee consumption does not cause net dehydration. About 20% of daily water also comes from food, especially fruits and vegetables.
Common dehydration signs include dark yellow urine, dry mouth, headache, fatigue, dizziness, and reduced urine output. A simple rule: your urine should be pale yellow or clear. Thirst itself is a late signal — aim to drink before you feel thirsty.
Yes. Overhydration (hyponatremia) is rare but can occur, especially in endurance athletes who drink excessive plain water. Symptoms include nausea, headache, confusion, and in severe cases, seizures. Healthy kidneys can process about 0.8–1 litre per hour, so spreading intake throughout the day is ideal.
The American College of Sports Medicine recommends drinking 500 ml (about 2 cups) 2 hours before exercise, sipping during exercise, and replacing fluids after. For every hour of moderate exercise, add approximately 500 ml to 1 litre of water to your daily intake.
About This Water Intake Calculator
This free Daily Water Intake Calculator uses a personalised formula based on your body weight (30–35 ml/kg), adjusted for activity level and climate. It also factors in pregnancy and breastfeeding. Results show your recommended daily water in litres and glasses.
Water by Weight (Moderate Activity)
| Weight | Water/Day | Glasses |
|---|---|---|
| 50 kg | 1.98 L | ~8 |
| 60 kg | 2.38 L | ~10 |
| 70 kg | 2.77 L | ~12 |
| 80 kg | 3.17 L | ~13 |
| 90 kg | 3.56 L | ~15 |
| 100 kg | 3.96 L | ~17 |
Hydration Tips
- Drink a glass of water first thing in the morning
- Carry a reusable water bottle throughout the day
- Drink a glass before each meal
- Set hourly reminders if you forget to drink
- Eat water-rich foods (cucumber, watermelon, oranges)
- Monitor urine colour — pale yellow = well hydrated
