Daily Water Intake Calculator
Calculate how much water you should drink per day based on your weight, activity level, and climate.
About this calculator
The Daily Water Intake Calculator builds your target from three pieces: a base of 33 ml per kilogram of body weight, an extra amount for how active you are, and a fixed addition for hot or humid weather. It then breaks the total into a suggested schedule through the day.
The schedule matters because water works best when sipped steadily. The plan puts the most in the middle of the day and tapers toward the evening so that sleep is not interrupted.
How to use it
- Enter your Weight and choose kg or lbs.
- Choose your Activity Level and Climate.
- Press Calculate Water Intake.
- Read the total, the breakdown and the drinking schedule.
How the total is built
Base = Weight(kg) × 33 ml. Activity adjustment = Base × (factor − 1). Climate adjustment = 0, 200, 400 or 600 ml. Total = Base + Activity + Climate. The schedule splits the total across five periods of the day.
Worked example
70 kg, active, warm climate
| Base requirement | 2,310 ml |
| Activity adjustment | 693 ml |
| Climate adjustment | 200 ml |
| Total | 3,203 ml (3.20 litres) |
| Glasses of 250 ml | 13 |
This tool gives general information, not medical advice. Talk to a doctor or dietitian before making changes to your diet, exercise or medication.
Tips and common mistakes
- Front-load: drink a glass soon after waking.
- Carry a bottle and refill it at set times.
- Add a pinch of salt and sugar or an electrolyte drink during long, sweaty sessions.
- Count the water in food and other drinks to avoid over-drinking.
- Reduce the amount if your doctor limits fluids.
Frequently asked questions
How much water should I drink per kg of body weight?
About 30 to 35 ml per kg per day.
Do I need more water in summer?
Yes, hot weather can add half a litre or more.
How much water should I drink during exercise?
About 150 to 250 ml every 15 to 20 minutes during longer sessions.
Does the schedule need to be exact?
No, it is a guide to spread intake.
Is the total all from plain water?
No, other drinks and food contribute.
Is the result suitable for pregnancy?
Needs are higher in pregnancy and breastfeeding. Ask your doctor.