Base amount
body weight (kg) × 30 ml
Daily Water Intake Calculator — How Much Should You Drink?
Calculate your optimal daily water intake based on weight, activity level, and temperature. Includes caffeine and alcohol dehydration offsets.
Daily Water Intake Calculator
Hydration
Calculate your optimal daily water intake based on weight, activity level, and temperature.
Total Recommended
2600ml
11 cups (250ml each)
Base1950 ml
Activity Bonus+350 ml
Temperature Bonus+150 ml
Diuretic Offset+150 ml
Hydration needs change with body weight, activity, heat, and drink habits
This calculator starts with body weight, then adds water for activity, warmer temperatures, coffee, and alcohol. The result is shown in milliliters and 250 ml cups so it is easier to spread intake across the day.
Calculation basics
Environment
activity +0/+350/+700 ml; temperature +0/+150/+350 ml
Diuretic offset
coffee +150 ml per cup; alcohol +200 ml per drink
How to use
- Enter your body weight.
- Select today's activity level and temperature range.
- Add coffee and alcohol intake, then spread the recommended ml or cup count through the day.
Frequently asked questions
Is more water always better?
No. Kidney disease, heart failure, and low sodium risk can make excess fluid unsafe.
Does coffee always dehydrate you?
Regular coffee also contributes fluid, but this tool uses a conservative offset because caffeine can increase urine output for some people.
How should I handle exercise days?
Choose a higher activity level on sweaty days and consider electrolytes for long or intense sessions.
How do I recognise dehydration?
Urine colour is the most practical signal: pale straw usually means you are fine, while dark yellow or brownish means you are behind. Dry mouth, headache, tiring earlier than usual, and urinating less often point the same way. Thirst is a late signal — it arrives after you are already short.
Results are general estimates and are not a substitute for professional medical advice.