Daily Water Intake Estimator
Quick litres-per-day estimate from weight, activity and climate. Free, private and instant.
How to use the Water Intake Estimator
- Pick metric (cm, kg) or imperial (ft, in, lb) units.
- Enter weight.
- Choose activity level: Low (mostly sitting), Moderate (regular walking or exercise) or High (daily hard training or physical job).
- Choose climate: Temperate, Hot and humid (e.g. Bangladesh summer) or Very hot.
- Press Calculate to get an instant result with a colour scale, chart and plain-English explanation.
About the Water Intake Estimator
This quick estimator tells you how much water to drink a day from your weight, activity level and climate. It uses about 33 ml per kg of body weight and adds extra for exercise and heat, which matters in hot, humid countries like Bangladesh.
Also known as: water intake calculator, how much water should I drink, hydration calculator, water per day by weight.
Worked example
- Weight: 70 kg
- Activity level: Moderate (regular walking or exercise)
- Climate: Temperate
Daily water target: 2.7 litres (11 glasses of 250 ml). Aim for about 2.7 litres (90 fl oz) of fluids a day, spread out through the day.
- Litres per day: 2.66
- Glasses (250 ml): 10.6
- Bottles (500 ml): 5.3
- Fluid ounces: 90
Formula and cut-offs
Water (ml) = body weight (kg) x 33 + activity add-on (0, 350 or 700 ml) + climate add-on (0, 500 or 1,000 ml). About 80% comes from drinks and 20% from food.
Frequently asked questions
How much water should I drink a day?
Many adults need about 2 to 3 litres of total fluid a day. Needs rise with body weight, exercise and heat.
Does tea or coffee count?
Yes. Tea, coffee, milk and soups count toward fluid intake, though plain water is best.
Can you drink too much water?
Yes. Drinking far more than you need, very quickly, can lower blood sodium. Spread intake through the day.
What is the daily water target for a weight of 70 kg?
Daily water target: 2.7 litres (11 glasses of 250 ml). Aim for about 2.7 litres (90 fl oz) of fluids a day, spread out through the day. Enter your own numbers above for a personal result.
Sources and references
- World Health Organization - Healthy diet fact sheet
- National Academies - Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate
Written and checked by the MediHub editorial team against the sources above. Read how we build and review our calculators.
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Last updated . This calculator is for education only and is not medical advice. See the medical disclaimer.