Fluid Intake Calculator
Work out your daily fluid needs from body weight, activity level and outdoor temperature, in litres and 250 ml glasses, split across the day.
Note: These calculations are for informational purposes only and do not replace professional tax or financial advice. All information without guarantee.
FAQ
Frequently Asked Questions
How much water should I drink per day?
The German Nutrition Society recommends about 1.5 liters of water per day for adults. Total fluid needs (including food) are about 35 ml per kg of body weight. More is needed during exercise or hot weather.
What counts toward my daily fluid intake?
Water, unsweetened tea, and diluted juice spritzers are ideal. Coffee counts too, despite the myth. Fruits and vegetables also contribute significantly. Avoid sweetened drinks and excessive alcohol.
Does this calculator replace a doctor visit?
No. This calculator provides general orientation only. For medical questions, or before starting a diet, therapy or treatment, always consult a qualified physician or therapist.
Guide
What is the Fluid Intake Calculator?
The fluid intake calculator computes the recommended daily drinking amount based on body weight, age and activity.
How does the Fluid Intake Calculator work?
Enter weight, age and activity level. The calculator determines the base requirement (approx. 30-35 ml per kg body weight) and adds supplements for exercise, heat or illness.
Key Data and Facts
Recommended: 30-35 ml per kg body weight/day. German Nutrition Society recommendation: approx. 1.5 litres of drinking (plus fluid from food). During sport: approx. 0.5-1 l extra per hour.
Step-by-Step Guide
How to calculate your daily fluid requirement step by step: 1. Enter your body weight: The basic requirement is about 30-35 ml per kg of body weight. 2. Take age into account: Older people have a reduced sense of thirst but should drink at least 1.5 litres daily. Children need relatively more fluid per kg. 3. Specify your activity level: With sport, about 0.5-1.0 litres extra per hour of intense exertion. 4. Environmental conditions: In heat (over 30 degrees) or dry air (heated rooms in winter) the requirement rises by 0.5-1.0 litres. 5. Special circumstances: Fever increases the requirement by about 0.5 litres per degree above 37 degrees. Pregnancy: about 300 ml extra. Breastfeeding: about 600-700 ml extra. 6. DGE recommendation: About 1.5 litres through beverages (water, tea, juice) plus about 0.9 litres through food. Optimal beverages: water, unsweetened tea, diluted juices.
Calculation Example
Person, 75 kg, light activity: base requirement = 75 x 33 ml = 2,475 ml (approx. 2.5 litres total). Of this, about 1.6 litres as drinking fluids, the rest from food.
Sources
Official sources
Calculations are based on applicable German laws and official data:
Full methodology at Methodology.
Reviewed by Konstantin Iakovlev · Last updated:
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