What is the Water Intake Calculator?
The water intake calculator is a free online tool that helps you work out water intake quickly and accurately. It uses the standard formula Base = 35 ml x weight(kg) + activity adjustment and shows the result instantly as you type, along with a full breakdown so you can see exactly how the answer was reached.
How to use this calculator
- Enter your weight.
- Select your activity level.
- See your daily water target.
Formula used
Base = 35 ml x weight(kg) + activity adjustmentExplanation of each input
- Weight (kg) โ the weight used in the calculation.
- Activity โ the activity used in the calculation.
Understanding your result
- Recommended water โ the calculated recommended water in litres/day.
- Glasses (250 ml) โ the calculated glasses (250 ml).
Step-by-step calculation
For the example values 70kg, moderate:
- Apply the formula:
Base = 35 ml x weight(kg) + activity adjustment - Substitute the values: 35x70 + 350
- Result: about 2.8 litres/day
Worked example
| Inputs | 70kg, moderate |
|---|---|
| Working | 35x70 + 350 |
| Result | about 2.8 litres/day |
Benefits and practical uses
This calculator saves you time and reduces errors when you need water intake. It is useful for students, professionals and anyone who wants a fast, reliable answer without manual calculation. Results update instantly, work in your browser and can be copied or shared in one click.
Assumptions and limitations
- 35 ml/kg guideline.
- Adjust for climate, pregnancy and medical advice.
Frequently asked questions
Does this include water from food?
No. About 20% of fluid comes from food, so individual needs vary with climate and health.
Disclaimer: This calculator provides general estimates for educational purposes only and is not medical advice. Consult a qualified healthcare professional for personal guidance.