Calculators
Water Intake Calculator
Estimate daily water intake from body weight, exercise and climate, as litres and glasses.
- Runs in your browser
- Nothing uploaded
The tool
Enter your numbers below. Results update as you type, and nothing leaves your browser.
Everything you enter stays on your own machine. Nothing is sent to us or to anyone else, which you can confirm in your browser network tab.
What people use it for
- Setting a daily water goal
- Planning hydration for training
- Workplace wellbeing programmes
- Hot-weather planning
About this tool
What the Water Intake Calculator does
Fluid needs vary with body size, activity and climate. A common planning estimate is about 30 to 35 ml per kg of body weight per day, plus roughly 500 ml for every 30 minutes of exercise and more in hot weather. Food provides part of daily water intake.
It also works as a hydration calculator.
Formula
- Fluid (ml) = weight × base ml per kg + 500 ml per 30 minutes of exercise + 500 ml in heat
Worked example
Using the starting values in the calculator above:
| Input | Value |
|---|---|
| Body weight | 75 kg |
| Base intake per kg | 33 ml |
| Exercise per day | 45 minutes |
| Hot climate or heavy sweating | No |
| Result | Value |
|---|---|
| Daily fluid | 3.2 |
| Glasses (250 ml) | 12.9 |
| Fluid ounces | 109 |
How to read the result
Pale yellow urine is a simple sign of adequate hydration.
People with heart or kidney conditions may need to limit fluids; follow medical advice.
General information, not medical advice. Speak to a qualified health professional before making changes to diet, exercise or treatment.
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Questions
Questions about this tool
The things clients actually want to know — costs, timelines, ownership and what happens after launch.
It varies; many adults need roughly 2 to 3 litres of total fluid, more with exercise and heat.
Yes, moderate coffee and tea contribute to fluid intake.
Yes. Very large amounts in a short time can cause dangerously low sodium.
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