Water Intake Calculator
Get a daily water guideline from your body weight, how long you exercise and how hot it is. The result shows how much to drink and how that compares with the European reference values.
Your results
| Glasses of 250 ml | 10 |
| EFSA reference for adults | 2.5 L |
A general guideline for healthy adults, not medical advice. Kidney, heart or liver conditions, pregnancy and some medicines change fluid needs, so follow your doctor's advice.
How it works
- 1We start from about 35 ml per kg of body weight, a common rule of thumb for healthy adults.
- 2We add about 350 ml for every 30 minutes of exercise and 500 ml for hot or humid weather.
- 3Around 20% of daily water comes from food, so the drink target is about 80% of the total.
Daily water by body weight
Total water and the share to drink (about 80%), without exercise and with 60 minutes of exercise, from the same formula as the calculator.
| Body weight | Drinks, rest day | Drinks, 60 min exercise |
|---|---|---|
| 50 kg (110 lb) | 1.4 L | 2.0 L |
| 60 kg (132 lb) | 1.7 L | 2.2 L |
| 70 kg (154 lb) | 2.0 L | 2.5 L |
| 80 kg (176 lb) | 2.2 L | 2.8 L |
| 90 kg (198 lb) | 2.5 L | 3.1 L |
| 100 kg (220 lb) | 2.8 L | 3.4 L |
Where these numbers come from
The European Food Safety Authority sets adequate total water intakes of 2.0 litres a day for women and 2.5 litres for men, with about 20% normally coming from food; the US National Academies give higher figures of 2.7 and 3.7 litres. The exercise allowance follows the American College of Sports Medicine guidance on fluid replacement. This is a general guideline, not medical advice.
Frequently asked questions
How much water should I drink a day?
Most healthy adults need about 2-2.5 litres of total water a day, of which roughly 1.6-2 litres come from drinks. Body size, exercise and heat push that up.
How much water should I drink based on my weight?
A simple guideline is about 35 ml per kg of body weight in total water. For 70 kg that is about 2.5 litres, around 2 litres of it as drinks.
How much extra water do I need when I exercise?
Roughly 350 ml per 30 minutes is a sensible average, but sweat rates range widely. Weighing yourself before and after training shows your own losses.
Do coffee and tea count toward water intake?
Yes. Coffee, tea, milk and other drinks all count, and so does water in food such as fruit, vegetables and soups.
Using the result
What the number is
A daily target range for a healthy adult, scaled to your body weight and to the inputs that change it, such as your goal, exercise or climate. It comes from published reference values, not from a measurement of your body.
How to use it
Spread the amount across the day instead of getting it all at once, and aim to land in the range on most days rather than hitting an exact number. Give it two to three weeks before you judge how it works for you.
When to stop guessing
If you hit the target and still struggle with energy, recovery or progress, the answer usually sits in the whole plan: food, training and sleep together. A coach on Trainera looks at all three.
What this calculator cannot know
This calculator works from body weight and a few facts about your day, nothing else. It does not know your kidney function, your medication, how much you sweat or how much you already get from food and other drinks. Children, pregnant and breastfeeding women and anyone with kidney, heart or liver disease should get their target from a doctor or dietitian. Nothing here is medical advice.
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Turn these numbers into a real plan
Train on your own with Trainera's free workout and diet tracker, or get matched with a certified personal trainer who builds your plan around these numbers.