Water intake calculator
How much to drink each day, from your weight.
Examples temporarily replace the input and settings. You can restore your previous work.
Output
Enter your weight.
Your files stay on your device
This tool runs entirely in your browser. What you paste is processed on your device and is never sent to a server, so it is safe to use with tokens, keys and unpublished text.
Example
Worked example — Water intake calculator
Use the following inputs and settings. Keep other settings at the page defaults.
| Item | Value |
|---|---|
| Units | Metric (cm, kg) |
| Weight | 70 |
| Exercise a day | 30 minutes |
| Weather | Mild |
| Output | Water to drink: 2.5 L a day |
| Output | About 10 glasses of 250 mL · 85 US fl oz |
| Output | How it adds up: 70 kg × 30 mL per kg = 2.1 L · 30 min of exercise +0.35 L |
| Output | About 20% of the water you need comes from food; the amount above is for drinks. |
| Output | For healthy adults. With a heart or kidney condition, or if pregnant or breast-feeding, follow your doctor’s advice. |
Expected result — Water to drink: 2.5 L a day
How it works
- Enter your weight in kg or lb.
- Choose how long you exercise on a typical day and whether it is hot.
- Read how much to drink in litres, in 250 mL glasses and in ounces, with how it adds up.
Frequently asked questions
- How is it worked out?
- 30 mL for each kg of body weight, kept between 1.5 and 3 litres, plus 350 mL for every 30 minutes of exercise and half a litre in hot weather. A 70 kg person who exercises 30 minutes a day gets 2.5 L — about 10 glasses.
- Does it include food?
- No — it is what to drink. Food supplies roughly a fifth of the water you need on top.
- Where do the numbers come from?
- They sit between the European (EFSA) and U.S. (National Academies) reference intakes for adults, and the sweat lost in exercise from sports-medicine guidance.
- Is it right for everyone?
- It is for healthy adults. With a heart or kidney condition, or when pregnant or breast-feeding, follow your doctor’s advice. Thirst and pale urine are good everyday guides.
- Is anything saved?
- No. It is worked out in your browser.