Food & nutrition calculators
Water intake calculator
Make a rough planning estimate of daily fluid from body weight and activity level.
Runs in your browser with no account and no stored data
How it works
Enter your body weight in kilograms and select your activity level. The tool estimates your daily water needs in litres and glasses.
Base: 35 ml per kg of body weight. Adjustments: moderate activity +0.5 L, active +1.0 L, very active +1.5 L.
70 kg person with moderate activity → (70 × 0.035) + 0.5 = 2.45 + 0.5 = about 2.95 L per day.
Checking hydration targets, adjusting water intake around exercise, or building healthier daily habits.
This is a broad planning estimate, not medical advice. Climate, pregnancy, medication, illness, exercise, and medical conditions can change fluid needs. Follow any fluid restriction or hydration advice given by a qualified healthcare professional.
What do you want to do next?
Want to work out your protein needs too? The protein calculator gives a daily gram target.
FAQ
Is this medical advice?+
No. This is a general estimate based on common guidelines. Speak to a doctor if you have a specific health condition that affects hydration needs.
Does this include water from food?+
No. The estimate covers drinking water. About 20 percent of daily water intake typically comes from food, so your actual drinking target may be slightly lower.
Should I drink more when it is hot?+
Yes. Heat and humidity increase fluid loss through sweat. The activity adjustment in this calculator partially accounts for this, but on very hot days add an extra glass or two.
Is it possible to drink too much water?+
Yes, though it is rare for healthy adults under normal conditions. If you are an athlete or exercising intensively, balance water with electrolytes.