Water Intake Calculator
Estimate how much water to drink each day based on your weight, exercise time and whether the weather is hot.
Your day
Adds ~5 ml/kg to your daily target.
A simple hydration framework
Most adults do well aiming for around 35 ml of water per kg of bodyweight, plus an extra ~12 ml/kg for every hour of training and a small bump in hot weather. Spread it across the day, and let thirst and urine colour fine-tune the target.
What your hydration target means
The suggested daily water intake is a starting estimate based on your body weight and activity level. It covers total fluid — plain water, tea, coffee and water-rich foods all count.
Thirst, urine colour (aim for pale straw) and energy levels are still the most reliable day-to-day signals. Use the number as a target, not a rule.
When to use the water intake calculator
It's most useful when you're increasing training volume, spending time in a hot or dry climate, or noticing symptoms of under-hydration such as headaches or dark urine.
Athletes and people on very high-sodium diets may need more; those with certain medical conditions may need less. When in doubt, ask your doctor before changing intake dramatically.
Frequently asked questions
Where does 35 ml/kg come from?+
It's a well-cited baseline for sedentary adults in temperate climates. We add extra fluid for training (12 ml/kg per hour of exercise) and hot weather.
Do tea and coffee count?+
Yes. Almost all fluids contribute to your daily total, including coffee, tea, milk and water-rich foods like fruit.
Can I drink too much water?+
Yes — hyponatraemia is real but rare in healthy adults. Sip across the day rather than chugging litres at once.
Does the target change if I'm cutting calories?+
Hydration needs are based mostly on weight and activity, not calories. Maintain your usual intake while dieting.
Health disclaimer: Caloritix provides estimate-based health and fitness calculators for general educational purposes only. Results are not medical advice and should not replace guidance from a qualified healthcare professional.