Water Intake Calculator — Daily Hydration

What the water intake calculator does

Hydration affects energy, focus, digestion, temperature regulation, and physical performance. This calculator estimates how much fluid you should aim to drink each day based on your body weight, daily exercise, and the climate you live in, then expresses it in litres, cups, and fluid ounces.

How the calculation works

It starts from a baseline of roughly 33 ml of water per kilogram of body weight, a widely used rule of thumb for adults. It then adds extra fluid for exercise — about 350 ml for each 30 minutes of activity — and applies a multiplier for warm or hot, humid conditions where you lose more water through sweat.

How to interpret your result

The figure is a target for total daily fluid, much of which can come from food and other drinks. A simple real-world check is urine colour: pale straw indicates good hydration, while dark yellow suggests you need more. Thirst is a useful but lagging signal, so sip regularly rather than waiting until you feel parched.

Health recommendations

Spread intake across the day, drink more around workouts and in the heat, and increase fluids if you are ill, pregnant, or breastfeeding. People with kidney or heart conditions should follow medical advice on fluid limits rather than general guidelines.