Find out exactly how much water you should drink each day — personalised to your weight, activity level, and climate, with results in litres, ounces, and glasses.
The Water Intake Calculator gives you a personalised daily hydration target based on your body weight, activity level, and climate. Rather than the generic "8 glasses a day" rule, it uses a weight-proportional formula with activity and climate adjustments to produce a recommendation that accounts for your actual fluid losses. Results are shown in litres, fluid ounces, and standard glasses so you can use whatever unit is easiest to track.
No tutorials. No learning curve. Open it and get started.
Runs in your browser. All calculations happen locally — no personal data (weight, activity level) is sent to any server.
Completely free. No trial period. No premium tier for basic functionality. No account required.
One job, done well. The Water Intake Calculator was built to solve a specific problem cleanly. No feature bloat, no ads, no distractions — just a fast, personalised hydration recommendation.
How is my recommended water intake calculated?
The calculator uses your body weight as a baseline (typically 30–35ml per kg), then applies multipliers for activity level and climate. Active individuals and those in hot climates need significantly more water to replace losses through sweat.
Does the result include water from food?
The result represents total fluid intake from drinks. Food contributes roughly 20% of daily water intake, so if you eat a lot of water-rich foods (fruits, vegetables, soups), your drink requirement may be slightly lower.
How does activity level affect the recommendation?
Light activity adds a moderate increase to the baseline. Moderate exercise (30–60 min daily) adds around 500ml. Intense exercise or heavy physical labour can increase requirements by 1–2 litres or more depending on sweat rate.
Why does climate affect how much water I need?
Hot or humid climates increase sweat rate even at rest, raising your fluid requirements. The calculator adds an allowance for hot climates and reduces it slightly for cool climates where sweat losses are lower.
Is the result shown in litres, ounces, and glasses?
Yes. The calculator displays your recommended daily intake in litres, US fluid ounces, and an equivalent number of standard glasses (250ml each), so you can use whichever unit is easiest to track throughout the day.