Water Intake Calculator
Enter your weight, activity level, and climate to see an estimated daily water intake in liters and cups.
Enter your weight to see your estimated daily water intake.
General estimate only — needs vary with age, health, pregnancy, and medication. Calculated on your device; nothing is sent anywhere.
How it works
- Enter your body weight in kilograms or pounds — the toggle converts nothing, it just switches which unit you type in.
- Pick how often you exercise and the climate you live in from the two dropdowns.
- Read your estimated daily intake in liters, cups, and ounces below — it updates as you change any input.
Frequently asked questions
- How is my daily water intake calculated?
- The estimate starts from a widely used baseline of about 33 milliliters per kilogram of body weight, roughly half an ounce per pound. It then adds up to one liter for regular exercise and up to 0.75 liters for hot or humid climates, since sweat losses rise with both.
- Does coffee, tea, or food count toward my water intake?
- Yes. Caffeinated drinks are only mildly diuretic and still contribute net fluid, and milk and juice count fully. Food typically supplies around 20 percent of total fluid — fruit, vegetables, soups, and yogurt are mostly water — so the number shown does not have to come from plain water alone.
- How accurate is this water intake estimate?
- It is a reasonable starting point, not a prescription. Individual needs vary with age, diet, medications, pregnancy, breastfeeding, and health conditions such as kidney or heart disease. The most reliable everyday signals remain thirst and urine color — pale yellow generally means you are drinking enough.
- Is it possible to drink too much water?
- Yes, though it is rare. Drinking several liters in a short window can dilute blood sodium, a condition called hyponatremia, which is dangerous. Spread intake across the day, drink to thirst during long exercise, and do not force large volumes because a calculator suggested a target.
- Is my weight or health data sent to a server?
- No. The calculation is a few arithmetic operations that run entirely in your browser, with no network requests. Nothing you enter is uploaded, stored, or logged, and the calculator keeps working offline once the page has loaded.
About this tool
This water intake calculator estimates how much fluid you should aim for in a day, based on your body weight, how active you are, and the climate you live in. The result appears in liters, US cups, and fluid ounces, and it updates live as you type — no signup and no steps beyond three inputs.
The math follows the common per-weight heuristic used by dietitians as a first approximation: roughly 33 ml of fluid per kilogram of body weight per day. On top of that baseline, the calculator adds an allowance for exercise — sweat losses during a vigorous hour can exceed a liter — and another for hot or humid conditions, where you lose fluid even at rest. Everything runs client-side in your browser: weight is health data, so there are no network requests, and nothing you enter is stored or transmitted.
The target covers total fluid, not just plain water. Tea, coffee, milk, and juice all count, and about a fifth of a typical day’s fluid arrives through food — cucumbers, oranges, soup, and yogurt are mostly water. That matters in practice: someone with a 2.5-liter estimate who eats normally and drinks a few cups of tea may only need around 1.5 liters of actual water to close the gap.
A few practical tips. Spread intake across the day rather than catching up in the evening, since large boluses are mostly excreted. Keep a bottle visible on your desk — availability drives consumption more than willpower does. During long workouts or heat waves, drink to thirst and consider electrolytes if a session runs past an hour. And treat the number here as a starting point: age, medications, pregnancy, and kidney or heart conditions all change fluid needs, so ask a doctor if any of those apply to you.