Free Online Water Intake Calculator, How Much Water to Drink a Day
Get a daily water target from your body weight. Enter your weight, add the minutes you exercise and how warm your climate is, and it gives a target in litres, millilitres, cups and fluid ounces. The figure is a general guide, not a medical rule, and the page notes that food, drinks and your own thirst all count towards it too.
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Water Intake CalculatorA daily water target from your weight, exercise and climate.
Everything is worked out in your browser. No number you type is sent anywhere, and there is no account.
You and your day
Nothing is uploaded; every number stays in your browser.
kg
lb
min
Minutes of activity that makes you sweat. Leave at zero for a rest day.
Result
The save button in the top bar keeps the numbers you have filled in, on this device only.
Units and numbers
Display
Size
Theme
Full screen hides the page around the tool. Press Escape, or the button in the bar, to come back.
History
Your data
Settings, history and saved setups live in this browser and nowhere else. There is no account and no server, which also means clearing them here is final.
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The baseline is your body weight: bigger bodies need more water, and a common guide is around
thirty-three millilitres per kilogram a day. Exercise adds to it, roughly a few hundred millilitres
for every half hour that makes you sweat, and a warm or humid climate raises the whole figure,
because you lose more through your skin and breath.
Food and other drinks count too. Fruit, vegetables, soup, tea, coffee and milk all carry
water, and together they cover a fair slice of the total. So the figure here is your whole daily
water, not a target of plain water to drink on top of everything else. Most people need less
straight water than the number suggests.
Your body is the better gauge. Thirst, and pale rather than dark urine, track hydration
more usefully day to day than any formula. Some situations change the amount a lot, including
pregnancy, heavy sweating, illness and certain kidney or heart conditions, so treat this as a
starting point and follow medical advice where it applies.
Where Your Input Goes
Nowhere. And you can check that yourself.
Your weight is worked out in your browser and never sent anywhere.
It is all done by your own browser. Press F12, open the Network tab, and use the tool:
the page fetches its own code and nothing else. Or load the page, turn off your wifi, and
carry on. It still runs, because there was never a server in the middle.
How to Work Out Your Water Intake
A few steps, and nothing is uploaded.
1
Enter your weightIn kilograms or pounds. It sets the baseline. Nothing is uploaded.
2
Add exercise minutesTime spent active enough to sweat; leave at zero on a rest day.
3
Pick your climateTemperate, warm, or hot and humid, which raises the whole figure.
4
Read the targetYour daily water in litres, cups, millilitres and fluid ounces.
What to Know About Water Intake
Including the things this tool cannot do.
The baseline is your body weight. A common guide is about thirty-three millilitres per kilogram a day, so heavier bodies need more. This tool starts there, then adds for exercise and climate. It is a rule of thumb, not a precise requirement, and people in the same body vary.
Food and drinks count towards it. Fruit, vegetables, soup, tea, coffee and milk all carry water, and together they cover a good part of the total. The figure here is your whole daily water, not plain water to drink on top of your meals, so the amount you actively sip is usually less.
Exercise and heat raise the need. Sweating loses water fast, so activity adds a few hundred millilitres per half hour, and a hot or humid day lifts the whole figure. On a long or intense session, drink to thirst throughout rather than saving it all for afterwards.
Your body is the best day-to-day gauge. Thirst and pale urine track hydration better than any number. Some situations change the amount a lot, including pregnancy, illness, heavy sweating and certain kidney or heart conditions, so treat this as a guide and follow medical advice where it applies.
Key Features & Capabilities
What this tool does, and what it deliberately does not.
A weight-based targetA daily baseline from your body weight.
Exercise and climateMore for time spent sweating and for a warm climate.
Litres, cups or ouncesThe figure shown in every common unit at once.
As you typeThe target updates while you edit, with no run button.
History and savedRecent results and named setups, on this device only.
Nothing uploadedYour weight stays in the browser.
About the Water Intake Calculator
How much water to drink is one of the most asked and most over-answered health questions. The old eight glasses rule was never based on much; a better estimate scales with your body and your day. This calculator starts from your weight, adds for the exercise you have done and the warmth of your climate, and gives a daily target in litres, cups, millilitres and fluid ounces.
It is important to read the number the right way. It is your total daily water, and a large share of that comes from food and from drinks like tea, coffee and milk, so the amount of plain water you actually need to sip is smaller than the figure looks. Exercise and heat push the total up because you lose more through sweat and breath.
This is general guidance, not a medical rule, and it runs entirely in your browser with nothing uploaded. Your own thirst and the colour of your urine are more reliable day-to-day signals than any formula, and several situations, including pregnancy, illness and some kidney or heart conditions, change the right amount considerably. Where those apply, follow the advice of a professional over a calculator.
Frequently Asked Questions
Where the target comes from, and what counts towards it.
From your body weight as a baseline, about thirty-three millilitres per kilogram a day, plus an allowance for exercise, roughly a few hundred millilitres per half hour of sweating, and a rise for a warm or humid climate. The result is your whole daily water, shown in several units.
No. Food, and drinks like tea, coffee, milk and juice, all count towards the total, and together they cover a good part of it. So the amount of plain water you actually need to drink is usually less than the figure shown.
Not in normal amounts. The mild diuretic effect of caffeine is more than offset by the water in the drink, so tea and coffee count towards your daily total for most people. Very large amounts of caffeine are a different matter.
No. Drinking far beyond your needs offers no benefit and, in rare extreme cases, can be harmful by diluting blood sodium. Let thirst and pale urine guide you, and do not force large amounts well past the target.
No. Your weight and activity go into the sum in this tab and nowhere else. Saved setups stay in this browser, and the page works with the connection off.
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