Calculation results
Recommended water intake:
Of which through fluids:
Daily Water Intake Calculator
What This Calculator Does
A healthy hydration habit begins with a realistic daily target, and that number is different for every person. This calculator estimates how much water you should drink each day based on your body weight, age, and lifestyle details. It works for anyone who wants a practical starting point: busy office workers, gym enthusiasts, outdoor runners, pregnant mothers, and seniors who tend to under-drink. Instead of repeating the vague eight glasses advice, you get a figure matched to your own frame.
How the Estimate Is Calculated
The method is refreshingly simple. A widely used baseline recommends about 30 to 35 millilitres of water per kilogram of body weight every day, which matches roughly half an ounce per pound. Intense training typically adds 350 to 500 ml for every 30 minutes on the move, since sweat carries away far more than we notice.
Take a 70 kg adult as a worked example. Multiplying 70 by 30 to 35 gives a baseline of 2.1 to 2.5 litres per day. Adding one hour of training plus a hot afternoon pushes a sensible total to about 3 litres, which is why athletes carry larger bottles.
How to Use It and Get Better Results
Switch between Imperial and Metric at the top, then fill in Age, Height, and Weight in the labelled fields. Choose Male or Female so results can be fine tuned, and press Calculate. Your suggested daily figure appears immediately, ready to compare with what you actually drink now.
Treat the answer as a target zone, not a rigid rule. Drink extra in heat, during illness, or while breastfeeding, and let pale straw coloured urine confirm you are on track. Keeping a filled bottle within reach turns the number into a habit, not a chore.
Frequently Asked Questions
How much water should I drink daily?
Most adults need about 30 to 35 ml per kg of body weight. A 70 kg person therefore needs roughly 2.1 to 2.5 litres daily, plus extra for exercise or hot weather.
Does coffee or tea count toward intake?
Yes, moderate caffeine drinks hydrate you and count toward your daily total. Just remember sugary or alcoholic drinks bring extra calories, so plain water should still fill most of your 2 to 3 litre goal.
Can I drink too much water?
Yes. Drinking several litres within a couple of hours can dilute blood sodium, a dangerous condition called hyponatraemia. Spread your daily target, around 2 to 3 litres for most adults, across the whole day.
Do I need extra water when exercising?
Definitely. Add roughly 350 to 500 ml for every 30 minutes of intense activity, since sweat losses can easily exceed one litre per hour in heat.
Should intake change as I age?
Older adults often feel less thirsty yet still need 30 to 35 ml per kg. A 60 kg senior should aim near 1.8 to 2.1 litres daily, so scheduled sipping helps.