Water Intake Calculator
Find how much water to drink per day, based on your body weight and activity level. Get the amount in litres and cups.
How Much Water Do You Need a Day?
Your water need is not a fixed number. It scales with your body size and how much you move. A bigger body and more activity both raise the amount of fluid you lose, so they raise the amount you need to take in.
A practical guide is about 30 to 45 ml of water per kilogram of body weight a day. The light end fits a quiet day at a desk. The high end fits hard training or a hot climate. This calculator turns your weight into a clear daily target in litres and cups.
How This Water Calculator Works
Enter your weight and pick an activity level. The tool multiplies your weight in kilograms by a millilitres-per-kilogram value for that level. Sedentary uses 30 ml/kg, lightly active 35, moderately active 40, and very active 45.
It then shows your daily total in litres, in millilitres, and in 240 ml cups, with a table for every activity level so you can see how training changes the number.
Validated example: a 70 kg person who is moderately active gets 2.8 litres a day, which is about 2,800 ml or 12 cups.
Signs of Good Hydration
The simplest check is your urine. Pale yellow most of the day means you are drinking enough. Dark yellow means you are behind and should drink more. Strong thirst, a dry mouth, headaches or low energy can all point to mild dehydration.
You lose more fluid on hot days, at altitude, and during long or intense exercise. On those days, push toward the higher end of your range. Your energy use rises too, so it helps to know your daily calories and your TDEE when activity climbs.
Tips to Drink More Water
Knowing the number is the easy part. The habit is the work. Start the day with a glass of water. Keep a bottle in sight at your desk. Drink a glass before each meal. Flavour water with lemon or mint if plain water bores you.
Build it into routines you already have, then track whether it sticks. The Velpa app logs your steps and weight in one private place, so you can watch your daily habits add up over time. This page is general information, not medical advice. If you have a condition that affects fluids, ask a doctor for your own target.
Frequently asked questions
- How much water should I drink a day?
- A common guide is about 30 to 45 ml of water per kilogram of body weight, depending on how active you are. For a 70 kg person who is moderately active that works out to roughly 2.8 litres, or about 12 cups, a day. Enter your weight above to get your own number.
- How does this water intake calculator work?
- It multiplies your body weight in kilograms by a millilitres-per-kilogram value set by your activity level. Sedentary uses 30 ml/kg, lightly active 35, moderately active 40, and very active 45. It then converts the total into litres and 240 ml cups.
- Does the 8 glasses a day rule still hold?
- Eight glasses is a rough rule of thumb, not a hard target. Your real need scales with your body size, activity, climate and diet. A small, lightly active person may do well on less, while a large athlete may need much more. This calculator gives a number tied to your own weight.
- Does food and other drinks count toward water?
- Yes. Around 20 percent of daily fluid comes from food, and tea, coffee, milk and juice all count toward the total. The figure here is total daily fluid, so you do not have to drink all of it as plain water. Spread your intake across the day.
- Can you drink too much water?
- Yes, though it is rare. Drinking very large amounts in a short time can dilute the sodium in your blood, which is dangerous. Drink to thirst and spread fluids out. If you have a heart, kidney or other medical condition that affects fluids, ask a doctor for your own target. This tool is general information, not medical advice.