Water Intake Calculator
Calculate how much water you should drink daily based on your weight, activity level, and climate. Free, instant, no sign-up.
General wellness estimate, not medical advice. If you have a kidney, heart, or other condition affecting fluid balance, or are pregnant or breastfeeding, check with a doctor about your specific needs.
Your Details
Today's Tracker
0 / 13
glasses today
Saved automatically — resets each day.
Your recommended daily water intake
3.2
liters
3,160
ml
107
fl oz
13
glasses (8oz)
How This Was Calculated
Daily Water Intake Chart by Weight
Assumes a temperate climate. Generated from the same formula as the calculator above.
| Weight | Sedentary | Moderate | Intense |
|---|---|---|---|
| 45kg / 99lb | 1.6L | 2.3L | 2.8L |
| 55kg / 121lb | 1.9L | 2.6L | 3.1L |
| 65kg / 143lb | 2.3L | 3L | 3.5L |
| 75kg / 165lb | 2.6L | 3.3L | 3.8L |
| 85kg / 187lb | 3L | 3.7L | 4.2L |
| 95kg / 209lb | 3.3L | 4L | 4.5L |
| 105kg / 231lb | 3.7L | 4.4L | 4.9L |
| 115kg / 254lb | 4L | 4.7L | 5.2L |
Support Our Free Tools
If you find this calculator helpful, please consider supporting our work. Your contribution helps us build and maintain these free tools for everyone.
Buy me a coffeeHow Much Water Should You Drink a Day?
"Drink eight glasses of water a day" is easy to remember, but it isn't personalized — a larger, more active person in a hot climate needs a lot more fluid than someone smaller and sedentary in a mild one. General guidelines from the National Academies of Sciences put total fluid intake (including food) at roughly 3.7 liters a day for men and 2.7 liters for women, but your own number depends on your weight, how active you are, and the climate you're in. This calculator combines all three to give you a personalized daily water intake target, shown in liters, ounces, and glasses.
How the Calculation Works
The formula behind this calculator is transparent by design — you can see the exact breakdown next to your result. It starts with a base amount tied to your body weight, then adds more for activity and heat, since both increase how much fluid you lose through sweat.
⚖️ Base: body weight
About 35ml of water per kilogram of body weight — a heavier body simply needs more fluid to function.
🏃 Add: activity level
Exercise increases fluid loss through sweat, so the more active you are, the more this calculator adds on top of your base amount.
🌡️ Add: climate
Heat, humidity, and high altitude all increase fluid loss, so hotter climate settings add extra water to your daily target.
Water Intake and Weight Loss
Water itself has no calories and doesn't directly burn fat, but staying properly hydrated supports a healthy metabolism and can help you tell the difference between hunger and thirst. Replacing sugary drinks with water is also one of the easiest ways to cut empty calories from your day. Use this calculator to find a solid daily water target, and treat it as one healthy habit among many — not a stand-alone weight-loss plan.
Frequently Asked Questions
How much water should I drink a day?
General guidelines suggest around 3.7 liters of total fluids a day for men and 2.7 liters for women, including food. Your ideal amount depends on your weight, activity level, and climate — this calculator personalizes that estimate for you.
How is my daily water intake calculated?
The calculator starts with a base of about 35ml per kilogram of body weight, then adds extra fluid for your activity level and climate. The full breakdown is shown alongside your result.
How much water should I drink based on my weight?
Heavier bodies generally need more water. As a starting point, multiply your weight in kilograms by about 35ml — the chart above shows typical targets across a range of weights and activity levels.
Does drinking more water help with weight loss?
Water itself doesn't burn fat, but staying well hydrated can support your metabolism and help you feel fuller, and swapping sugary drinks for water cuts empty calories. It's a helpful habit alongside a balanced diet, not a weight-loss method on its own.
Does exercise increase how much water I need?
Yes. You lose extra fluid through sweat during exercise, so this calculator adds more water to your target the more active you say you are.
Does hot weather change my water needs?
Yes. Heat and humidity increase fluid loss through sweat, and high altitude can increase fluid needs too, so the calculator adds extra water for hot or very hot climate settings.
Is this a medical recommendation?
No. This is a general wellness estimate, not medical advice. If you have a kidney, heart, or other condition that affects fluid balance, or you are pregnant or breastfeeding, talk to a doctor about your specific fluid needs.
Explore More Health & Fitness Calculators
The Water Intake Calculator is part of Texterfly's growing collection of free, evidence-based health calculators — no sign-up, nothing sent to a server.
Explore All Tools
134 free tools — no signup required
All 134 tools are free · No signup · No ads