Proper hydration is essential for health. Calculate your recommended daily water intake based on your body weight to stay energized and support bodily functions.
Proper hydration is crucial for overall health. Water regulates body temperature, lubricates joints, aids in digestion and nutrient absorption, and improves brain function. Calculating your daily water intake helps ensure your body has the resources it needs to perform at its best.
While individual needs vary, a common recommendation is based on body weight:
Daily Water Intake (ml) = 30–35 ml × Your Body Weight in kg
Example: A 70 kg person would need approximately 70 × 35 = 2450 ml (or 2.45 liters) of water per day.
Note: You should adjust your intake based on factors like exercise, climate, and pregnancy. This calculator provides a baseline recommendation.
Reference: National Academies of Sciences, Engineering, and Medicine (IOM).
The calculator above uses the most practical rule of thumb: about half your body weight in pounds, in fluid ounces (roughly 30–35 mL per kilogram). A 180 lb (82 kg) person lands near 90 oz (2.7 L) a day. For a second reference point, the U.S. National Academies set adequate total water intake at about 3.7 liters a day for men and 2.7 liters for women — that includes water from food, which supplies roughly 20% of the total.
| Body Weight | Daily Water Target |
|---|---|
| 120 lb (54 kg) | 60 oz (1.8 L) |
| 150 lb (68 kg) | 75 oz (2.2 L) |
| 180 lb (82 kg) | 90 oz (2.7 L) |
| 200 lb (91 kg) | 100 oz (3.0 L) |
| 220 lb (100 kg) | 110 oz (3.3 L) |
Treat the number as a baseline, then adjust it. Add roughly 12 oz for every 30 minutes of exercise, more on hot or humid days, and more when you are ill, feverish, or sweating heavily. People who are pregnant need extra fluids (about 10 cups a day), and breastfeeding parents need still more (about 13 cups). Thirst is a late signal — pale-yellow urine through the day is a better gauge.
Two myths worth retiring: the rigid "8 glasses" rule was never evidence-based — needs vary widely by size, diet, and climate — and coffee and tea do count toward hydration. Caffeine is a mild diuretic, but the fluid in your cup more than makes up for it. On the other extreme, drinking far beyond thirst during endurance events can dilute blood sodium (hyponatremia), so extreme athletes should plan intake rather than force fluids. For a plain-language overview of why water matters, the CDC's page on water and healthier drinks is a solid starting point.
Maintained by Live Fitness Check. Last updated: August 9, 2026. How we test our calculators .
Estimates a daily water-intake target from body weight.
The calculator applies the weight-based hydration factor configured in the live tool and converts the result into an easy daily target. The calculation uses body weight.
Fluid requirements vary with climate, activity, diet, pregnancy, illness, medications and heart or kidney conditions. Use the number as an estimate and consider professional advice when the result may affect health, treatment, pregnancy, nutrition, exercise safety or another important decision.
