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Find your ideal daily water intake.
💧 General guideline: ~35 ml per kg body weight, more with exercise or heat. Individual needs vary.
This calculator estimates how much water you should drink daily, based on body weight, exercise, and climate. It uses the widely cited guideline of ~35 ml per kg of body weight, adjusted for activity and heat.
Formulas are starting points, not rules. Thirst is a reliable signal for most people. Check urine color — pale yellow means you're well hydrated; dark yellow means drink more. Clear urine means you may be overhydrated.
Yes. Hyponatremia(low blood sodium from excessive water) is rare but dangerous, and has affected endurance athletes who drink far more than they lose. Don't force multiple liters beyond thirst unless advised by a doctor.
Disclaimer: This tool is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Results are estimates and should be discussed with a qualified healthcare provider before making health-related decisions.
The Water Intake Calculator lets you figure out water intake calculatorinstantly, without reaching for a spreadsheet or doing the math by hand. Whether you're planning a budget, checking a loan, or working through homework, the tool applies the correct formula behind the scenes and shows the result the moment you enter your numbers.
Unlike a static chart or table, this calculator adapts to your exact inputs. You can adjust any value and see the outcome update in real time, which makes it easy to compare scenarios — for example, "what if the rate were 1% lower?" or "what if I paid an extra $50 a month?"
Common uses: people reach for this tool when they need to find a water intake calculator by weight, how much water should i drink, daily water intake by activity, or hydration calculator by body weight.
Browser-based tools like this one have a few real advantages over installed software or manual methods:
The Water Intake Calculator is based on the following formula:
Water (ml) ≈ 35 ml × weight (kg) [ ≈ 0.5 oz × weight (lb) ]
Variables: Water (ml) = Daily water intake target (milliliters) weight (kg) = Body weight (kilograms) weight (lb) = Body weight (pounds) oz = Fluid ounces per day (1 oz ≈ 30 ml) 35 = Baseline milliliters of water per kg of body weight
A common hydration baseline: about half your body weight in pounds, taken as ounces per day — roughly 35 ml per kg. The calculator then adjusts this baseline upward for exercise, hot climate, and pregnancy.
Worked example: Step 1: Body weight 68 kg (about 150 lb). Step 2: 35 × 68 = 2,380 ml. Step 3: Cross-check in imperial: 0.5 × 150 = 75 oz ≈ 2,219 ml, the same ballpark. Result: about 2,380 ml (roughly 2.4 liters) of water per day before adjustments for exercise, heat, or pregnancy.
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