How to use this calculator
- 1
Enter your body weight
Imperial or metric — the calculator handles conversions.
- 2
Add activity and climate
Activity level, hours of training, and ambient climate (cool, hot/humid).
- 3
Add special factors
Pregnancy, lactation, illness, and high-altitude all increase water needs.
- 4
Read your daily target
Total daily water in ounces, liters, and cups, plus a recommended hourly schedule.
What this calculator gives you
- Body-weight-based baseline (0.5–1 oz per pound)
- Climate and altitude adjustments
- Pre-/intra-/post-workout hydration plan
- Pregnancy and lactation adjustments
- Electrolyte guidance for high-volume days
Formulas used
Baseline (adult)
~30–35 mL/kg (0.5–0.6 oz/lb)
Best for: Sedentary, temperate climate baseline
Active adults
Baseline + 12–16 oz per hour of training
Best for: Replacing sweat losses during exercise
Hot or humid climate
Baseline + 16–32 oz/day
Best for: Compensating for higher sweat rate
Frequently asked questions
How much water should I drink per day?+
Baseline is about 0.5–1 oz per pound of body weight (30–35 mL/kg). The Institute of Medicine references 2.7 L/day for women and 3.7 L/day for men including water from food.
Does coffee count toward water intake?+
Yes. The diuretic effect of caffeine is mild and well below the volume of water in the drink. Coffee, tea, and other beverages count toward total water intake.
How do I know if I am drinking enough water?+
Pale-yellow urine and infrequent thirst are reliable indicators. Dark-yellow urine, frequent thirst, headaches, or low energy can signal mild dehydration.
Can I drink too much water?+
Yes — hyponatremia (low sodium) is rare but real, usually in endurance athletes who drink large volumes without electrolytes. For most people, drinking to thirst plus the calculated baseline is safe.
Want the full guide?
The complete article goes deeper into the science, with charts, comparisons, and practical examples.
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