Our Mission

WaterIntakeCalc.com was created to provide a simple, accurate, and completely free way for anyone to calculate their daily water needs. We believe hydration guidance should be accessible to everyone - no signup walls, no subscriptions, no hidden fees.

Scientific Basis

Our calculator is based on the following authoritative sources:

Institute of Medicine (IOM) 2005 - Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate. The primary scientific authority on water requirements. (NAP.edu/10925)
Harvard T.H. Chan School of Public Health - The Nutrition Source: Water. Translates IOM Adequate Intakes into practical cup measurements. (Harvard Nutrition Source)
Mayo Clinic - Water: How much should you drink every day? Clinical guidance on hydration for various conditions. (Mayo Clinic)
Holliday & Segar (1957) - Pediatric maintenance fluid requirements (weight-based formula for children).
Adolph (1933) - Physiological Regulations. The 1 mL per kcal expended formula.

What Makes Us Different

No Signup Required

Use the calculator instantly. No account, no email, no tracking.

Science-Based

Every formula cites its source. No made-up numbers.

Gender-Specific

Separate base formulas for men (35mL/kg) and women (30mL/kg) per IOM.

Comprehensive

Accounts for weight, activity, climate, pregnancy, breastfeeding, and age.

Shareable Results

Generate a link with your inputs pre-filled to share with family or patients.

Privacy-First

All calculations run in your browser. No data sent to our servers.

Medical Disclaimer

This website provides general hydration guidance based on population-level recommendations. It is not a substitute for professional medical advice, diagnosis, or treatment. Individual hydration needs vary based on health conditions, medications, climate, and activity. Always consult a qualified healthcare provider for personalized medical advice, especially if you have kidney disease, heart failure, diabetes, or are taking medications that affect fluid balance.

Contact

Questions, suggestions, or found an error? We'd love to hear from you.