Daily hydration calculator
HealthEstimate your daily water intake needs using body weight and activity level.
Moderately active
Exercise 3 to 5 days per week.
Jogging
Gym
Cycling
Recreational sports
Advanced options
Your results
Plan your daily hydration based on weight and activity level.
How hydration is estimated
This calculator estimates your daily water intake from your body weight and activity level. If you provide additional details such as age, sex, and height, it also uses the Mifflin-St Jeor equation to personalize the recommendation based on your basal metabolic rate. Results are a general reference and may vary with climate, health status, and other factors.
Hydration reminders
Hydration needs vary from person to person. Climate, physical activity, sweating, sodium intake, pregnancy, breastfeeding, and certain health conditions can all affect how much water you may need. Use this estimate as a starting point and adjust your intake to your individual needs and to the guidance of a health professional when appropriate.
Frequently asked questions
Answers to the most common questions about this tool.
How is this result calculated?
It uses the method and inputs described on this page to provide an informational estimate.
How accurate is the result?
It is an estimate and should be interpreted as a guide, not an exact measurement.
When should I seek professional advice?
Seek qualified advice for symptoms, pregnancy, illness, medication use, or clinical decisions.
What information do I need to enter?
Enter current, accurate details and select the correct units before calculating.
What can affect this estimate?
Individual factors such as health, activity, body composition, and measurement technique can affect it.
Sources and methodology
Methodology: Hydration estimate
Uses 33 ml/kg plus an activity bonus. With an advanced profile, it uses BMR × 0.001 plus the same bonus; both are ToolsRL approximations.
The external reference describes general water needs, not these exact formulas.
Last reviewed
July 15, 2026