Note: This is a practical estimate, not medical advice. People with heart, kidney or metabolic conditions should ask a clinician before changing fluid intake.
The body-weight formula
A useful baseline is 30 to 35 ml per kilogram of body weight. This gives you a range instead of pretending one fixed number works for everyone.
| Body weight | Lower estimate | Upper estimate |
|---|---|---|
| 55 kg | 1.65 L | 1.93 L |
| 70 kg | 2.10 L | 2.45 L |
| 85 kg | 2.55 L | 2.98 L |
| 100 kg | 3.00 L | 3.50 L |
When to add more
- Hot weather or humid rooms
- Workouts, long walks or outdoor work
- Fever, heavy sweating or poor sleep
- Alcohol or a salty meal
Weight gives you the baseline. Your day decides the final number. That is why a living target is more useful than a static note in your phone.
Brim starts with your personal target
Track intake, keep your progress visible and adjust your routine when your day gets hotter or more active.
Free on the App StoreRelated Brim pages: Water intake calculator · How much water should I drink? · Apple Health tracking · Water tracker widget
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