Hydration basics

How Much Water Should I Drink?

A practical starting point is 30 to 35 ml per kilogram of body weight per day. Your real target changes with heat, activity, sleep and sweating.

Note: This guide is for general information only and does not replace medical advice. If you have kidney, heart or metabolic conditions, ask a clinician before changing fluid intake.

The most useful way to think about water intake is not a fixed number like "2 liters". It is a range. A 55 kg person and a 95 kg person do not have the same needs, and a hot day changes the target again.

The simple formula

Low estimate30 ml x body weight
Practical target35 ml x body weight
Heat adjustmentMore water when it is hot
Activity adjustmentMore water when you sweat

Example: a 70 kg adult starts at roughly 2.1 to 2.45 liters per day. On a warm day, with a walk, workout or poor sleep, the needed amount is higher.

What changes your daily target?

The best habit is simple: drink regularly during the day instead of waiting for thirst. Thirst is late. By the time you feel it, you are already behind.

Track the right amount with Brim

Brim helps you log intake fast, see progress clearly and keep hydration on track without manual spreadsheets.

Free on the App Store
Related Brim guides: Water intake calculator · Hydration reminder · Dehydration symptoms · Water tracker app

FAQ

How much water should I drink daily?

Use 30 to 35 ml per kilogram as a starting point, then adjust for heat, sport and sweating.

Is one fixed number enough for everyone?

No. It is a rough average only. Personal needs move with temperature, activity and body size.

What is the easiest way to stay consistent?

A reminder plus a tracker usually works better than trying to remember everything manually.

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