Water Intake Calculator

Estimate a daily water intake target from your body weight and activity level — a starting point, not a medical prescription.

How this works: Uses the common baseline of about 35 ml per kg of body weight, then adds extra for exercise and hot/humid climates. Individual needs vary with health conditions, medications, pregnancy, and climate — check with a doctor for a target tailored to you, especially if you have kidney, heart, or other conditions affecting fluid balance.

Body weight

Exercise today (minutes)

Climate

2450 ml

Daily target (ml)

~10 cups

Roughly in cups / oz

Working out a number is one thing — actually drinking on schedule is another. A browser tab can't nudge you once you've moved on, but the MultiSwitch app's Repeat Reminder tool can ping you every 15, 20, or 30 minutes, even in the background.

A general estimate, not medical advice. Fluid needs vary with health conditions, pregnancy, breastfeeding, and medications — talk to a doctor about a target suited to you. See Terms.

Acronyms on this page:
EFSA — European Food Safety Authority: the EU body behind one of the fluid-intake guidelines referenced here.

FAQ

Where does the 35 ml/kg baseline come from?

It's a commonly cited general guideline (roughly in line with EFSA and other public health bodies' adequate-intake ranges) for a healthy adult at rest in a temperate climate. It's a starting estimate, not a clinical prescription.

Does this count fluid from food and other drinks?

No — this estimates total water intake target, which in practice comes from a mix of plain water, other drinks, and food (many fruits and vegetables are over 90% water). You don't need to hit the full number from water alone.

Should I drink more if I'm sick, pregnant, or on medication?

Possibly, but that's a question for a doctor, not a generic calculator — fever, vomiting, pregnancy, breastfeeding, and various medications and health conditions can all shift fluid needs up or down significantly.

FAQ

Related tools