How much water should I drink each day?

A practical starting point is 35 mL per kilogram of body weight, plus about 12 mL per minute of exercise. The calculator personalizes this with climate and life-stage adjustments.

Do all drinks count toward hydration?

Yes. All fluids contribute, and water-rich foods provide roughly 20–30% of total water intake.

When should I drink more water?

In hot or humid weather, at altitude, or during longer exercise sessions. Sip regularly and use thirst and pale urine color as checks.

Water Intake: Your Personalized Daily Target

Quick Profile

Pick what fits best—this adjusts activity/climate defaults (you can still edit on the right).

Hydration Setup

Calculate my daily target

Weight

Exercise / day

Climate

Life stage Goal

Pouring water into a glass on a bright table

Key Takeaways

Daily water needs vary with body size, activity, climate, diet, and life stage.
A practical starting point is 35 mL per kg body weight, plus about 12 mL per exercise minute.
Hot or humid weather and high altitude increase needs; sip regularly rather than chug at once.
All fluids count toward hydration, and water-rich foods contribute ~20–30% of intake.
Use thirst and urine color (pale straw) as quick hydration checks.

Hydration supports temperature regulation, cardiovascular function, digestion, cognition, and physical performance. Use the calculator above to tailor a daily target to your weight, activity, climate, and life stage, then spread your intake through the day.

How much water do I need?

There isn’t a single number for everyone. The table below lists broad daily totals (fluids + the water that’s naturally in foods). Your personal target may be higher on hot days or during exercise.

General daily water targets (total water from drinks + foods)
Group	Age	Approx. total per day	Typical from drinks*
Infant (w/ foods)	4–12 months	~0.8–1.0 L	~0.6–0.8 L
Toddlers	1–2 yrs	~1.3 L	~1.0 L
Preschool	3–5 yrs	~1.7 L	~1.3 L
School-age	6–12 yrs	~1.9–2.4 L	~1.4–1.9 L
Teens	13–18 yrs	~2.3–3.3 L	~1.8–2.6 L
Adults	18+ yrs	2.7 L (women), 3.7 L (men)	~2.0 L (women), ~2.7 L (men)
Pregnancy	—	~3.0 L	~2.2 L
Breastfeeding	—	~3.8 L	~2.9 L

*Many people get ~70–80% of total water from drinks and ~20–30% from foods. Values are broad educational ranges (not medical advice).

Simple timing tips

After waking: a glass of water to start the day.
Before meals: 1 glass ~30 minutes before eating.
During exercise: ~150–250 mL every 15–20 minutes as a starting point; adjust for heat and sweat rate.
After exercise: if you track weight, ~1.5 L per kg body mass lost; otherwise sip until urine is pale.

When to be cautious

Kidney, heart, or liver conditions; diuretics; or clinician-directed fluid limits.
Don’t overdo it: avoid repeatedly drinking >1 L per hour for long periods without electrolytes.

How this calculator works

We estimate a baseline of 35 mL per kg body weight, add 12 mL per minute of moderate–vigorous exercise, then apply climate (+20% for hot/humid) and life-stage adjustments (pregnancy +0.3 L, breastfeeding +0.7 L). Use the result as a starting point and adjust to thirst and conditions.

For personal medical guidance, speak with a qualified health professional.