How much water should I drink a day?

A common baseline is half your body weight in ounces. A 170 lb person would aim for ~85 oz (about 10 cups). Active individuals and those in hot climates need more.

Does coffee count toward water intake?

Yes, moderate coffee and tea intake counts toward hydration. While caffeine has a mild diuretic effect, the fluid content more than compensates.

What are signs of dehydration?

Dark yellow urine, dry mouth, headache, fatigue, and dizziness are common signs. Aim for pale yellow urine as a hydration indicator.

Can you drink too much water?

Yes, though rare. Excessive water intake can cause hyponatremia (low sodium). This typically only occurs with extreme consumption (several liters in a short time).

Water Intake Calculator

Calculate how much water you should drink daily based on weight, activity level, and climate.

Weight

lbs

Activity Level

Climate

Daily Water Intake

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In Liters —

In Cups —

Water Bottles (16.9oz) —

Extended More scenarios, charts & detailed breakdown ▾

Weight

lbs

Activity Level

Climate

Daily Intake

—

In Liters —

In Cups —

Water Bottles (16.9oz) —

Professional Full parameters & maximum detail ▾

Weight

lbs

Age

years

Gender

Activity Level

Climate

Pregnant / Breastfeeding

Altitude

Daily Target

Daily Water Target —

In Liters —

In Cups —

Bottle Equivalents

500ml Bottles —

16.9oz Bottles —

Source Breakdown

From Food (~20%) —

From Beverages Needed —

IOM Recommendation —

How to Use This Calculator

Enter your weight, activity level, and climate. The calculator shows your recommended daily water intake in ounces, liters, cups, and standard water bottles.

Formula

Base intake = Body weight (lbs) × 0.5 oz
Activity multiplier: Low 1.0 | Moderate 1.2 | High 1.5
Climate multiplier: Cold 0.9 | Temperate 1.0 | Hot 1.15

Example

Example: 170 lbs, moderately active, temperate climate: 170 × 0.5 × 1.2 × 1.0 = 102 oz (3.0 L, ~13 cups, ~6 water bottles).

Frequently Asked Questions

A common baseline is half your body weight in ounces. A 170 lb person would aim for ~85 oz (about 10 cups). Active individuals and those in hot climates need more.
Yes, moderate coffee and tea intake counts toward hydration. While caffeine has a mild diuretic effect, the fluid content more than compensates.
Dark yellow urine, dry mouth, headache, fatigue, and dizziness are common signs. Aim for pale yellow urine as a hydration indicator.
Yes, though rare. Excessive water intake can cause hyponatremia (low sodium). This typically only occurs with extreme consumption (several liters in a short time).

Related Calculators

Sources & References (5) ▾

Institute of Medicine (NASEM) — Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate (2005) — National Academies Press
Sawka MN et al. — American College of Sports Medicine Position Stand: Exercise and Fluid Replacement. Med Sci Sports Exerc. 2007;39(2):377-390 — ACSM / Medicine & Science in Sports & Exercise
Popkin BM et al. — Water, hydration, and health. Nutr Rev. 2010;68(8):439-458 — Nutrition Reviews
WHO — Nutrients in Drinking Water (2005) — World Health Organization
Mayo Clinic — Water: How much should you drink every day? — Mayo Clinic