How much water should I drink per day?

A common reference is approximately 30-35mL per kg of body weight, adjusted for activity level and environment. For a 70kg person, this comes to about 2100-2450mL as a baseline.

Does coffee and tea count toward water intake?

Yes. While caffeine has a mild diuretic effect, the net hydration from moderate coffee and tea consumption remains positive. Most of the water content is retained by the body.

🥤 Water Intake Calculator

Estimate daily water intake based on body weight

Weight (kg)

Exercise Level

Weather

Estimated daily water intake

2.3 L

2340 mL / 9 cups (250mL each)

Milliliters

2340 mL

Standard Cups

9 cups

Water Intake Calculator Guide

This calculator estimates your recommended daily water intake based on body weight, exercise level, and environmental factors. General guidelines suggest 1,500-2,500 ml per day for adults.

Water is the most essential nutrient, making up about 60% of body weight. Even mild dehydration (2% body weight loss) can impair cognitive function and physical performance.

Scientific Hydration Guide

Daily water intake reference:

- Base requirement: Body weight (kg) × 30-35 ml - Exercise addition: 300-500 ml per 30 minutes of exercise - Hot weather: Add 500-1,000 ml

Hydration timing: - Morning: 1 glass of warm water (200-300 ml) - 30 minutes before meals: 1 glass - Before and after exercise: 200-300 ml each - 1 hour before bed: Small amount

Tip: Don't wait until you're thirsty — thirst indicates mild dehydration. Coffee and tea have diuretic effects and cannot fully replace plain water.

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Water Intake Calculator Guide

The human body is approximately 60-70% water. Water is involved in nearly all physiological processes: nutrient transport, temperature regulation, waste removal, joint lubrication, and digestion.

This calculator estimates daily water intake based on your body weight, activity level, and environmental conditions. The result is displayed in both liters and cups for convenience.

Note: This estimate refers to water intake from beverages. Food also contributes to total fluid intake (fruits and vegetables are 80-95% water).

Daily Water Intake Formula

Base formula:
Base water intake = weight(kg) × 30 mL/kg

Activity adjustment:
Low activity: ×1.0
Moderate activity: ×1.2
High activity: ×1.5

Environment adjustment:
Hot weather: ×1.15

Example (70kg, moderate activity, normal weather):
= 70 × 30 × 1.2 = 2520 mL ≈ 2.5 L

Understanding Hydration

Water balance involves intake and output:

Water sources: • Beverages: 1200-1500 mL (primary source) • Food: 700-1000 mL • Metabolic water: ~300 mL

Water output: • Urine: 1000-2000 mL/day • Skin evaporation: 400-800 mL/day • Respiration: 300-400 mL/day • Feces: 100-200 mL/day • Sweat during exercise: 0-2000+ mL/day

Dehydration indicators: • Mild (1-2% body weight loss): thirst, dry mouth, dark urine • Moderate (3-5%): headache, decreased skin elasticity, increased heart rate • Severe (6%+): dizziness, confusion, low blood pressure

Urine color is a simple hydration indicator: pale yellow = well hydrated; dark yellow = need more fluids.

Water Intake Examples

📋

Example 1: Sedentary office worker (72kg) Base: 72 × 30 × 1.0 = 2160 mL/day ≈ 2.2 L Example 2: Active individual (55kg, high activity) Base: 55 × 30 × 1.5 = 2475 mL/day ≈ 2.5 L Example 3: Hot weather outdoor worker (80kg, high activity) Base: 80 × 30 × 1.5 × 1.15 = 4140 mL/day ≈ 4.1 L

Notes

💡

• Avoid drinking more than 1L per hour to prevent hyponatremia • Exercise lasting over 1 hour may benefit from electrolyte-containing beverages • Individuals with kidney or heart conditions should follow medical guidance on fluid intake • Thirst is already a sign of mild dehydration Common misconceptions: • "8 glasses a day" is a rough guideline, not a universal rule • Coffee and tea do contribute to hydration (net positive effect) • Water intake needs vary significantly between individuals

Common Use Cases

- Estimating daily water intake needs
- Adjusting hydration for exercise and hot weather
- Understanding factors that affect water requirements
- General hydration awareness

Hydration Reference by Population

General reference values for different groups:

| Group | Daily Reference Intake | |-------|----------------------| | Adult male | 2500-3000 mL | | Adult female | 2000-2500 mL | | Pregnant women | +300 mL | | Breastfeeding women | +700 mL | | Children (4-8) | 1200-1600 mL | | Adolescents | 2100-2800 mL | | Elderly (65+) | 1500-2000 mL | | Hot environment workers | +500-1000 mL |

These are general reference values. Individual needs vary based on body size, activity, climate, and health conditions.

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