Daily Water Intake: How Much Water Do You Really Need?

The "8 glasses a day" rule is a myth. Your actual water needs depend on many factors.

How to Calculate Your Water Needs

Basic Formula

Body weight (kg) × 30–35 mL = daily water intake in mL

Example: 70 kg × 33 mL = 2,310 mL (~2.3 liters)

Adjustments

Add more water for:

• Exercise: +500–1000 mL per hour of exercise
• Hot/humid weather: +500–750 mL
• High altitude: +500 mL
• Pregnancy: +300 mL
• Breastfeeding: +700 mL
• Illness (fever/diarrhea): +500–1000 mL

Signs of Dehydration

Mild

• Thirst
• Slightly dark urine
• Dry mouth
• Mild headache

Moderate

• Very dark urine
• Decreased urination
• Dizziness
• Fatigue

Severe (seek medical attention)

• No urination
• Rapid heartbeat
• Confusion

The Urine Color Test

The simplest hydration check:

• Pale yellow: Well hydrated
• Dark yellow: Need more water
• Clear: Possibly over-hydrated

Water Intake Tips

1. Start your day with water: Drink 500 mL upon waking

2. Carry a bottle: Visual reminder to drink

3. Set reminders: Use phone alarms every 1–2 hours

4. Eat water-rich foods: Cucumber (96%), watermelon (92%), oranges (87%)

5. Drink before meals: Helps with portion control too

Do Other Beverages Count?

• Tea/coffee: Yes, despite mild diuretic effect, the net hydration is positive
• Juice/milk: Yes, but watch for added sugars/calories
• Soda: Technically hydrates but not recommended
• Alcohol: Net dehydrating — does NOT count

Use our unit converter to convert between water measurement units.