Water Intake Calculator

--Millilitres/day
--Litres/day
--Glasses/day (250 ml)

Suggested Drinking Schedule

TimeAmount

How Much Water Should You Drink Per Day?

The amount of water your body needs daily depends on several factors including your body weight, physical activity level, climate, and overall health. Common recommendations suggest drinking 35 ml of water per kilogram of body weight as a baseline, with increases for exercise and hot environments. For a 70 kg person, this works out to about 2.5 litres per day under normal conditions.

Why Hydration Is Vital

Water makes up approximately 60% of the human body and is involved in every major physiological process: regulating body temperature, transporting nutrients, flushing waste products, lubricating joints, and supporting cognitive function. Even mild dehydration of 1–2% of body weight can impair physical performance, concentration, and mood.

Signs of Dehydration

  • Dark yellow or amber-coloured urine (pale yellow is ideal)
  • Dry mouth and increased thirst
  • Headache, fatigue, or dizziness
  • Reduced urine output
  • Difficulty concentrating

Tips for Drinking More Water

Keep a water bottle at your desk or in your bag. Set hourly phone reminders. Drink a glass of water first thing in the morning and before each meal. Herbal teas, fruits, and vegetables also contribute to daily fluid intake. Caffeinated drinks like coffee have a mild diuretic effect but still count towards hydration at moderate consumption levels.

Frequently Asked Questions

Is 8 glasses of water per day a myth?
The "8 glasses" rule is a simplified guideline, not based on rigorous science. Actual needs vary significantly by body size, activity, and climate. Using your weight as the basis for calculation, as this tool does, is more personalised and accurate.
Does coffee and tea count toward my water intake?
Yes. Despite being mild diuretics, caffeinated beverages like coffee and tea still provide net hydration. Research shows that moderate coffee consumption (up to 4 cups/day) contributes positively to fluid balance.
Can you drink too much water?
Yes. Overhydration (hyponatraemia) can occur, especially in endurance athletes who drink excessive plain water. It dilutes sodium levels in the blood. However, this is rare in normal daily life.
How does exercise increase water needs?
During exercise you lose water through sweat and respiration. Even in moderate conditions, a 1-hour workout can require an additional 500–750 ml of water. In hot weather or during intense exercise, losses can exceed 1 litre per hour.