Water Intake Calculator
Find out exactly how much water you should drink every day
Why does hydration matter? Water makes up approximately 60% of the human body and is involved in virtually every bodily function — from regulating temperature and transporting nutrients to lubricating joints and flushing out waste. Even mild dehydration of just 1 to 2% of body weight can impair physical performance, reduce cognitive function, and increase fatigue. Most people underestimate how much water they actually need.
Calculate Your Daily Water Intake
Signs You Are Not Drinking Enough Water
⚠️ Mild Dehydration (1-2%)
- Thirst and dry mouth
- Darker urine than usual
- Reduced concentration
- Slight headache
- Reduced exercise performance
🚨 Moderate Dehydration (3-5%)
- Significant thirst
- Dark yellow urine
- Fatigue and low energy
- Dizziness
- Muscle cramps
🆘 Severe Dehydration (6%+)
- Very dark or no urine
- Rapid heartbeat
- Confusion
- Sunken eyes
- Seek medical attention immediately
Real Example — Maya’s Hydration Plan
Maya is 38 years old, weighs 80kg, lives in a warm climate and does 30 minutes of brisk walking daily. Her daily water target is approximately 2.8 litres per day.
Maya’s hydration schedule:
- 7am — Wake up: 500ml immediately upon waking (rehydrates after 7-8 hours without water)
- 9am — Mid-morning: 300ml with breakfast
- 11am — Before walk: 300ml before exercise
- 12pm — During/after walk: 400ml during and after 30 min walk
- 1pm — Lunch: 300ml with meal
- 3pm — Afternoon: 300ml
- 6pm — Dinner: 300ml with meal
- 8pm — Evening: 400ml before bed
Maya noticed that when she consistently hit her water target her appetite reduced, her skin improved, and her energy during walks was significantly better — all within just 2 weeks of consistent hydration.
10 Practical Tips to Drink More Water
- Start every morning with 500ml of water immediately after waking
- Drink a glass of water before every meal — reduces appetite too
- Carry a large water bottle (1L+) everywhere you go
- Set hourly reminders on your phone to drink water
- Add lemon, cucumber, or mint for flavour if plain water feels boring
- Drink 400-600ml before and during any exercise session
- Eat high water content foods — cucumber, watermelon, oranges, lettuce
- Replace one coffee or sugary drink per day with water
- Check your urine colour — aim for pale yellow throughout the day
- Increase intake by 500ml per 30 minutes of exercise in hot weather
Research reference: The National Academies of Sciences recommends a total daily water intake of 3.7 litres for men and 2.7 litres for women from all sources including food (which provides approximately 20% of total intake). These values increase significantly with exercise, heat exposure, and certain health conditions.
Source: Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate. National Academies of Sciences. 2005. Cited in multiple NIH publications.
Also Calculate Your Daily Calorie Needs
Use our free TDEE Calculator alongside your water intake for a complete health plan.
All Free Calculators →Disclaimer: Water intake recommendations are estimates based on body weight and activity level. Individual needs vary significantly. People with kidney disease, heart failure, or other medical conditions should consult their doctor before significantly increasing water intake.
