FinanceHealthMathDev ToolsDate & TimeText ToolsConvertersUtilitiesBusinessConstructionAgricultureAutomotiveScienceStatisticsEducationLegal & TaxAbout

Water Intake Calculator

Find out exactly how much water you should drink each day. Based on your weight, activity level, and climate — with targets in litres, ml, and glasses.

Your Details
Unit System
Body Weight70 kg
kg
20200
Activity Level
Climate
Your Result

Fill in the details and
your result appears here.

Daily Water Intake
Daily Water (Litres)
Daily Water (ml)
Standard Glasses (250ml)
Large Bottles (1L)
Hourly Target (16 hrs awake)
Related Calculators

Did You Know?
Drink before you feel thirsty
Thirst signals that you're already 1–2% dehydrated. At 2% dehydration, athletic performance drops by up to 10% and cognitive function declines. Sip steadily through the day rather than gulping large amounts at once.

How to use this calculator

1

Enter your weight

Water needs scale with body weight — heavier bodies need more water to function.

2

Select activity level

Exercise increases water loss through sweat significantly.

3

Select your climate

Hot and humid climates like India increase baseline water needs substantially.

The formula explained

Base Water = Weight(kg) × 35 ml
Adjusted = Base × Activity Multiplier + Climate Addition

The base formula (35ml per kg) is a widely used clinical guideline. Activity increases sweat loss significantly — a 1-hour run can require an additional 500–1000ml. Hot climates add 200–400ml baseline need.

Frequently Asked Questions

Is the 8 glasses a day rule accurate?

The "8 glasses" rule is a rough approximation. Actual needs vary significantly by weight, activity, and climate. A 50kg sedentary person needs less than a 90kg athlete in a hot climate.

Does tea and coffee count towards water intake?

Yes — despite mild diuretic effects, caffeinated drinks like tea and coffee still contribute net fluid. However, water remains the best source. Avoid counting sugary drinks.

What are signs of dehydration?

Dark yellow urine, dry mouth, fatigue, headache, and reduced concentration. Pale yellow urine indicates good hydration. Clear urine may indicate over-hydration.

Can you drink too much water?

Yes — hyponatremia (water intoxication) occurs when sodium is diluted by excessive water intake. This is rare in normal conditions but can happen during extreme endurance events.

How do I know if I am drinking enough water?

Signs of adequate hydration: pale yellow urine, no thirst, good skin elasticity. Signs of dehydration: dark yellow urine, headache, fatigue, dizziness. Thirst is a late signal — drink proactively throughout the day.

More Health Calculators