Note: This calculator is for general adults, not for pregnancy dieting. If you are pregnant, please follow your doctor’s advice.

How Much Water Should You Drink Per Day?

Everyone has heard “drink eight glasses a day”, but your body is not a standard glass count. A 55 kg woman in a cool room and an 85 kg man who trains in 40°C heat need very different amounts. Our water intake calculator works out your daily target in litres, glasses and bottles from your weight, exercise, weather and life stage. It also builds a drinking schedule for your day and a special plan for Ramadan fasting days.

Quick Answer: How Much Water Should You Drink Per Day?

Group	Total water per day (drinks and food)	Drinks only (approx.)
Adult men	About 3.7 litres	About 3.0 litres
Adult women	About 2.7 litres	About 2.2 litres
Pregnant women	About 3.0 litres	About 2.4 litres
Breastfeeding women	About 3.8 litres	About 3.0 litres

These adequate-intake figures come from the US National Academies and include water from food, which supplies roughly 20% of the total. Your own number can be higher or lower, and that is exactly what the calculator is for.

What Is a Water Intake Calculator?

A water intake calculator estimates how much fluid you should drink each day. Most start with your body weight and then add extra for exercise, hot weather and special situations such as pregnancy. It gives you a practical target instead of a one-size-fits-all rule.

How Does This Calculator Work?

1. Base amount. 33 ml of fluid per kg of body weight. This is a common rule of thumb used by dietitians, and it lands close to official recommendations for most adults.
2. Exercise. We add fluid for every minute you exercise, based on how hard it is: about 6 ml per minute for light activity, 10 ml for moderate and 14 ml for hard exercise.
3. Weather. Add 500 ml for warm weather (25 to 35°C) and 1,000 ml for hot or humid weather above 35°C.
4. Pregnancy or breastfeeding. Add 300 ml or 700 ml, in line with European Food Safety Authority guidance. The US figures for breastfeeding are a little higher, so drink to thirst as well.
5. Rounding and food. The total is rounded to the nearest 50 ml. We also show the total water including about 20% from food.
6. Schedule. Your total is split into 8 drinks between waking up and 90 minutes before bed, or into a 7-part plan on Ramadan days.

Water Intake Formula With Example

A 70 kg man, jogging for 30 minutes a day, living in a warm climate.

Step	Calculation	Result
Base	33 ml × 70 kg	2,310 ml
Exercise	30 min × 10 ml	+ 300 ml
Weather (warm)		+ 500 ml
Daily target	Rounded	3,100 ml (about 12 glasses)
Total water including food	3,100 ÷ 0.8	About 3.9 litres

Water Needs by Body Weight

Drinks only, with a warm climate and 30 minutes of moderate exercise.

Body weight	Base (33 ml/kg)	Daily target
50 kg	1.65 L	2.45 L
60 kg	1.98 L	2.8 L
70 kg	2.31 L	3.1 L
80 kg	2.64 L	3.45 L
90 kg	2.97 L	3.75 L
100 kg	3.30 L	4.1 L

What Changes Your Water Needs?

Factor	What happens	What to do
Hot or humid weather	You sweat more	Add 0.5 to 1 litre
Exercise	Sweat can reach 0.5 to 2 litres an hour	Drink before, during and after
Pregnancy	Blood volume and amniotic fluid rise	Add about 300 ml
Breastfeeding	Milk is mostly water	Add about 700 ml
Fever, vomiting or diarrhoea	Fast fluid loss	Sip often and use ORS
High altitude	Faster breathing and urine loss	Drink more than usual
Older age	Thirst signal weakens	Sip by the clock
High protein or high fibre diet	More water needed to process	Increase gradually

Water Intake During Ramadan

On fasting days you cannot drink between dawn and sunset, so your whole daily amount has to fit into the night. Spreading it out works much better than gulping everything at iftar.

When	Share of your daily water
At iftar, when you break your fast	15%
30 minutes after eating	15%
Before Taraweeh	15%
After Taraweeh	15%
Before sleeping	10%
At suhoor (sehri)	20%
Just before suhoor ends	10%

Tips for a hydrated fast:

• Choose water, milk, chaas and coconut water. Include soup, fruit and cucumber, which count toward your total.
• Eat a suhoor with protein and fibre, and go easy on salty and fried foods that make you thirsty.
• Limit tea and coffee, and avoid sugary drinks as your main source.
• Keep daytime activity light and rest in the shade.
• Speak to your doctor about fasting if you have kidney disease, diabetes, heart disease or are pregnant.

Does Tea, Coffee and Other Drinks Count?

Yes. Moderate amounts of tea and coffee contribute to your fluids, and so do milk, lassi, chaas, coconut water, soups and juices. Water is still the best default because it has no sugar or calories. Sweetened drinks add up quickly, so keep them small.

Water-Rich Foods

About one-fifth of your water comes from food. Foods that help:

Food	Water content (approx.)
Cucumber	95%
Tomato	94%
Watermelon	92%
Orange	86%
Curd (dahi)	85% to 88%
Milk	87%
Cooked rice	65% to 70%

Signs You May Be Dehydrated

• Dark yellow or amber urine
• Dry mouth, headache or dizziness
• Tiredness and trouble concentrating
• Muscle cramps
• Passing little urine

In hot weather or severe vomiting and diarrhoea, dehydration can become serious. Heat exhaustion with confusion, a very fast pulse or a high temperature needs urgent medical care.

Can You Drink Too Much Water?

Yes, though it is uncommon. Drinking very large amounts quickly can dilute your blood sodium, a condition called hyponatremia. A healthy adult’s kidneys can handle roughly 800 ml to 1 litre of water an hour, so keep each hour below about 1 litre. People with kidney, heart or liver conditions may have a fluid limit and must follow their doctor’s advice.

Water and Weight Loss

Water does not burn fat, but it helps in practical ways:

• A glass before meals can reduce how much you eat.
• Swapping sugary drinks for water cuts calories without effort.
• Thirst can be mistaken for hunger.

Pair your water plan with our Calorie Deficit Calculator and BMR and TDEE Calculator.

Simple Habits to Drink More Water

1. Start the day with a glass as soon as you wake up.
2. Keep a bottle where you work and sit.
3. Link drinking to habits: after prayers, after brushing, before each meal.
4. Flavour water with lemon, mint or cucumber.
5. Use the schedule from the calculator and set reminders.
6. Check your urine colour. Pale yellow means you are on track.

Common Mistakes

• Waiting until you feel thirsty, especially in older age
• Drinking only a few big bottles at once
• Skipping extra water on hot days and workout days
• Counting sugary drinks as your main water
• Drinking large amounts right before bed
• Copying a number such as “4 litres” without considering your size and health

Related Calculators

• Calorie Deficit Calculator
• BMR and TDEE Calculator
• Protein Intake Calculator
• Macro Calculator
• BMI Calculator
• Body Fat Percentage Calculator

Frequently Asked Questions

How much water should I drink a day?

A good starting point is about 33 ml per kg of body weight, then more for exercise and hot weather. For many adults this is between 2 and 3.5 litres of drinks a day. The calculator gives your exact figure.

Is 3 litres of water a day too much?

Not necessarily. For a larger, active person in hot weather, 3 litres or more can be normal. For a small, inactive person in a cool climate it may be more than needed.

How many glasses is 2 litres of water?

Eight glasses of 250 ml.

How much water should I drink in summer?

Add about 0.5 litre in warm weather and about 1 litre in hot, humid weather on top of your normal amount, and more if you exercise.

How much water should I drink during Ramadan?

The same total amount as on other days, spread between iftar and suhoor. A common split is smaller amounts every hour or so from iftar to bedtime, plus a good drink at suhoor.

Does drinking water help with weight loss?

It can help indirectly by reducing sugary drinks and sometimes appetite, but it does not burn fat on its own.

How much water should I drink while exercising?

Roughly 400 to 800 ml per hour, depending on your sweat rate. Weigh yourself before and after training: every kilogram lost is about one litre of fluid to replace.

Does tea or coffee count as water?

Yes. Moderate tea and coffee count toward your fluid intake.

What is the best time to drink water?

Spread it through the day: when you wake up, before meals and around exercise. Reduce it in the 90 minutes before bed.

How do I know if I am drinking enough?

Your urine should be pale yellow and you should rarely feel thirsty.

Is it safe to drink too much water?

Very large amounts in a short time can be dangerous. Stay below about 1 litre per hour.

Final Thoughts

The right amount of water depends on your body, your day and your weather. Use the calculator for a personal target, spread it across the day, watch your urine colour and adjust on hot or active days.

Medical disclaimer

This calculator and article are for education only and are not medical advice. If you have a health condition that limits fluids, or you take diuretics, follow your doctor’s guidance.