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Water Intake Calculator - your weight and activity level

Use our Water Intake Calculator to find out how much water you should drink daily based on your weight and activity level. Supports both US and Metric units.

Recommended Daily Water Intake

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Water Intake Calculator

What is Water Intake Calculator?

Water Intake Calculator is an online tool that determines how much water you should drink per day based on your weight and daily physical activity level.
More than 60% of our bodies are made up of water, so drinking the right amount of water every day is essential for a healthy lifestyle.

This tool works in two units:

  • US Units: Weight in lbs and results in oz/day

  • Metric Units: Weight in kg and result in liters/day

 How this tool works?

This calculator works based on a specific formula.
In US units, this formula usually looks like this:

Daily Water Intake(oz) = Body Weight(lbs) × 0.67 + (Activity Factor × Body Weight)

Where the Activity Factor is 0.4 (light exercise), 0.6 (moderate), 0.8 (heavy).
That is, the more active you are, the more water your body needs.

In Metric units:

Daily Water Intake(liters) = Body Weight(kg) × 0.033 + (Activity × 0.01 × Body Weight)

This is a scientifically supported formula. Other medical institutions, including the Mayo Clinic, also use this type of calculation to provide water intake guidelines.
Reference: Mayo Clinic - Water: How much should you drink every day?

Example Calculation

Let's say a person weighs 183 pounds and has an activity level of "Little to no exercise", then their water needs would be:

183 × 0.67 = 122.6 oz/day

This means that he needs to drink at least 122.6 fluid ounces of water per day, which is about 3.6 liters.

Why proper hydration is important?

⏺ What can happen if you don't drink enough water:

  • Dizziness and fatigue

  • Digestive problems

  • Dry skin

  • Kidney problems

  • Attention deficit

⏺ And if you drink enough water regularly:

  • Body temperature is normal.

  • Blood circulation is better.

  • Helps digestion.

  • Losing weight is easier (water boosts metabolism)

How to understand the result

If your calculator result is:

  • 122.6 oz/day (US units) means your body needs
    about 3.6 liters of water a day.

  • 2.7 liters/day (Metric units)
    So you need to understand that this much water is needed according to your weight.

Tips:
Instead of drinking this amount of water straight away, drink it gradually throughout the day. You can measure it out in a water bottle to meet your daily target.

Who should use this calculator?

This calculator is especially useful for:

  • If you want to lose weight

  • If you go to the gym/exercise

  • For people who drink less water

  • Staying hydrated in summer

  • Those who are pregnant or nursing mothers (extra hydration needed) Final Words

Water Intake Calculator is a simple way to understand your water needs and stay hydrated. While it is not a medical diagnosis, it is a very useful tool for healthy living.

Remember, in addition to water, your diet, sleep, and physical activity are also important.

Frequently Asked Questions

How can I know how much water I should drink daily?
You can use this calculator based on your weight and daily activity level to find out the right amount of water your body needs. It helps maintain proper hydration balance.
Is drinking too much water harmful?
Yes, excessive water intake may lead to “water intoxication” or “hyponatremia,” which can be dangerous. Stick to the recommended amount provided by the calculator.
Do I need more water if I have an active lifestyle?
Absolutely. The more active you are, the more water your body loses through sweat and activity—so your hydration needs increase accordingly.
What is the difference between Metric and US units?
US Units take weight in pounds (lbs) and show results in ounces/day. Metric Units use kilograms (kg) and return results in liters/day.
Does tea or coffee count as water intake?
Yes, but in moderation. Tea and coffee contain caffeine, which can have a dehydrating effect. Pure water is still the best way to meet your hydration needs.