
Are Water Needs Created Equal? How To Calculate Your Ideal H2O Intake
All of the body’s organs, tissues, cells, and muscles are composed of some percentage of water. The brain and heart are made up of roughly 73% water, the lungs about 83%, the skin 64%, and the muscles and kidneys 79%. Even your bones are made up of 31% water! When all those figures are put together, it becomes apparent that over half the human body is made up of water – roughly 60%, to be exact.
Considering that each and every part of the body needs water to function, it’s obvious that hydration is of the utmost importance when it comes to staying healthy. But why is hydration so important, exactly? And how can you figure out how much you need to drink to stay properly hydrated? Read on to find out how to calculate your ideal H2O intake.
Why is hydration so important?
Water is a vital component in many bodily processes. It helps to control and regulate body temperature, it keeps the joints lubricated (which helps prevent damage), and it can even help prevent infections. Daily water intake also plays a role in how efficiently the body runs when it comes to delivering nutrients to cells and the proper functioning of organs. Being adequately hydrated also plays a role in sleep quality, mood, and cognitive brain functioning.
Many people drink water only when they feel thirsty. But the problem with the thirst signal response is that if you’re feeling thirsty, your body is already dehydrated. It is your brain’s way of telling you that you are experiencing dehydration and you need water immediately.
How much water should you drink per day?
While various experts suggest particular average amounts of water each person should be consuming daily, those averages are only meant as a jumping-off point. According to an article by the Harvard T.H. Chan School of Public Health, the average woman requires 11 cups of water per day, while the average man needs 16. The thing about these averages is that they don’t take into account other factors such as body size, the amount of exercise a person gets, illnesses they may have, or whether or not they consume a lot of caffeine.
The reason these additional factors need to come into play is because of the way they affect the output of your body’s water stores. For example, a person who exercises for 2+ hours per day is going to need much more water than someone who doesn’t exercise at all. This is because exercise drives water loss through sweat, and this lost water needs to be replenished to avoid dehydration.

Image by Marvin Meyer on Unsplash: Active people need more water than people who lead more sedentary lifestyles.
What you eat and drink also play a role in your hydration levels. Caffeine, for example, can act as a diuretic. This means that it prompts the body to create more urine – leading to you losing more water after you consume it. Research shows that by promoting more urination, caffeine can actually dehydrate you and leave your water stores off balance.
Foods that are high in sodium can also lead to more water loss and dehydration, so if you drink a lot of caffeine or eat foods high in salt on a daily basis, your water intake needs will be higher than the “average” person’s.
How much water should I drink based on my weight?
Another factor that comes into play is body size or weight. Did you know that drinking too much water can lead to something called overhydration? This occurs when the kidneys cannot get rid of excess water fast enough, leading to symptoms such as headache, nausea and vomiting, confusion, or disorientation. That is why it’s vital to know how much you should be drinking based on your weight. For example, a person who weighs 100 pounds will not need to drink as much water as someone who is double that size. They may be at risk of becoming overhydrated if they did.
How do I calculate my ideal water intake?
There are many ways you can calculate your own person water intake. If you are basing it on your weight, experts say that a good general rule of thumb is to drink half an ounce to an ounce of water for each pound. That means that if you weigh 175 pounds, you should be drinking anywhere from 88 to 175 ounces per day. You also have to take into account your activity level, the other foods you eat, and your sex.
To calculate your personal water intake based solely on body size and exercise level, you can do the following calculation:
- Your weight x 0.5 = The number of ounces you should be drinking
- Every 30 minutes of exercise = 12 additional ounces of water per day
For example, if you weigh 150 pounds and exercise for 60 minutes every day, you would calculate like this:
- 150 x 0.5 = 75
- 12 ounces x 2 (60 minutes of exercise) = 24 ounces
- Recommended total water intake = 99 ounces per day

Image by Rodion Kutsaev on Unsplash: You can get some of your daily water intake from the foods that you eat.
How to make sure you stay hydrated
Staying hydrated doesn’t just mean drinking water. Many foods are actually a good source of water – for example, grapefruit, broccoli, watermelon, and lettuce are all made up of over 90% water! Eating one serving of each will add a fair amount to your daily water intake. Other ways you can ensure you’re getting enough water include downloading water reminder apps or using other fitness and wellness devices that remind you when it’s time to take another sip.
Drinking enough water throughout a busy day can be difficult – it’s one of those things that’s easy to forget about until you feel thirsty. But remember, if you’re feeling thirsty, you’re already dehydrated. Get your water intake up throughout the day to avoid dehydration and that thirsty feeling altogether.
Featured image by Engin Akyurt on Unsplash