Quick quiz: what percent of the human body is water? If you said 70, you’re in good company, because that’s the number a lot of us got taught and never questioned. I said 70 for years. It turns out to be a bit high for grown-ups.
For most adults the real answer sits around 55 to 60 percent, with men near the top of that range and women near the bottom. Babies are the ones up around 70 and beyond. The rest of this post covers who has more, who has less, what your organs are made of, and what all of it means for how much you should drink.
What Percent of the Human Body Is Water on Average?
The U.S. Geological Survey says up to 60 percent of an adult’s body is water. Other sources say 50 to 65, and honestly they’re all describing the same thing, since your exact number depends on your muscle, your fat, and even what kind of day you’re having.
Let us visualize this concept. For example, a man who weighs 150 pounds has 60 percent of water in his body, meaning he has approximately 90 pounds of the fluid in him. That is equal to approximately 11 gallons of water. Think about having 11 gallons of milk in your kitchen. The same logic can be applied to understand how difficult training in hot weather causes a person to feel exhausted because he might lose a number of pounds while sweating.
Human Body Water Percentage by Age
Babies win. A newborn is about 78 percent water, and by the first birthday, that’s down to around 65. After that it tends to keep sliding, slowly, for the rest of your life. I suspect that’s where the 70 percent myth comes from. It’s close to the baby and little kid number, and somewhere along the way people started applying it to everybody.
Mayo Clinic has pointed out that older adults can feel less thirsty than they used to. If that’s you, or someone you look after, drinking on a schedule beats waiting for your body to complain.
Body Water Percentage in Men vs. Women
Men average around 60 percent, and women around 55. Before anyone gets the wrong idea, this has nothing to do with who drinks more water. It’s about body makeup.Muscle is wet, while fat is relatively dry, and females tend to have higher body fat than males. That same reasoning accounts for how two individuals with the same body weight may end up with different results and how an extremely muscular individual might score above average.
Water Percentage in the Brain, Heart, and Other Organs
This part is my favorite because the numbers are strange. The USGS points to a 1945 study that put the lungs at about 83 percent water, muscles and kidneys at about 79, the brain and heart at about 73, and skin at about 64. Bones, which feel like the driest thing in you, are around 31 percent.
So roughly three quarters of your brain is water. I’m not saying that’s why you can’t think straight after skipping your morning glass, but I wouldn’t rule it out.You can find more everyday body facts, including what percent of the human body is water breakdown, on Calm Health Tips.
Why Your Body Needs So Much Water
It is not just lying there. Water distributes nutrients in your blood, helps cool you off through sweating, protects your brain and spinal cord, lubricates your joints, and eliminates waste from your body.That’s the USGS list, and I’d add that most of us only think about water on a hot day or after a workout. But you lose it constantly, just by breathing and going to the bathroom, and Mayo Clinic says you have to keep replacing it with drinks and with foods that contain water.
Signs of Dehydration
You’ll usually feel thirsty first, though not always. I’d rather you catch it early than late, because tiredness and headaches are easy to blame on anything except water. A dry mouth, a headache, feeling wiped out or a little dizzy, and darker yellow urine are other common signs. The urine check is the easy one.According to Mayo Clinic, when you don’t feel thirsty often and your urine is light yellow or colorless, chances are that you are fine.
Heat, strenuous exercise, and illnesses like fever, vomiting, and diarrhea all make you dehydrated quickly; therefore, it’s when you should take water purposely. Minor cases will improve by taking fluids. When confusion, fainting, fast heart rate, or difficulty urinating, seek help immediately.
How Much Water Should I Drink a Day?
This is where people expect one clean number, and there isn’t one.
According to the USGS, 3 liters of fluid intake daily is needed for men and 2.2 liters for women, taking into account food products. The Mayo Clinic states that your individual water needs depend on your state of health, activity, and location. An individual working out in the open air in July in Phoenix has other water needs than a person who stays in an office in Seattle in March.
Don’t forget food. A soup bowl, some grapes, or cucumber slices all have water content. Your cup of water does not satisfy your needs in respect to water. Eight glasses a day of drinking water is a sensible figure, but not an obligation. Tea, milk, soup, fruits and veggies all contain water. To make things easier, drink a glass whenever you eat and sweat. Though, in some cases, an excessive water intake may turn out problematic, this is very unlikely for a healthy person. Consult your doctor about water amount in case of kidney or heart issues.
Your Next Step
So, what percent of the human body is water? Roughly 60 for most adult men, 55 for most women, and a lot more for babies. I wouldn’t obsess over the exact number. Try this instead: put a bottle where you’ll see it, and peek at your urine color a couple of times a day for a week. It’s a little gross, and it works. If you want more on human body water percentage and everyday hydration, Calm Health Tips has plenty.
FAQ
What percent of the human body is water?
Up to 60 percent for the average adult, according to the USGS. Men are around 60 percent, and women around 55 percent. Babies start higher, at about 78 percent.
Is the human body 70 percent water?
Not for most adults. That number is closer to what babies and young kids have. Grown-ups usually land between about 55 and 60 percent.
Which organ has the most water?
Of the organs the USGS lists, the lungs are highest at about 83 percent. Muscles and kidneys come next at about 79 percent, then the brain and heart at about 73 percent.
Can you drink too much water?
Yes, but it’s rare in healthy adults. Mayo Clinic explains that your kidneys can’t clear extra water if you drink far too much. Athletes and people with certain health conditions should follow their doctor’s advice.
