Is a watermelon 99% water?

Watermelons are famously known for being made up almost entirely of water. The common belief is that watermelons are 99% water, meaning the fruit is extremely hydrating and nutritionally hollow. But is this actually true? Are watermelons really 99% water?

What Percentage of a Watermelon is Actually Water?

The exact water percentage of a watermelon varies slightly depending on the variety, but the average water content falls somewhere between 92-95%. So no, watermelons are not 99% water. That statement is a bit of an exaggeration.

Here is a breakdown of the basic nutritional composition of 1 cup of watermelon (with rind removed):

Nutrient Amount Daily Value
Calories 46 2%
Total Fat 0.23 g 0%
Cholesterol 0 mg 0%
Sodium 1.41 mg 0%
Total Carbohydrate 11.5 g 4%
Dietary Fiber 0.4 g 2%
Sugars 9.42 g N/A
Protein 0.61 g 1%
Vitamin A 942 IU 19%
Vitamin C 12.3 mg 20%
Calcium 8 mg 1%
Iron 0.24 mg 1%
Water 91.5 g N/A

As you can see, water makes up about 92% of the watermelon’s weight. The other 8% is comprised of carbs, vitamins, minerals, and a tiny amount of protein and fat. So watermelons are very high in water, but not 99% H2O.

Where Does the 99% Water Myth Come From?

So how did this myth that watermelons are 99% water come about? There are a few potential origins:

Watermelons are over 90% water, so 99% is a bit of an exaggeration but along the right lines. The high water percentage probably got rounded up at some point.

The rind was included in the analysis. The rind of a watermelon contains much less nutrients than the red flesh. If you include the rind in the calculations, this pushes the water percentage even higher.

Comparisons to other fruits. Watermelons do contain significantly more water than most other fruits and vegetables. For example, strawberries are around 91% water, while cucumbers are 96% water. So in comparison to other produce, it’s easy to see how watermelons got the 99% label.

Nice, round number. 99% is a nice clean number that’s easy to remember. It’s catchier than saying watermelons are 92-95% water.

So while watermelons are extremely hydrating, the 99% water figure is a bit exaggerated. But it makes for a good factoid and shows how water-dense this fruit is compared to alternatives.

Watermelon Water Percentage Varies by Variety

While the average water content is around 92%, there can be slight variation in water density depending on the watermelon variety.

Some watermelon varieties have higher or lower water concentrations based on factors like:

Flesh color – The redder the flesh, the higher the water content. Pink or yellow flesh contains slightly less.

Seedless vs seeded – Seedless varieties tend to have a higher percentage of water.

Average size – Smaller watermelons with a higher flesh to rind ratio contain more water than bigger melons.

Growing conditions – Drought conditions can cause melons to have higher water densities. Ideal hydration leads to slightly less water content.

So while the standard water percentage is 92-95%, certain varieties may range from 90-96%. But no watermelon is truly 99% water.

Watermelons Have High Nutritional Value

Despite the very high water composition, watermelons are still fairly nutrient dense.

Some of the key nutrients found in watermelon flesh include:

Vitamin C – One cup contains 20% of the RDI of vitamin C. This aids immune function and acts as an antioxidant.

Vitamin A – Watermelon gets its red color from the antioxidant lycopene, which the body converts into vitamin A. One cup provides 19% of the RDI.

Potassium – With 170mg per cup, watermelon is an excellent source of potassium. This mineral is important for heart health, fluid balance, and muscle function.

Lycopene – This powerful antioxidant gives watermelon its signature red color. Lycopene has been linked to lower risk of certain cancers.

Citrulline – Watermelon contains high levels of citrulline, an amino acid that may improve exercise performance and lower blood pressure.

So while water is the predominant component, watermelon still packs a nutritious, antioxidant-rich punch. The vitamins, minerals, and beneficial plant compounds complement the hydrating quality of this summertime fruit.

Watermelons Have a High Water Density

One other reason people may associate watermelons with being 99% water is due to their very high water density.

Water density compares the amount of water per unit volume in a food. Most fruits and vegetables are 80-95% water by weight, but they have varying water densities.

For example, one cubic centimeter of watermelon contains about 0.93 grams of water. Compare that to spinach, where 1 cc contains 0.95 grams of water.

So by volume, watermelon has a very high concentration of H2O. The flesh is packed with water, giving watermelon its low calorie density of just 0.3 calories per gram.

This high water density contributes to that feeling of water “bursting” out of a watermelon once you bite into it. The liquid is very tightly packed into the plant cells.

So while not 99% water, watermelon does uniquely hydrate and quench thirst thanks to this high water density.

Water Content Declines as Watermelon Ripens

Early in development, watermelons have closer to 95% water content. But as the melon ripens and grows larger, the percentage drops bit by bit.

When the fruit is fully ripe, the water concentration typically ranges from 90-94%.

Here’s an approximate water percentage breakdown as a watermelon ripens:

Ripeness Water %
Immature white 95%
Mostly white 94%
Light pink 93%
Pink throughout 92%
Deep red 90-91%

As sugars develop and the flesh softens and expands, the concentration gradually decreases. But even when fully ripe, watermelons still provide excellent hydration.

Watermelon Juice is Extremely Hydrating

When made into juice, the water density of watermelon is extremely high.

Since juicing removes all the flesh while retaining just the liquid, watermelon juice ends up being closer to 99% water. It’s one of the most hydrating juice options.

An 8oz glass of watermelon juice typically contains:

Nutrient Amount
Water 7.5 oz
Sugar 18 g
Vitamin C 20% DV
Vitamin A 18% DV
Potassium 8% DV

With only around 1.5 ounces coming from natural sugars and a traces of vitamins, juice truly squeezes out the high water content of watermelon.

Watermelon juice has a water percentage in the high 90s. It has an even higher water density than the whole fruit.

Eating Watermelon Helps the Body Hydrate

Research has shown that eating water-rich fruits and vegetables effectively contributes to hydration.

While drinking water is critical to maintain fluid balance, food can also be a valuable source of hydration. This is especially true during exercise.

One study showed that eating watermelon helped maintain hydration just as well as drinking a sports drink during intense exercise in athletes. The athletes consumed either watermelon juice or sports drink during cycling trials and had similar heart rate, temperature, and hydration levels.

Another study gave athletes watermelon in the form of a smoothie or juice after exercising. Consuming watermelon helped restore body water levels and relieve muscle soreness just as well as drinking plain water.

So while water is the gold standard, eating water-dense produce like watermelon provides the body with extra hydration. The water content is released during digestion and absorbed into the bloodstream.

Tips for Maximizing Watermelon Hydration

Watermelon can be a very effective way to meet daily fluid needs, especially in warm weather. Here are some tips for getting the most hydration from watermelon:

– Choose ripe, deep red melons – the redder the inside, the higher the water content

– Eat watermelon chilled – cool temperature allows for faster water absorption

– Consume early in the day – watermelon hydration is best on an empty stomach

– Pair with a source of electrolytes like a pinch of salt or sports drink to retain more water

– Leave wedges in the fridge so it’s always ready for quick hydration

– Juice or blend to maximize fluid volume compared to just flesh

– Add some chia or basil seeds to make “watermelon water” and create an electrolyte boost

– Infuse water with watermelon overnight to make fruity hydrating water

While not quite 99% water, properly prepared watermelon can be one of the most effective sources of hydration during hot weather and physical activity.


Watermelons are certainly high in water, but the 99% water figure is slightly exaggerated. Most varieties range between 90-95% water once fully ripe.

While not completely devoid of nutrients and fiber, watermelon’s high water content and density make it an excellent choice for hydration. Watermelon juice in particular packs a super hydrating punch.

So next time you’re seeking quick hydration, reach for watermelon as a tasty way to get some extra H2O. Even if not quite 99% water, it will get you significantly closer to meeting your daily fluid needs.

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