How many calories are in one oyster mushroom?

Oyster mushrooms are a delicious and nutritious variety of edible mushroom. When trying to follow a healthy diet or manage your weight, knowing the calorie content of different foods can be helpful. So how many calories are contained in just one oyster mushroom?

The Basics of Oyster Mushroom Nutrition

Oyster mushrooms (Pleurotus ostreatus) are an edible variety of mushroom that have a mild, delicate flavor. They are often described as having a subtle sweetness. Oyster mushrooms grow in clusters on hardwood logs or stumps and have caps that range from pale gray to pale brown in color.

Oyster mushrooms contain a variety of vitamins and minerals that provide nutritional benefits. Some of the nutrients found in oyster mushrooms include:

  • B vitamins like riboflavin, folate, and niacin
  • Vitamin D
  • Vitamin C
  • Potassium
  • Copper
  • Phosphorus

Like other varieties of mushrooms, oyster mushrooms are naturally low in calories and fat. A standard serving size of 80g or around 5 medium oyster mushroom caps contains just:

  • 22 calories
  • 0.3g fat
  • 3.9g carbohydrates
  • 2.7g protein

Knowing the full nutritional breakdown of oyster mushrooms per serving provides useful information. But if you simply want to know how many calories are contained in a single average-sized oyster mushroom cap, calculating that specific calorie count requires a few additional steps.

Determining the Weight of One Oyster Mushroom

Nutritional information like calories is typically provided for standard serving sizes or per 100g of a given food. To determine the calories in just one oyster mushroom, you first need to know approximately how much a single cap weighs.

The size and weight of individual oyster mushroom caps can vary based on factors like the stage of maturity when picked and general growing conditions. However, most full-sized medium oyster mushroom caps are around 10-15g each.

For the purposes of this nutritional calculation, let’s assume the average oyster mushroom cap weighs approximately 12g.

Performing the Calorie Calculation

Now that we know the average weight of one oyster mushroom cap, we can use the nutritional information provided for a standard 80g serving size to calculate the calories for 12g:

  • There are 22 calories in 80g of oyster mushrooms
  • To find the calories in 12g, divide the calories per serving by the serving size and multiply by 12g
  • ((22 calories / 80g) x 12g) = 3.3 calories

So for an average-sized oyster mushroom cap weighing around 12g, the total calories comes out to approximately 3 calories.

Calorie Calculation for Small, Medium and Large Oyster Mushroom Caps

To provide a calorie range for oyster mushroom caps of different possible sizes, here is a breakdown of the estimated calories for small, medium and large caps:

Mushroom Cap Size Approx. Weight Calories
Small 8g 2 calories
Medium 12g 3 calories
Large 16g 4 calories

As you can see, even for a larger oyster mushroom cap, the calorie count remains very low, ranging from just 2 to 4 calories per mushroom.

Calories for Multiple Oyster Mushrooms

Oyster mushrooms are often cooked and served in quantities of more than one mushroom at a time. So how many calories would, for example, 10 oyster mushrooms contain?

Using the nutritional information we already calculated:

  • 1 medium oyster mushroom (12g) = 3 calories
  • 10 medium oyster mushrooms (10 x 12g) = 120g
  • ((22 calories / 80g) x 120g) = 33 calories

Therefore, approximately 33 calories would be found in 10 medium-sized oyster mushroom caps.

Factors That May Impact Calorie Content

It’s important to note that the calorie estimates provided above are approximations. The exact calorie content of oyster mushrooms can vary slightly due to factors like:

  • Exact size and weight, which can fluctuate naturally
  • Stage of maturity when picked
  • Moisture content
  • Growing conditions impacting size and density
  • How the mushrooms are prepared – raw, cooked, grilled, etc.

While these factors mean the calories per mushroom may not always be exactly the same, the differences are usually minimal. Overall, oyster mushrooms consistently provide very low amounts of calories per mushroom.

The Benefits of Adding Oyster Mushrooms to Your Diet

In addition to being low in calories, oyster mushrooms offer many benefits:

  • Nutrient-dense – Excellent source of B vitamins, vitamin D, copper, and other nutrients
  • Support immune function – Contain AHCC, a compound that boosts protective immune cells
  • Help regulate cholesterol – Have cholesterol-lowering properties
  • Anti-inflammatory effects – Linked to reducing inflammation
  • Source of antioxidants – Contains antioxidants like ergothioneine

Oyster mushrooms are widely available, affordable, and easy to cook. They have a mild flavor that works well in many dishes. Adding more oyster mushrooms to your meals and recipes is an easy way to boost nutrition without significantly increasing calorie intake.

Cooking and Serving Ideas for Oyster Mushrooms

Oyster mushrooms are very versatile in the kitchen. Here are some ideas for enjoying their mild, delicate flavor:

  • Sauté in olive oil and add to omelets or scrambled eggs
  • Stir-fry with snap peas, bell peppers and chicken or tofu
  • Skewer and grill, then use in kebabs or on top of salads
  • Roast in the oven until lightly browned and pair with fish or chicken
  • Add to pizza, tacos, sandwiches, soups, pasta dishes, and casseroles
  • Braise or simmer in wine, vegetable broth, or soy sauce for rich flavor

Their neutral taste allows oyster mushrooms to work well in both savory and sweet dishes. They provide an extra boost of nutrients and texture while adding minimal calories.

Should You Include More Oyster Mushrooms in Your Diet?

If you are looking for ways to boost nutrition without a lot of extra calories, oyster mushrooms are an excellent choice. Just a single oyster mushroom contains only 2-4 calories, so you can add lots of extra mushrooms to your diet without making a significant impact on your daily calorie intake.

Combined with their stellar nutritional profile and ease of use in recipes, the low calorie content makes oyster mushrooms a great addition to any healthy, balanced diet. Taking advantage of their many benefits only requires creatively coming up with more ways to enjoy their delicious, mild taste.


When seeking to manage calories or eat nutrient-dense foods, knowing the nutrition information for individual foods allows you to make informed choices. An average medium oyster mushroom cap contains just 3 calories, making oyster mushrooms an essentially calorie-free way to obtain important vitamins, minerals, antioxidants and other beneficial compounds.

While the exact calorie count may vary slightly, oyster mushrooms consistently provide minimal calories and valuable nutrition, making them a healthy addition to any diet.

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