How many calories are in a portobello mushroom?
One whole raw cap weighs 84 g and carries 18 calories. Per 100 g raw portabella runs 22 calories, which puts a palm-sized mushroom below almost anything else you can put on a plate whole. Grilled, the same mushroom concentrates to 29 calories per 100 g.
On this page
- Portobello mushroom quick facts
- US servings from one ounce to two caps
- Grilled portobello and the other USDA rows
- Potassium is the row that surprises people
- How does a portobello compare?
- Most popular portobello mushroom brands
- FAQ
Portobello mushroom quick facts
The row behind every number here is SR Legacy 169255, "Mushrooms, portabella, raw". It is the only USDA record for plain raw portobello that also carries a household measure people actually use — one piece whole, 84 g. USDA spells the food "portabella"; the grocery sign usually says portobello, and it is the same mushroom.
There is a second candidate, a Foundation market sample, but its calories are calculated by the Atwater factors rather than measured, which lands it higher. It gets its own line further down instead of being blended in. Averaging two USDA records would only produce a number that matches neither.
| Nutrient | Per 100 g | Per one whole cap (84 g) | % Daily Value |
|---|---|---|---|
| Calories | 22 | 18 | — |
| Total fat | 0.35 g | 0.3 g | 0% |
| Saturated fat | 0.01 g | 0.0 g | 0% |
| Carbohydrate | 3.87 g | 3.3 g | 1% |
| Dietary fiber | 1.3 g | 1.1 g | 4% |
| Total sugars | 2.5 g | 2.1 g | — |
| Protein | 2.11 g | 1.8 g | 4% |
| Sodium | 9 mg | 8 mg | 0% |
| Cholesterol | 0 mg | 0 mg | 0% |
| Potassium | 364 mg | 306 mg | 7% |
% Daily Value is based on a 2,000-calorie diet.
Verified nutrition data
Numbers on this page come from USDA FoodData Central, the U.S. Department of Agriculture’s food composition database, and from manufacturer labels where a branded product is named. Last verified September 2026. How we verify our data →
There is no added sugars row because USDA does not measure added sugars for fresh vegetables — all 2.5 g per 100 g is sugar the mushroom grew with. Trans fat is zero and stays out of the table for the same reason. The Daily Values used above are the FDA's current ones, published on the Nutrition Facts label reference page.
US servings from one ounce to two caps
| Serving | Weight | Calories |
|---|---|---|
| 1 oz | 28 g | 6 kcal |
| One whole cap, raw | 84 g | 18 kcal |
| 1 cup diced, raw | 86 g | 19 kcal |
| Two whole caps | 168 g | 37 kcal |
| Per 100 g | 100 g | 22 kcal |
The whole cap and the diced cup are USDA household measures on record 169255. The ounce and the two-cap line are our own arithmetic from the USDA 100 g figure, not USDA servings — useful because most people buy portobellos by the piece and log them the same way.
Notice how close the cup and the cap sit: 86 g diced is 19 calories, one whole 84 g cap is 18. Raw, a cup of diced mushroom is basically one mushroom. That equivalence breaks the moment heat is involved, and it breaks in a direction most people do not expect.
Grilled portobello and the other USDA rows
| Version | Per 100 g | Typical serving | Calories |
|---|---|---|---|
| Raw portobello (main row) | 22 kcal | one whole cap, 84 g | 18 kcal |
| Grilled portobello | 29 kcal | 1 cup sliced, 121 g | 35 kcal |
| UV-exposed portabella, raw | 22 kcal | one whole cap, 84 g | 18 kcal |
| UV-exposed portabella, grilled | 29 kcal | 1 cup sliced, 121 g | 35 kcal |
| Foundation market sample | 32.4 kcal | 100 g | 32 kcal |
Grilling moves the mushroom from 22 to 29 calories per 100 g, and the grill adds nothing at all. Water leaves, the remaining gram of mushroom is denser, and every measured value rises with it: protein 2.11 to 3.28 g, fiber 1.3 to 2.2 g per 100 g. USDA's grilled record is cooked dry, so if you brush the cap with oil first, that oil is a separate entry in your log — it is the only ingredient in the whole process that carries real calories.
This is where the cup trap shows up. One cup of grilled sliced portobello weighs 121 g and comes to 35 calories, nearly double the 19 of a raw diced cup, because a cup holds far more shrunken mushroom than fresh. Measuring by volume after cooking quietly changes what you logged.
The UV rows exist for a different reason. Portabella exposed to ultraviolet light is the same 22 calories raw and 29 grilled; what UV changes is vitamin D, which the NIH Office of Dietary Supplements lists as scarce in plant foods outside treated mushrooms. Nothing about the energy number moves.
Canned portabella is its own animal. US branded cans run 13 to 17 calories per 100 g because they are packed in liquid, while sliced fresh-pack products land near 29. The sodium is the trade: canned rows sit at 339 to 367 mg per 100 g against 9 mg for the fresh mushroom.
Potassium is the row that surprises people
One cap delivers 306 mg of potassium, 7% of the 4,700 mg Daily Value, next to 8 mg of sodium — 0% of the DV, and roughly a 38-to-1 ratio in potassium's favor. Very few foods you can pick up whole are shaped like that. For anyone told to watch sodium, the fresh mushroom is close to free, which is exactly what the canned version undoes.
Fiber is the other quiet line: 1.1 g in a single cap, 4% of the 28 g Daily Value, for 18 calories. MyPlate counts mushrooms in the vegetable group, and on a calories-per-gram basis this is one of the cheapest ways to make a plate look full. If you are building a lunch around 350 to 450 calories, two grilled caps cost you almost nothing of that budget.
Protein is where portobello gets oversold. A cap has 1.8 g. A cup of grilled slices has about 4.0 g. It replaces a burger patty in texture and in the way it holds sauce, not in protein.
How does a portobello compare?
| Vegetable | Per 100 g | US serving | Calories |
|---|---|---|---|
| Portobello, raw | 22 kcal | one whole cap, 84 g | 18 kcal |
| White mushroom, raw | 22 kcal | 1 oz, 28 g | 6 kcal |
| Broccoli raab, raw | 22 kcal | 1 oz, 28 g | 6 kcal |
| Beet greens, raw | 22 kcal | 1 oz, 28 g | 6 kcal |
Our take: all four rows land on exactly 22 calories per 100 g, so calorie counting cannot separate them. What separates them is protein, and portobello finishes last of the four at 2.11 g per 100 g, behind white mushroom's 3.09 g and broccoli raab's 3.17 g. Pick portobello for the size and the texture of a single cap you can grill and eat like a patty. Pick white mushrooms or greens if the goal is protein per gram, and remember the choice barely matters until oil enters the pan.
Most popular portobello mushroom brands in the United States
Ranked by how widely each product appears among foods sold in the United States, from the BodyPal food database of over 3.3 million products. Calories are the figures printed on each Nutrition Facts label, checked against USDA FoodData Central.
| Product | Calories (per 100 g) |
|---|---|
| Giorgio Chunky Portabella Mushrooms | 13 cal |
| Pennsylvania Dutchman Chunky Style Portabella Mushrooms | 17 cal |
| Giorgio D'Lightful Sliced Portabella | 29 cal |
| Garden Highway Portabella Griller | 29 cal |
Brand popularity: BodyPal food database. Nutrition: manufacturer labels / USDA FoodData Central.
Portobello mushroom FAQs
How many calories are in one portobello mushroom cap?
One whole raw cap weighs 84 g and carries 18 calories, at 22 calories per 100 g. That is a very small amount of energy in a piece of food the size of your palm. Two caps together come to 37 calories, and a 1 oz portion is 6.
How many calories in a grilled portobello mushroom?
Grilled portabella runs 29 calories per 100 g, and one cup of grilled slices (121 g) is 35 calories. Nothing is added on the grill; water leaves, so the mushroom weighs less and the per-100-g numbers climb. Oil or butter brushed on the cap is what actually adds calories.
How much protein is in a portobello mushroom?
A whole raw cap holds 1.8 g of protein, 4% of the 50 g Daily Value, and raw portabella is 2.11 g per 100 g. Grilling concentrates it to 3.28 g per 100 g, so a cup of grilled slices delivers about 4.0 g. It is a texture swap, not a protein swap.
How many carbs are in portobello mushrooms?
One raw cap has 3.3 g of carbohydrate, which is 1% of the 275 g Daily Value, and 1.1 g of that is fiber. Per 100 g that is 3.87 g of carbohydrate and 1.3 g of fiber. Total sugars are 2.5 g per 100 g, all of it naturally occurring in the mushroom.
Are portobello mushrooms keto friendly?
Subtract the fiber and one raw cap leaves about 2.2 g of net carbs, our own arithmetic from the USDA figures rather than a USDA value. Per 100 g it works out near 2.6 g. At 18 calories a cap, portobello fits comfortably inside most low-carb daily limits.
Portobello vs white mushroom calories?
They tie: raw portabella and raw white mushrooms are both 22 calories per 100 g, so a 1 oz (28 g) handful of either is 6 calories. White mushrooms carry slightly more protein, 3.09 g per 100 g against 2.11 g, while portobello carries more carbohydrate, 3.87 g against 3.26 g.
Do portobello mushrooms have vitamin D?
The calorie count does not change: portabella exposed to ultraviolet light is still 22 calories per 100 g raw and 29 grilled. UV treatment raises vitamin D only. The NIH Office of Dietary Supplements lists UV-exposed mushrooms among the few plant foods that supply the vitamin at all.
Is portobello mushroom good for weight loss?
At 18 calories a cap and 22 per 100 g, portobello is one of the cheapest ways to fill a plate. A cap brings 1.1 g of fiber and 306 mg of potassium, 7% of the Daily Value, for almost no energy. It supplies bulk and water, which is why it works as a burger cap.
Similar foods
- Mushrooms — 15 cal per cup sliced
- Salad — 23 cal per side salad
- Cabbage — 22 cal per cup chopped
- Cauliflower — 27 cal per cup chopped
- Bell Pepper — 31 cal per medium
- Bell Pepper — 24 cal green, 31 red
Count it without the math
Point the camera at the plate and BodyPal counts the cap, the slices and the oil you cooked them in.
