A medium ear of sweet corn has roughly 90 calories, while a large ear (about 7¾ to 9 inches long) comes in at around 123 calories. That puts corn in the same ballpark as a medium banana or a small baked potato, making it a moderate-calorie whole food despite its reputation as a “starchy” vegetable.
Calories by Serving Size
How many calories you get from corn depends mostly on how much you eat and what form it’s in. A large ear of raw yellow sweet corn contains about 123 calories, 27 grams of carbohydrates, nearly 5 grams of protein, and under 2 grams of fat. It also delivers close to 4 grams of fiber. A cup of loose corn kernels, the kind you’d scoop onto a plate, has roughly 85 calories, largely because you’re eating less total corn than a full ear provides.
Canned corn is similar in calorie content to fresh corn, though it often contains added sodium or sugar depending on the brand. Frozen corn is typically flash-frozen without additives and stays close to the fresh calorie count.
How Cooking Method Affects Calories
Boiling, steaming, or grilling an ear of corn does not meaningfully change its calorie count on its own. The calories shift only when you add butter, oil, mayo, or other toppings. A tablespoon of butter adds about 100 calories, effectively doubling the calorie content of a small ear. If you’re tracking intake, the corn itself isn’t the variable. It’s what goes on top.
Popcorn vs. Sweet Corn
Popcorn and sweet corn come from different varieties of the same plant, and their calorie profiles reflect that. Three cups of air-popped popcorn contain fewer than 100 calories and about 4 grams of fiber, making it one of the lowest-calorie snack foods by volume. Sweet corn is denser and higher in moisture, so a single cup of kernels has around 85 calories but fills a much smaller bowl. If you’re looking for a high-volume, low-calorie snack, plain popcorn wins. But sweet corn delivers more vitamins and a broader nutrient profile per serving.
How Corn Compares to Other Starches
Corn and potatoes are nearly identical in calories: 96 versus 93 per 100 grams. The difference is in the type of carbohydrate. Potatoes pack more than twice the starch (17 grams per 100g compared to corn’s 7 grams), while corn has more fiber and natural sugar. White rice, for reference, runs about 130 calories per 100 grams when cooked, making corn a lighter option if you’re substituting it as a side dish.
Compared to other common vegetables like broccoli (34 calories per 100g) or green beans (31 calories per 100g), corn is noticeably higher in calories. That’s because it’s technically a grain when mature and a vegetable when harvested young. Its starchy nature puts it in a middle zone between leafy vegetables and grains.
Fiber, Blood Sugar, and Satiety
Despite being starchy, sweet corn is a low-glycemic-index food. Its fiber is primarily the insoluble type, which slows digestion and prevents the kind of rapid blood sugar spike you’d get from refined carbohydrates like white bread. For people managing diabetes, a useful rule of thumb from Mayo Clinic: half a cup of corn kernels, or one small ear, contains about 15 grams of carbohydrate, which counts as one carbohydrate serving.
That fiber also contributes to fullness. An ear of corn with 4 grams of fiber and 5 grams of protein is more satisfying than its calorie count alone might suggest. You’re unlikely to overeat plain corn the way you might overeat chips or crackers with similar calorie density, simply because the fiber and water content slow you down.
Practical Calorie Estimates at a Glance
- Small ear of corn (6 to 7 inches): about 85 calories
- Large ear of corn (7¾ to 9 inches): about 123 calories
- 1 cup of corn kernels: about 85 calories
- 3 cups air-popped popcorn: under 100 calories
- 1 tablespoon of butter on corn: adds roughly 100 calories