A medium sweet potato has roughly 100 to 110 calories. A large one (about 180 grams) comes in at 162 calories. These numbers shift depending on size and how you cook it, but plain sweet potato is a low-calorie, nutrient-dense food no matter how you prepare it.
Calories by Size and Serving
Sweet potatoes vary quite a bit in size, so calorie counts depend on what you’re actually eating. Per 100 grams of cooked, boiled sweet potato, you’re looking at 76 calories, 18 grams of carbohydrates, 1 gram of protein, and almost no fat (0.1 grams). That’s the baseline number to work from.
Here’s how that scales with common portions:
- Half a cup raw (about 65g): 86 calories
- One large sweet potato (180g): 162 calories
- One cup baked (200g): 180 calories
- One cup boiled and mashed (328g): 249 calories
The mashed cup looks like a calorie jump, but it’s not. A cup of mashed sweet potato weighs significantly more than a cup of cubed or baked sweet potato because it packs together more densely. Gram for gram, the calorie content stays similar.
How Cooking Changes the Numbers
Baking, boiling, and steaming a sweet potato all produce slightly different calorie densities, mostly because of water content. A boiled sweet potato absorbs water during cooking, making it heavier per serving. A baked sweet potato loses water, concentrating its calories into a lighter package. The total calories in the potato itself don’t change much, but the calories per gram shift enough to notice if you’re weighing your food.
For reference, a 200-gram serving of baked sweet potato contains about 180 calories with 151 grams of water. The same weight of boiled sweet potato would have fewer calories per gram because it holds more moisture (about 80% of its weight is water after boiling). If you’re tracking calories closely, weigh your sweet potato raw for the most consistent measurement.
Deep frying is a different story entirely. Sweet potato fries absorb oil during cooking, which can double or triple the calorie count compared to the same amount of plain baked sweet potato. Adding butter, brown sugar, or marshmallows to mashed sweet potatoes similarly pushes the calories well beyond what the potato alone provides.
Sweet Potato vs. White Potato
Calorie-wise, sweet potatoes and white potatoes are nearly identical. A medium baked white potato runs about 160 calories, right in the same range as a large sweet potato. The real difference is in what else you’re getting. One baked sweet potato delivers 156% of your daily vitamin A needs, thanks to the beta-carotene that gives it that orange color. White potatoes have almost none.
Sweet potatoes also have a moderate glycemic index. Steamed, baked, and microwaved sweet potatoes all score in the range of 63 to 66 on the glycemic index scale, placing them squarely in the “moderate” category. That means they raise blood sugar more gradually than white bread or white rice, though the difference between cooking methods is minimal.
Why Sweet Potatoes Fill You Up
At 76 calories per 100 grams, sweet potatoes are one of the more satisfying foods you can eat relative to their calorie cost. Their carbohydrates include a meaningful amount of fiber, which slows digestion and keeps you feeling full longer. The high water content after boiling adds volume to your meal without adding calories, which is one reason boiled or steamed sweet potatoes work well for people managing their weight.
The carbohydrate content (18 grams per 100g cooked) is almost entirely complex starch rather than sugar, despite the name. You’ll notice sweetness when you eat one, but a plain sweet potato has less sugar per serving than a banana or an apple. Baking does bring out more sweetness by converting some starch to sugar through heat, but it doesn’t change the total calorie count.
Keeping Sweet Potatoes Low-Calorie
The sweet potato itself is not the calorie problem. It’s what goes on top. A tablespoon of butter adds about 100 calories, nearly doubling a small sweet potato. A holiday casserole with marshmallows and brown sugar can easily push a serving past 300 or 400 calories. If you’re eating sweet potatoes for their nutritional profile, the simplest preparations deliver the best return: baked whole, steamed, or roasted with a light coating of oil and salt.