A medium sweet potato (about 5 inches long, 130g) contains roughly 112 calories. That makes it one of the more calorie-friendly starchy foods you can put on your plate, landing well below a similar serving of white rice or pasta. The exact number shifts depending on the size of your potato and how you cook it.
Calories by Size
Sweet potatoes vary quite a bit at the grocery store, so size matters when you’re counting calories. A small sweet potato (around 60g) comes in at roughly 54 calories. A medium one (130g) sits around 112 calories. A large sweet potato (180g) provides about 162 calories. Most of those calories come from carbohydrates, specifically natural sugars and starch, with very little fat.
How Cooking Changes the Count
The way you prepare a sweet potato affects its calorie density more than most people realize. Baking concentrates the sugars and evaporates water, which raises the calorie count per bite. One cup of baked sweet potato (200g) contains about 180 calories. One cup of boiled, mashed sweet potato (328g) contains around 249 calories, but that’s a much larger portion by weight. Gram for gram, boiled sweet potato is slightly lower in calories because it retains more water.
Roasting at high heat has a similar concentrating effect to baking. If you’re adding oil or butter before roasting, that changes the math significantly: a single tablespoon of olive oil adds 120 calories on top of whatever the potato itself contributes.
What Else You’re Getting
Sweet potatoes earn their reputation as a nutrient-dense food. A medium potato (130g) delivers 26 grams of carbohydrates, 4 grams of dietary fiber, and 2 grams of protein. Subtract the fiber and you get about 22 grams of net carbs, which is the number that matters most if you’re tracking carb intake for blood sugar management or a low-carb diet.
Sweet potatoes are also packed with beta-carotene, the pigment responsible for their orange color, which your body converts into vitamin A. A single medium sweet potato provides several times the daily recommended amount. You’ll also get meaningful amounts of potassium, vitamin C, and manganese.
Glycemic Index: Lower Than You’d Expect
Despite being a starchy food, sweet potatoes have a moderate glycemic index. Steamed sweet potato scores around 63, baked comes in at 64, and microwaved at 66. All three fall into the medium GI range, meaning they raise blood sugar more gradually than white bread, white potatoes, or white rice. The fiber content plays a big role in slowing that sugar release.
Interestingly, the cooking method barely changes the glycemic impact. The difference between steaming and microwaving is only a few points, so you can choose your preferred method without worrying much about blood sugar effects.
Eat the Skin
Most of the fiber in a sweet potato is concentrated in the skin. Peeling it before eating removes a significant portion of that 4 grams of fiber, which means you lose some of the blood sugar-stabilizing and digestive benefits. The skin is completely edible when cooked and adds a pleasant texture, especially when baked or roasted until slightly crispy. Give it a good scrub before cooking and leave it on.
How Sweet Potatoes Compare
- White potato (medium, 150g): about 130 calories with slightly less fiber and no beta-carotene
- Brown rice (1 cup cooked): about 215 calories with similar fiber but more protein
- Quinoa (1 cup cooked): about 222 calories with double the protein
- Banana (medium): about 105 calories, comparable but with less fiber and fewer micronutrients
Sweet potatoes sit at the lower end of the calorie spectrum among common starches while delivering more vitamins and fiber per calorie than most alternatives. Whether you’re baking one as a side dish or mashing it into a bowl, you’re getting a solid nutritional return for a modest calorie investment.