How many calories are in a sweet potato?
A medium sweet potato baked in its skin — about 150 g (5 oz) — is roughly 135 kcal. Per 100 g raw it comes to about 85 kcal, which is marginally higher than a white potato, not lower. If you swapped one for the other to save calories, you did not.
Per portion
| Portion | Calories | Protein | Carbs | Fat |
|---|---|---|---|---|
| One medium, baked in skin (150 g / 5 oz) | ~135 kcal | 3 g | 31 g | 0 g |
| 100 g (3.5 oz) raw | ~85 kcal | 1.5 g | 20 g | 0 g |
| 100 g boiled, peeled | ~75 kcal | 1.5 g | 17 g | 0 g |
| 100 g baked in skin | ~90 kcal | 2 g | 21 g | 0 g |
| One large, baked (250 g / 9 oz) | ~225 kcal | 4 g | 52 g | 0.5 g |
| 150 g roasted in one tablespoon of oil | ~255 kcal | 3 g | 31 g | 13 g |
| 150 g sweet potato fries | 280–400 kcal | 3 g | 40 g | 14–25 g |
What changes the number
Boiling lowers it, baking raises it. Boiled sweet potato lands near 75 kcal per 100 g; baked, around 90. Nothing has been added — water has left, so the remaining grams are denser. Weigh before cooking if you want figures that compare.
Oil, as always, dominates. A tablespoon is about 120 kcal, which nearly doubles a 150 g portion on its own. Sweet potato is cut thin more often than white potato is, and thin cuts have more surface for oil to cling to, so “sweet potato fries” are usually the most calorie-dense thing on the plate despite the halo. Deep-fried, the same weight can reach three times the baked figure.
What tradition adds. Candied sweet potato, marshmallow toppings, maple glaze and brown sugar are not marginal: two tablespoons of maple syrup is about 100 kcal, and a glaze can add more energy than the vegetable carries.
Size. “Medium” covers 130–200 g (4.5–7 oz) in practice, so one sweet potato honestly spans 115–180 kcal baked.
Where it fits in a deficit
Low calorie density, high water, decent fibre, very filling for the energy — all the high-volume virtues that make the white potato useful apply here too, and the two are close enough that you should simply pick the one you would rather eat. See the white potato figures if you want them side by side.
Protein is low, around 1.5 g per 100 g, so this is a carbohydrate base rather than a meal. It wants something protein-dense next to it, as most starches do when you are building meals to a calorie target.
Where sweet potato genuinely differs is after the calorie column. Orange varieties are an outstanding source of beta-carotene, which the body converts to vitamin A, and the glycaemic response to boiled sweet potato is lower than to boiled or mashed white potato. Both are real advantages. Neither is a calorie advantage, and a calorie deficit is still decided by the total.
One popular swap worth checking against the table: sweet potato slices in place of toast. A 30 g round is about 25 kcal against roughly 90 for a medium slice of bread — a saving, but only because the portion shrank.
Variety and storage change the sweetness, not the energy
Sweet potatoes are cured after harvest and go on converting starch to sugar in storage for weeks. A tuber kept two months tastes noticeably sweeter than one just lifted, while its total carbohydrate — and so its calories — has barely moved. Sweetness is a poor guide to energy here.
Flesh colour is a better guide to nutrients than to calories. Purple-fleshed and the drier, denser white or cream-fleshed types common in Japanese cooking hold less water, which puts them a little higher per 100 g — perhaps 10–20 kcal — and makes them taste starchier rather than sweeter.
Figures are typical values and vary by variety, size and preparation. General information, not medical advice.