A medium potato (about 150 grams) contains roughly 26 grams of carbohydrates. That number shifts depending on the variety, size, and how you cook it, but it’s a reliable starting point for a typical potato eaten with the skin on. Most of those carbs come from starch, with a small amount of natural sugar and about 2 grams of fiber.
Carbs by Cooking Method
Cooking changes the carb density of potatoes more than most people realize. Boiling a potato in its skin yields about 15.4 grams of carbs per 100 grams. Peel it before boiling and that rises slightly to 17 grams, because you’ve removed the skin’s weight and fiber without removing starch. Baking concentrates carbs further, to about 17.9 grams per 100 grams, since moisture evaporates in the oven.
French fries are in a different category entirely. Deep frying drives off even more water and adds oil, pushing the carb count to around 34 grams per 100 grams, with calories nearly tripling compared to a boiled potato (280 calories versus 66). A typical restaurant serving of fries can easily deliver 50 or more grams of carbs.
How Potatoes Compare to Rice and Sweet Potatoes
Potatoes are often lumped with white rice as a high-carb food, but the comparison is more nuanced than it seems. A medium russet potato (about 138 grams) contains roughly 30 grams of carbs. One hundred grams of cooked white rice contains about 29 grams. Gram for gram, they’re similar, but potatoes carry significantly fewer calories because they hold more water and deliver more potassium, vitamin C, and fiber.
Sweet potatoes and white potatoes are nearly identical in carbohydrate content: 21 grams per 100 grams for both, with skin on. The main nutritional differences between the two show up in vitamin profile and antioxidant content rather than in carb count.
What Happens to Potato Starch in Your Body
Not all potato starch behaves the same way once you eat it. A hot, freshly cooked potato delivers its starch in a form your small intestine breaks down quickly, causing a relatively fast rise in blood sugar. Potatoes generally fall in the medium-to-high range on the glycemic index, with most studies placing boiled potatoes between 59 and 88 and baked potatoes between 48 and 93. That wide range reflects real differences in potato variety, growing conditions, and how the studies were run, but the takeaway is consistent: potatoes raise blood sugar faster than most vegetables and legumes.
Mashed potatoes tend to score highest, often between 74 and 97, because breaking down the cell structure makes the starch more accessible to digestive enzymes. Adding butter, milk, or sour cream can blunt the spike somewhat by slowing digestion, but the effect is modest.
Cooling Potatoes Changes the Starch
Here’s something worth knowing if you’re watching your blood sugar or tracking net carbs: cooling a cooked potato converts some of its starch into resistant starch, a form that passes through your small intestine undigested. This means fewer of those carb grams actually get absorbed as glucose. Chilled potatoes contain more resistant starch than hot ones, and even reheating a previously cooled potato retains some of that benefit. Baked potatoes form more resistant starch than boiled ones when cooled.
Resistant starch functions more like fiber in your gut, feeding beneficial bacteria in the colon rather than spiking blood sugar. So a cold potato salad, nutritionally speaking, delivers a different carb experience than a steaming baked potato, even though the label would show the same number.
Nutrients That Come With Those Carbs
Focusing only on carb content misses what makes potatoes nutritionally interesting. A single medium boiled potato provides about half the daily adult requirement for vitamin C. Potatoes are also one of the richest common food sources of potassium, with roughly 440 to 460 milligrams per 100 grams of raw potato, depending on variety. That’s more than a banana. They also supply meaningful amounts of iron, zinc, and fiber, particularly when eaten with the skin.
The fiber in potato skin slows digestion slightly and adds about 2 grams per medium potato. It’s not a huge amount, but it contributes to the overall nutritional package that separates a whole potato from refined starch sources like white bread or pasta.
Quick Carb Reference by Portion
- Small potato (about 130g, skin on, boiled): 20 grams of carbs, 86 calories
- Medium potato (about 150g, skin on, boiled): 23 grams of carbs, 99 calories
- Large potato (about 200g, skin on, baked): 36 grams of carbs, 170 calories
- Medium serving of french fries (about 115g): 39 grams of carbs, 322 calories
If you’re counting carbs for diabetes management or a low-carb diet, portion size matters more than the cooking method. A small boiled potato with skin fits comfortably into most moderate-carb eating plans, while a large baked potato or a full serving of fries can account for a significant share of a daily carb target.