How many calories in a potato? Boiled, baked, fries

A potato has no label, yet it is one of the easiest foods to count, as long as you eat it plain. According to Ciqual, the French reference food table published by the food safety agency ANSES, 100 g of raw peeled potato contains 80 kcal, and the same amount boiled provides 81 kcal. Boiling adds nothing: the potato keeps roughly its weight, so it keeps its calories.

Almost all of those calories come from starch. Per 100 g of boiled potato, Ciqual lists 16.8 g of carbohydrate, of which less than 1 g is sugar, 1.8 g of protein, 1.8 g of fibre and only 0.3 g of fat. Three quarters of a potato is water (78 %), which explains its low calorie density.

The other big food tables land in the same range. The USDA lists 77 kcal per 100 g of raw potato with the skin and 86 to 87 kcal once boiled; Norway’s Matvaretabellen ranges from 63 kcal for a boiled new potato to 94 kcal for a boiled storage potato. The gap mostly comes down to water: new and early potatoes are more watery, so they have slightly fewer calories than potatoes stored over the winter.

The question comes up all the time: does a baked potato have more calories than a boiled one? On paper, yes: 91 kcal per 100 g against 81 according to Ciqual. In reality, the potato has gained nothing. In the oven it loses water (its water content drops from 79 % to 75 %), it gets denser, so 100 g of baked potato simply holds a little more dry matter.

The microwave takes this further: the USDA measures 105 kcal per 100 g of potato microwaved in its skin, because it dries out more. Steaming, on the other hand, stays close to boiling: 76 kcal per 100 g according to Ciqual, for vacuum-packed steamed potatoes.

The practical consequence: a 150 g raw potato provides about 120 kcal, whether you boil it, steam it or bake it without fat. Only the “per 100 g” figure moves, because the weight changes.

On the plate, potatoes are rarely served plain. Mash with butter, creamy gratin, sautéed potatoes, fries or crisps: each time, the potato soaks up fat, and that is where the calories climb. The reason is simple: 1 g of fat provides 9 kcal, more than twice as much as a gram of carbohydrate (4 kcal), according to the conversion factors of the EU food labelling regulation.

Two effects add up. The potato loses its water (crisps contain only 1.4 %, against 78 % for a boiled potato) and it fills up with fat: 0.3 g per 100 g boiled, 11.9 g for deep-fried fries, 33 g for crisps. The result: 100 g of crisps contain more than six and a half times the calories of 100 g of boiled potatoes.

Fries and crisps raise a second problem: nobody eats them off a scale. Fast-food servings give a benchmark. The USDA weighs a small serving of fries at 71 g, a medium at 117 g and a large at 154 g; the Norwegian table uses 135 g for a portion of takeaway fries. At about 312 kcal per 100 g, a medium serving already tops 360 kcal, more than four 100 g boiled potatoes.

Frozen “oven” fries are lighter (213 kcal per 100 g once cooked), but they are not fat-free: they are pre-fried at the factory and already contain almost 5 g of fat per 100 g before they even go into the oven, according to Ciqual.

What about the air fryer? A study published in 2015 in the Journal of Food Science compared it with a deep fryer on fries prepared under the same conditions: the air-fried fries contained substantially less fat, but needed 21 minutes of cooking against 9, with a different texture and taste. For homemade fries, the maths is simple: the calories of the potato, plus the oil you put in the basket.

“A medium potato” does not mean much: there is no official weight, and the food tables do not agree. The Norwegian table counts 30 g for a small potato, 55 g for a medium one and 100 g for a large one, with a side portion of 170 g. The USDA, used to big American potatoes, counts 170 g for a small one, 213 g for a medium one and 369 g for a large one, raw.

So the only reliable method is a kitchen scale. Weigh one of your potatoes once and you will know for good whether you usually buy 60 g or 200 g ones. Because a boiled potato keeps roughly its weight, you can weigh it raw or cooked with the same value; for baked potatoes, use the “baked” value if you weigh after cooking. For pasta and rice, on the other hand, the gap between raw and cooked is huge, as our guide to pasta and rice calories, raw or cooked explains.

One last detail, peeling: Matvaretabellen puts the edible part of a raw potato at 82 %. If you weigh before peeling, take off about a fifth of the weight.

Sweet potato has a “healthy” reputation, but it is not especially light: raw, it contains 81 kcal per 100 g according to Ciqual, against 80 for potato, and cooked, 79 kcal against 81 for boiled potato. Baked, the gap changes direction depending on the table: 90 kcal for sweet potato and 93 for potato according to the USDA, 111 against 106 according to Matvaretabellen. On calories, it is a draw.

The differences lie elsewhere. Sweet potato has more fibre (3 g against 2.2 g per 100 g raw) and much more sugar (4.2 g against 0.8 g), hence its sweet taste. Above all, it is very rich in beta-carotene, the pigment that turns its flesh orange and that the body converts into vitamin A: 8,510 µg per 100 g according to Ciqual, while potato contains practically none.

Potatoes carry a reputation as a fattening starch. The numbers suggest the opposite, as long as they stay plain. Weight for weight, they are even lighter than other cooked starches: in the Ciqual table, 100 g of boiled potato contains 81 kcal, against 155 kcal for cooked white rice and 167 kcal for cooked pasta, about half as much.

They are also very filling. In an Australian study published in 1995, volunteers ate 240 kcal portions of 38 common foods, then rated how full they felt for two hours. Boiled potatoes got the highest satiety score: 323 %, more than three times white bread (100 %) and seven times the croissant. The most filling foods were those that provided the most water, fibre and protein for their calories; the fattiest were the least filling. For 240 kcal, you eat about 300 g of boiled potatoes, but only 45 g of crisps.

The flip side is the glycaemic index, which is often high. A Canadian study from 2005 measured an index of 89 for boiled red potatoes eaten hot, but only 56 for the same potatoes eaten cold. The authors advise cooking potatoes in advance and eating them cold or reheated to limit the rise in blood sugar. Our guide to the glycaemic index also explains how vegetables, protein and dressing change the picture.

A plain potato provides about 80 kcal per 100 g, whether raw, boiled or steamed, and a little more when baked (91 kcal) because it loses water. Per potato, count 8 kcal for every 10 g: about 45 kcal for 55 g, 80 kcal for 100 g, 170 kcal for 213 g. Butter, oil, cream and frying are what change the total: 213 to 312 kcal per 100 g of fries, 532 kcal for crisps. Sweet potato has no fewer calories, but it brings more fibre and beta-carotene. Filling and low in calorie density, a plain potato fits perfectly into a calorie deficit, as long as you keep an eye on what comes with it.