How Can You Tell Starchy Potatoes from Waxy Potatoes?

The difference comes down to the balance of starch and water. Starchy potatoes have more starch and less water; as they cook, the starch granules swell and separate, and the potato breaks apart. That is exactly what you want for mashed potatoes, which turn out fluffy and light. Waxy potatoes have less starch and more water; their granules stay together, so the slices hold their shape after cooking. Even the same field and season can yield different results; a potato’s starch content decreases somewhat the longer it is stored.

That is why each type has its best uses. Mashed potatoes, baked potatoes with crisp skin, and crispy fries call for starchy potatoes. Boiling, potato salad, stews, sautés, and baked slices cooked with sauce call for waxy potatoes. The wrong choice is immediately noticeable: mashed potatoes made with waxy potatoes turn out sticky and rubbery, while potato salad made with starchy potatoes becomes a smashed pile on the plate. Both types can be used in soup: starchy potatoes thicken the soup on their own, while waxy potatoes remain in pieces.

Start by looking at the skin. Starchy potatoes usually have duller, thicker skins with a netlike pattern and feel rough to the touch. Waxy potatoes have thin, smooth, shiny skins that can often be peeled by hand. Size is another clue: waxy varieties are often smaller and oval. These signs are not definitive, but together they are usually a reliable guide. Potatoes with green skin, sprouts, or soft spots should be sorted out regardless of type.

The most reliable clue comes from a cut surface. When you cut a potato in half, a starchy type leaves a whitish, dry starch film on the knife; the two halves stick slightly when rubbed together. A waxy potato has a wetter, shinier cut surface and leaves no mark on the knife. If the same potato feels light in your hand, it has more starch; if it feels heavy and dense, it contains more water. The saltwater float test is also used traditionally, but its result is not definitive because the salt concentration is not standardized.

In Türkiye, potatoes are often sold as yellow or red rather than by variety, so asking the produce clerk is the most practical option. If they do not know, buy a small batch, test it, and note the result. You can also work with what you have: to make mashed potatoes with waxy potatoes, use plenty of butter and mash them as little as possible, pressing the masher down without twisting it. To make potato salad with starchy potatoes, boil them whole with their skins on, then chop them after they have cooled.