Potato Cooking Time Calculator

Potato cooking time depends on three things: the cooking method, the size of the potato or of the pieces, and the variety. Get those right and you stop producing potatoes that are raw in the middle and collapsing on the outside.

Potato varieties and their best uses:

• Russet (floury): High starch, low moisture. Best for baking, mashing, and frying. Breaks down when boiled, great for mashed potato but falls apart in salads.
• Yukon Gold / all-purpose: Medium starch. Versatile, works well for boiling, roasting, or mashing. Holds shape better than Russet.
• New potatoes / baby potatoes: Low starch, waxy. Hold their shape perfectly, ideal for salads, boiling, and roasting whole.
• Red potatoes: Waxy, low starch. Best for boiling and potato salads.
• Fingerlings: Thin-skinned, waxy. Great roasted whole or halved.

Size means piece size, not potato size

This is the part that trips people up. For boiling whole, baking and microwaving, the potato is the piece and its size is what matters. For roasting and steaming you have already cut it up, and a large potato in 1-inch chunks cooks like small pieces, not like a large potato. Choose the size that describes what is actually going in the pan.

Cooking method guide:

Boiling (whole): Small (60 to 100g / 2 to 3.5oz): 15 to 20 minutes Medium (150 to 200g / 5 to 7oz): 25 to 35 minutes Large (250 to 350g / 9 to 12oz): 40 to 50 minutes Start in cold salted water, bring to a boil, then hold a steady simmer. Done when a knife slides in and out with no resistance.

Baking (whole, oven at 200°C / 400°F): Medium: 50 to 65 minutes Large: 65 to 80 minutes Pierce the skin first. Rub with oil and salt for a crisp skin.

Roasting (cut into chunks, 210°C / 425°F), by chunk size: 2.5cm (1 inch) chunks: 25 to 35 minutes 4cm (1.5 inch) chunks: 35 to 45 minutes 5cm (2 inch) chunks: 45 to 55 minutes Parboil 5 minutes and rough up the edges first for the crispiest result.

Steaming, by piece size: 1.5cm (½ inch) cubes: 8 to 12 minutes 2.5cm (1 inch) pieces: 12 to 18 minutes 4cm (1.5 inch) chunks: 18 to 25 minutes

Microwave (whole): Medium potato: 6 to 8 minutes (flip halfway) Large potato: 8 to 11 minutes (flip halfway) Pierce 10 times with a fork first, or it will burst.

Doneness test: a thin knife or skewer at the thickest point should slide in and out with no resistance. If you want a number, potato starch finishes gelatinizing around 98°C (208°F) internally, which is why a boiled potato is done just short of the boiling point of the water it is sitting in.

Altitude

Boiling and steaming both slow down at altitude, because water boils cooler. Above about 1,000 m (3,300 ft) add roughly 5 to 10% per 1,000 m to the boiled and steamed times below, the same correction the egg timing page applies.
Baking, roasting and microwaving are unaffected: an oven holds whatever temperature you set, and a microwave heats the water inside the potato directly rather than transferring heat through boiling water.