Potato size matters more than one exact clock time. As a household guide, baby potatoes or cubes around 1 inch across often need about 12 minutes after the water reaches a gentle boil; small potatoes or larger cubes about 15 minutes; and medium potatoes around 20 minutes.
These numbers are starting points. Variety, starting temperature, altitude, and actual piece size all change timing. The final test should be texture: a thin knife should enter with the amount of resistance appropriate for the dish you are making.
Start in cold water so the center and outside heat more evenly
Drop a large potato directly into boiling water and the outside begins softening much earlier than the center. The result can be broken, waterlogged edges around a still-firm middle.
Potatoes USA recommends covering potatoes with cold water and bringing them up gradually. Once the water reaches a boil, reduce heat to a steady simmer rather than letting the potatoes knock around in a violent boil.
Small cubes: about 12 minutes
Pieces around one inch, or very small baby potatoes, commonly take about 12 minutes once the water is gently boiling. This size works well for salads, later pan-crisping, or a quick side dish.
If the potatoes need to hold their shape for salad, begin checking slightly early. The center should be cooked through without the piece becoming so soft that it breaks apart while being dressed.
Two-inch pieces or small potatoes: around 15 minutes
As pieces approach two inches, heat has farther to travel before the center becomes tender. Around 15 minutes is a useful reference, although floury varieties can soften sooner.
For potatoes that will be roasted or sautéed after boiling, stop when the center has only just become tender because a second cooking stage is still coming.
Medium whole potatoes: roughly 20 minutes or longer
Potatoes USA places medium potatoes around 20 minutes, while larger pieces destined for mashed potatoes can take closer to 30 minutes or more depending on size and variety. Very large whole potatoes cook less evenly and are usually better cut.
If a potato is much larger than roughly 3 inches across, halving or quartering shortens the distance to the center and reduces the chance of a waterlogged exterior.
For mashed potatoes, cook more tender than for salad
A potato for mash should offer very little resistance to a knife or fork. A firm central core creates hard lumps. On the other hand, cooking far beyond tenderness can load the potato with unnecessary water and make the finished mash heavier.
Once tender, drain thoroughly and let steam escape for a minute or two before mashing. This brief surface drying is particularly useful with floury potatoes.
For salad, stop exactly at tender
Waxy or firm-fleshed potatoes hold together more easily. Test with a knife tip: it should pass through without finding a raw core, but the piece should not crumble when lifted.
Uniform pieces finish at nearly the same time. Mixing tiny cubes and large chunks forces you to choose between overcooking one group and undercooking another.
Altitude and pot load change timing
At higher altitude, water boils at a lower temperature and potatoes may need longer. A heavily loaded pot also takes longer to recover heat.
The practical rule: start with cold water, cut pieces evenly, and count from a gentle boil. Think about 12 minutes for baby potatoes or small cubes, 15 for small pieces, and 20 or more for medium potatoes. Stop when texture suits the dish, not simply when the timer rings.
These quantities are planning references rather than mandatory nutrition targets. Appetite, age, the rest of the meal, and the role of the food in the recipe all change how much is needed. For larger groups, weighing the dry ingredient and noting the actual yield of your brand or variety greatly reduces waste.
These quantities are planning references rather than mandatory nutrition targets. Appetite, age, the rest of the meal, and the role of the food in the recipe all change how much is needed. For larger groups, weighing the dry ingredient and noting the actual yield of your brand or variety greatly reduces waste.
Frequently asked questions
How long do potatoes take to boil?
As a guide, about 12 minutes for baby potatoes or small cubes, 15 for small pieces, and around 20 or more for medium potatoes.
Should potatoes start in cold or boiling water?
Starting in cold water and bringing them gradually to a gentle boil promotes more even cooking.
How do I know potatoes are ready for mash?
A knife or fork should enter the center with very little resistance.
Sources
- Potatoes USA — How to Cook Potatoes Perfectly — Practical boiling times by potato size: baby or 1-inch diced about 12 minutes, small or 2-inch diced about 15, medium about 20.
- Penn State Extension — Potatoes in the Garden and the Kitchen — Cooking example using potato pieces simmered from cold water until fork tender in roughly 15–20 minutes.
- Potatoes USA — Do you boil the water before adding potatoes? — Recommends starting potatoes in cold water and bringing them up to a gentle simmer for more even cooking.