Boiled Potato Cooking Time Calculator
Choose how the potatoes are prepared for the boiling time and whether to start them cold.
Used to work out how many potatoes to buy. It does not change the cooking time.
Answer
15–18 minutes
The details
Next step
Worth knowing
- Start peeled potatoes in cold salted water and bring them up to the boil. Dropping them into boiling water cooks the outsides before the middles are done.
- Time from the moment the water is boiling again, not from when the potatoes went in.
- Test with the tip of a knife in the largest piece. It should slide in with no resistance.
Source: Standard UK packet and cookery-school timings for boiled and steamed staples · Reviewed 2026-09-10 · Guidance version 1.0.0
Reference and detail
Start big potatoes in cold water
Cold water lets the outside and the middle heat at a similar rate. Dropping a large potato into boiling water gives you a collapsing outside and a raw centre.
Cut them the same size
Even chunks cook evenly. A tray of mixed sizes means some are falling apart while others are still firm.
Dry them for better mash
Drain, then leave them in the hot dry pan for a minute so the steam escapes. Wet potatoes make wet mash.
Questions and answers
Questions about boiling potatoes
Should potatoes go into cold or already-boiling water?
Start large or whole potatoes in cold water so the heat reaches the centre at roughly the same rate as the outside cooks. Dropping them straight into boiling water risks a collapsing outside and a raw middle.
How do I stop potatoes falling apart before they are fully soft?
Cut them into even-sized chunks so they cook at the same rate, and keep the water at a gentle simmer rather than a hard rolling boil, which knocks the pieces against each other and the sides of the pan.
Should new potatoes be boiled differently from old ones?
New potatoes are thin-skinned and cook faster, so start them in already-boiling, well-salted water rather than cold water, cold-starting them tends to overcook the outside before the middle is done.
Why is my mash wet even though the potatoes seemed cooked?
Leftover water clinging to the potatoes after draining goes straight into the mash. Drain them well, then leave them in the hot, dry pan for a minute so the surface moisture steams off before you mash.
Safety guidance reviewed against Food Standards Agency sources on 11 September 2026. How we calculate cooking times and safety guidance.