Advanced options
Maris Piper or King Edward. The three commandments: parboil 8-10 mins until the edges just start to break, shake HARD in the colander (the roughed-up surface IS the crunch), and drop into fat that's been preheating in the tray until shimmering. Space matters: crowded potatoes steam. One layer, room between, turned once.
What The Roast Potato Calculator Works Out
- Potatoes (unpeeled weight): people multiplied by the grams per head you pick. 250g of unpeeled potato per person is Sunday's most reliable constant; 200g suits a restrained table and 350g the household where the roasties are the point. Floury Maris Pipers and King Edwards fluff and crisp where waxy salad potatoes merely tan.
- Fat: 50g per kilo of potatoes, enough to coat the tray and sizzle. Goose fat, dripping and oil all crisp equally well; flavour, not physics, separates them, and oil serves vegetarians identically.
- Method: parboil 8-10 minutes, shake hard to rough the surface, drop into preheated fat and roast at 200C (180C fan) for 55-65 minutes, turning once. Salt at the end, because early salt draws moisture against the crisp.
- Cooking in (advanced): switches the method and timings for a fan oven (about 5 minutes quicker, browns faster) or an air fryer (25-30 minutes a batch at roughly 1kg per batch, so big tables need several batches kept warm).
- Serving time and timeline (advanced): counts backwards from the time you want to eat to give a peel, parboil, fat-preheat and oven-in time, plus the moment to turn them. Peeling is estimated at 8 minutes per kilo; do it the day before and hold the potatoes in cold water to spread the labour.
- Extra portions for leftovers (advanced): adds portions for bubble and squeak or a fried-potato breakfast. Fully roasted then flash-reheated potatoes survive better than tradition admits, which is how caterers do it.
- Peeled weight (advanced): about 80% of the unpeeled weight once the skins are off, useful if your recipe or pan capacity is quoted peeled.
- Bags to buy and potato cost (advanced): rounds the weight up to whole bags of the size you buy and prices them at your per-kilo price (own-brand bags are typically GBP 0.70 to GBP 1.00 a kilo). The sub-line gives the cost per portion and a rough figure for the fat.