Roasting Time Calculator

Time per kilogram is how recipes are written and it is a guide rather than a rule. A joint's thickness matters more than its mass — a long thin piece cooks faster than a compact one of the same weight — and a joint straight from the fridge takes noticeably longer than one that has stood at room temperature for an hour. Oven dials are also frequently 10 to 20°C out.

Which is why the internal temperature is given the same prominence as the time. It is the only thing that actually determines whether meat is cooked, and a thermometer in the thickest part, away from bone, settles in seconds what a timer only estimates. If you roast more than a few times a year it is the single most useful thing you can buy for the job.

Resting is not optional and it is not idle time. Muscle fibres contract during cooking and squeeze juices toward the centre; resting lets them relax and redistribute. Carve straight from the oven and a good deal of what you cooked ends up on the board. Twenty minutes for a joint, fifteen for a chicken, half an hour for a turkey — and the internal temperature continues to rise a few degrees during it, which is worth allowing for.

Poultry and pork have no doneness setting here because there is only one safe answer. Chicken, turkey and duck want 75°C throughout; pork wants 71°C. Beef and lamb are the ones where preference genuinely applies.

If your oven has a fan, use the lower temperature shown. A fan oven at the conventional figure runs hot, browning the outside well before the middle is done.