Chef’s Roast Calculator
Pick the joint, put in the weight, and this gives you the oven setting, roughly how long it needs, the core temperature to pull it at, how long to rest it — and, if you tell it when you want to eat, what time it has to go in.
0.3 to 15 kg
Times are estimates and ovens vary. Chicken, turkey and pork must reach the core temperature shown. Rare and pink only apply to whole joints of beef and lamb, never to rolled, stuffed or minced meat.
The one tool that makes this work
Every number on this page is a core temperature, and you cannot see a core temperature. A fast probe thermometer is the difference between a guess and a result: the Thermapen ONE reads in about a second and holds 0.3°C accuracy across normal cooking temperatures.
See the Thermapen ONE on Amazon
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Why I go by temperature, not the clock
Two ovens set to the same number are rarely the same oven. Door seals leak, fans move air differently, a cold joint straight from the fridge behaves nothing like one that has stood out for an hour, and a wide flat joint cooks faster than a tall round one of the same weight.
That is why the time on this page is an estimate and the temperature is not. Use the clock to plan your day and the thermometer to decide when the meat is done.
Carry-over cooking: take it out early
Meat keeps cooking after it leaves the oven. The outside is hotter than the middle, and that heat travels inwards while the joint rests, lifting the core by roughly 3 to 5°C on a normal roast.
So the pull temperature above is deliberately lower than the temperature you want to eat. Take it out, rest it, and let physics finish the job. More on that in resting meat: why five minutes matters.
Quick reference
Fan oven, typical weights. Same formulas as the calculator.
| Joint | Weight | Oven | Roughly | Take out at | Rest |
|---|---|---|---|---|---|
| Whole chicken | 1.8 kg | 180°C | 1 h 30 min | 75°C | 15–20 min |
| Turkey crown | 2.5 kg | 170°C | 1 h 50 min | 75°C | 20–30 min |
| Whole turkey | 5 kg | 170°C | 3 h 10 min | 75°C | 30–60 min |
| Beef joint, medium-rare | 1.5 kg | 200°C for 20 min, then 160°C | 1 h | 52°C → 56°C | 20–30 min |
| Pork joint (loin/leg) | 1.5 kg | 200°C for 25 min, then 160°C | 1 h 20 min | 67°C → 70°C | 20–30 min |
| Leg of lamb, pink | 2 kg | 200°C for 20 min, then 160°C | 1 h 20 min | 55°C → 59°C | 15–20 min |
Before it goes in
Three things decide more than the oven setting does: how it is seasoned, how dry the surface is, and whether the gravy is already made.