Roasting Time Calculator
How long to roast a joint or bird by weight and how you want it done — with the resting time and the internal temperature that actually decides it.
Roasting guides work in minutes per kilogram plus a fixed allowance, because a joint gains time from both its mass and its surface.
How the roasting time calculator works
Roasting guides work in minutes per kilogram plus a fixed allowance, because a joint gains time from both its mass and its surface. They are starting points, not answers: shape, bone, starting temperature and how honest your oven is all shift the result, sometimes by twenty minutes.
The internal temperature is what matters, and it is the one number worth owning a probe for. Resting is not optional either — the temperature keeps climbing several degrees after it leaves the oven, and the juices redistribute instead of running out onto the board.
Formula: time = minutes per kg × weight + fixed allowance
Worked examples
| Inputs | Roasting time | Note |
|---|---|---|
| A 2 kg chicken | 2 h 0 min | 1 h 50 min at 200°C, rest 14 min |
| A 1.5 kg beef joint, medium | 58 min | 57 min, out at 58°C |
| A 5 kg turkey | 4 h 5 min | 3 h 45 min, rest 30 min |
FAQFrequently asked questions
How long do I roast a chicken?
About 45 minutes per kilogram plus 20 minutes at 200°C — so a 2 kg bird takes roughly 1 hour 50 minutes. Confirm 75°C in the thigh.
What internal temperature should I cook to?
Poultry 75°C throughout. Beef about 52°C rare, 58°C medium, 68°C well. Pork 65–71°C. Lamb similar to beef.
Why rest the meat?
Because the temperature keeps rising a few degrees and the juices redistribute. Carve immediately and they run onto the board instead.
Is this a food-safety guarantee?
No. It is a timing guide — the thermometer is what makes it safe, particularly for poultry and stuffed joints.
Does a fan oven change it?
Set the fan oven about 20°C lower and use the same times, or keep the temperature and check 15–20% earlier.
Where these figures come from
- US FDA — Safe Minimum Internal Temperatures — the internal temperatures the roasting calculator targets
- NIST SP 811 — Guide for the Use of the International System of Units — the exact weight and volume conversions used throughout
- Food Standards Australia New Zealand — food safety and labelling standards
Last checked: September 2026. Baking ratios follow standard baker's percentage practice; roasting guidance follows published safe internal temperatures.