20 minutes per 500g, plus 20 minutes at 190°C (fan 170°C / 374°F, gas mark 5).
For a whole roast chicken, the reliable rule is 20 minutes per 500g plus an extra 20 minutes at 190°C (fan 180°C). Weigh the bird (with any stuffing) and do the maths — then always confirm it’s done with the checks below rather than the clock alone.
Worked examples
A typical 1.5kg supermarket chicken takes about 1 hour 20 minutes; a larger 2kg bird around 1 hour 40. Ovens vary, so start checking 10 minutes before the calculated time.
Always check it’s cooked
The safe test is simple: pierce the thickest part of the thigh — the juices should run clear, not pink — and, ideally, a thermometer should read 75°C. Rest the bird for at least 15 minutes so the juices settle and it carves neatly.
Method
- Take the chicken out of the fridge 30 minutes before cooking and heat the oven to 190°C (fan 180°C).
- Weigh the bird and calculate: 20 minutes per 500g, plus an extra 20 minutes.
- Roast breast-up, basting once or twice if you like.
- Rest, loosely covered, for at least 15 minutes before carving.
How to tell it's cooked
- Juices run clear (not pink) when the thickest part of the thigh is pierced
- 75°C in the thickest part of the thigh, away from the bone
- The leg feels loose and wobbles easily in its socket
Times by size
| Size / type | Time |
|---|---|
| 1kg | about 1 hour |
| 1.5kg | about 1 hr 20 min |
| 2kg | about 1 hr 40 min |
| 2.5kg | about 2 hours |
Food safety: Chicken must be cooked right through — 75°C in the thickest part, with clear juices and no pink meat. Don't wash raw chicken (it splashes bacteria); wash hands and surfaces after handling. Rest before carving, and cool leftovers quickly to refrigerate.