The time it takes to cook a whole chicken depends mainly on its weight and the oven temperature used. Here are general guidelines:

• For a chicken around 1 kg (2.2 lbs) or smaller, roast at 200°C (180°C fan) or gas mark 6 for about 1 hour

• Larger chickens, around 1.5 to 2.5 kg (3.3 to 5.5 lbs), typically take between 1 hour 15 minutes to 1 hour 40 minutes at similar temperatures

• A common rule is to roast for about 45 minutes per kilogram plus an additional 20 minutes at 200°C (180°C fan)

• At 350°F (175°C), a 3-pound (1.36 kg) chicken takes a little over 1 hour to cook fully

• Some methods start roasting at a high temperature (e.g., 425°F or 220°C) for 10-15 minutes to crisp the skin, then reduce to 350°F (175°C) and cook for about 20 minutes per pound (about 45 minutes per kg)

• The chicken is done when the internal temperature reaches 165°F (74°C) in the thickest part of the thigh, or when juices run clear and meat is opaque

In summary, for an average whole chicken weighing between 1 and 2.5 kg, roasting at around 180-200°C usually takes between 1 to 1.5 hours, with adjustments for size and oven type. Always confirm doneness with a meat thermometer or by checking clear juices to ensure safe cooking