The amount of space needed in a microwave convection oven to roast a whole chicken evenly can vary depending on the size of the chicken and the specific model of the oven. Generally, you'll want to choose a microwave convection oven that can accommodate the size of the chicken you plan to roast.
A typical whole chicken for roasting can weigh anywhere from 1.5 kg to 2.5 kg (3.3 to 5.5 pounds). To ensure even cooking, it's important to have enough space around the chicken for the hot air to circulate and cook it thoroughly.
As a rough estimate, you should look for a microwave convection oven with a capacity of at least 30 liters or more. This will give you enough space to comfortably roast a whole chicken without crowding the oven, allowing for proper air circulation and even cooking.
Remember that microwave convection ovens come in various sizes, so it's essential to check the specifications of the particular model you are considering to see if it can accommodate the size of chicken you intend to roast. Additionally, follow the manufacturer's guidelines for roasting chicken or any other food item to achieve the best results.