The size of the turkey you'll need for Christmas depends on how many people you plan to serve and whether you want leftovers. A general rule of thumb is to estimate about 450g to 680g of turkey per person. Here are some guidelines to help you choose the right size turkey:
Small turkey (5kg): Suitable for serving 10-12 people. This size is ideal if you have a small gathering and don't want too many leftovers.
Medium turkey (7kg): Suitable for serving 14-16 people. This size should be sufficient for a moderate-sized group and may provide some leftovers.
Large turkey (9kg): Suitable for serving 18-20 people. If you're hosting a larger gathering or want plenty of leftovers, a larger turkey is a good choice.
Extra-large turkey (11kg+): Suitable for serving 22-25 or more people. If you have a very large crowd or want lots of leftovers, consider an extra-large turkey.
Keep in mind that these are just rough guidelines, and the actual size you need may vary based on your guests' appetites and whether you want extra turkey for sandwiches and leftovers. Additionally, if you're serving a variety of other dishes, you may be able to get away with a slightly smaller turkey.
It's a good idea to plan ahead and order your turkey in advance, especially if you're looking for a specific size or type (e.g. free-range). Also, be sure to check the cooking instructions for the turkey you choose, as cooking times and temperatures can vary based on the turkey's size.