How this calculator works
A whole turkey is about half bone, so the usual rule is 450 to 675 g of turkey per person, and more for leftovers. Children count as half. The Food Standards Agency says to allow 10 to 12 hours a kilo for thawing in the fridge. A common cooking guide is 20 minutes a kilo plus 70 minutes for a bird under 4 kg, or plus 90 minutes for a bigger one, at 180°C (160°C fan).
Worked example: 8 adults and 2 children at 675 g each is 9 servings, so a 6.5 kg turkey. It needs 4 days to thaw in the fridge (78 hours), then 3 h 40 min in the oven and 30 to 60 minutes to rest.
Turkey sizes, thawing and cooking
Fridge thawing at 12 hours a kilo, cooking at 180°C (160°C fan).
| Turkey | Serves (675 g each) | Thaw in the fridge | Cooking time |
|---|---|---|---|
| 3.5 kg | 5 | 2 days | 2 h 20 min |
| 4.5 kg | 6 | 3 days | 3 h |
| 5.5 kg | 8 | 3 days | 3 h 20 min |
| 6.5 kg | 9 | 4 days | 3 h 40 min |
| 7.5 kg | 11 | 4 days | 4 h |
| 9 kg | 13 | 5 days | 4 h 30 min |
Tips before you buy
- Order your turkey early, and decide between fresh and frozen. A frozen one needs days in the fridge to thaw.
- A rule of thumb is 450 to 675 g per person, because a whole turkey is about half bone. Buy more for leftovers and cold cuts on Boxing Day.
- Take the turkey out of the fridge about an hour before cooking, then start in a hot oven and cover with foil for most of the time.
- Use a probe thermometer: 70°C in the thickest part of the thigh, and the juices running clear.
- Rest it well. A turkey needs 30 to 60 minutes under foil to relax, which frees the oven for the roast potatoes.
Tools & materials for this project
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Frequently asked questions
What size turkey do I need for 10 people at Christmas?
About 7 kg at 675 g a head, or 6.5 kg for 8 adults and 2 children. Buy more if you want leftovers for Boxing Day.
How long does it take to thaw a turkey?
Allow 10 to 12 hours per kilo in the fridge. A 6.5 kg turkey needs about 78 hours, or 4 days. Never thaw it at room temperature.
How long do I cook a turkey?
At 180°C (160°C fan) allow 20 minutes a kilo plus 70 minutes for a bird under 4 kg, or plus 90 minutes if it is bigger. A 6.5 kg turkey takes 3 h 40 min. Check with a probe: 70°C in the thickest part of the thigh.
How long should a turkey rest?
Between 30 and 60 minutes under foil. That keeps it juicy and frees the oven for the roast potatoes.
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Estimates only. Results assume standard materials and simple shapes. Supplier products vary, and the final call on quantity, structure and safety is yours. Check your local code and your supplier's guidance before ordering.