The standard rule is 1.5 lbs of bone-in turkey per person, accounting for the bone weight and the inevitable seconds. For 8 guests that's a 12 lb bird; for 12 guests, 18 lbs; for 16 guests, 24 lbs (or two smaller turkeys, which actually cook better than one giant one). The tool runs from 4 to 30 guests and handles both stuffed and unstuffed cooking times - 15 minutes per pound at 325°F unstuffed, 20 minutes per pound stuffed.

British hosts running US-style Thanksgiving for friends should size by the same logic, though UK turkeys often come slightly smaller. A typical UK supermarket turkey from Tesco or Sainsbury's covers 6 to 10 people at around 4 to 5kg (around 9 to 11 lbs); for larger parties, butcher-ordered birds or a crown plus thighs combination handles 12 plus more cleanly than a single giant bird that no oven fits.

Sides scale separately from the turkey. The proven per-person allocations: 0.5 lb mashed potatoes, 1/3 cup gravy, 3/4 cup stuffing, 1/4 cup cranberry sauce, two dinner rolls, one small sweet potato. Pumpkin pie comes in at one pie per eight people. For 12 guests that's 6 lbs of potatoes, 4 cups gravy, 9 cups stuffing, 3 cups cranberry sauce, 24 rolls (so 2 packages of 12), 12 sweet potatoes, and 2 pies. Doubling everything for 24 guests is the easy maths but the oven planning gets harder.

Oven scheduling is the silent killer. A 16 lb turkey takes around 4 hours unstuffed, plus a 30-minute rest, blocking the main oven for the entire morning. Casseroles, sides and pies need the oven too, so plan an order: pies first thing or the night before, sweet potatoes early then held warm, stuffing in the oven once the turkey rests. Many hosts cook the turkey on a barbecue or smoker to free up oven space - especially in the UK where ovens are smaller than US ranges. Tip-calculate the night's restaurant alternative with the [US Tip Calculator](/us-tip-calculator) if cooking falls through.