How do I calculate roasting time per kilogram?

The general formula varies by meat: Beef (rare) is 15 minutes per 500g plus 15 minutes extra, medium is 20 minutes per 500g plus 20 minutes, and well done is 25 minutes per 500g plus 25 minutes. Lamb follows a similar pattern but slightly longer. Pork is always cooked thoroughly at 30 minutes per 500g plus 30 minutes. Chicken is 20 minutes per 500g plus 20 minutes. All timings assume a fan oven at 180°C.

Should I use fan or conventional oven temperatures?

Fan ovens circulate hot air, cooking meat more evenly and about 20 degrees C lower than conventional ovens. This calculator provides both temperatures. If your oven has a fan setting, use it for more consistent results. The timings given are based on fan oven temperatures. If using conventional, use the higher temperature shown.

How important is resting meat after roasting?

Resting is essential. When meat cooks, the heat forces juices towards the centre. Resting allows these juices to redistribute throughout the joint, resulting in moister, more tender meat. A general rule is 1 minute per 100g, with a minimum of 10 minutes and maximum of 30 minutes. Tent the meat loosely with foil during resting — do not wrap tightly or the crust will go soggy.

How do I check if meat is cooked properly?

A digital meat thermometer is the most reliable method. Target internal temperatures: Beef rare 52°C, medium 60°C, well done 70°C. Lamb rare 54°C, medium 63°C, well done 72°C. Pork must reach 70°C minimum. Chicken must reach 75°C in the thickest part of the thigh. Insert the thermometer into the thickest part, away from bone.

Should I bring meat to room temperature before roasting?

Taking meat out of the fridge 30-60 minutes before cooking allows it to come closer to room temperature, which helps it cook more evenly. A large joint straight from the fridge will have a cold centre that takes longer to reach temperature, potentially overcooking the outside. For food safety, do not leave meat out for more than 2 hours.

BakeCalcs

Roasting Time Calculator

Calculate roasting time for beef, lamb, pork, chicken, and turkey by weight and doneness.

Joint Weight

Meat Type

Doneness

How We Calculate This

This calculator uses established UK roasting time formulas based on the weight of your joint and the type of meat. Each meat has a base time per 500g plus an additional fixed time. Doneness affects the per-500g rate for beef and lamb.

Resting time is calculated at 1 minute per 100g of meat, with a minimum of 10 minutes and maximum of 30 minutes. All temperatures are given as fan oven settings with conventional equivalents shown alongside.

Frequently Asked Questions

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Last updated: February 2026

All calculations are based on standard ratios and conversions. Results may vary with specific ingredients, equipment, and conditions.