Free cooking time calculator. Scale roast cooking time for a different weight using the weight-ratio rule, with resting time included.
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Enter the base weight in kg and base cooking time in minutes from your recipe, then enter the new weight in kg and your planned resting time. The calculator scales the base time by the weight ratio raised to the power 0.6667 and adds the resting time to give the total time.
Most recipes give a cooking time for one weight, but the roast in your kitchen is rarely that exact weight. This cooking time calculator solves that problem by starting from your recipe, not from a generic table. Enter the base weight in kg and the base time in minutes from the recipe, then enter the new weight in kg. The tool raises the weight ratio (new weight divided by base weight) to the power 0.6667, which gives the scale factor, and multiplies the base time by that factor. That is how you scale roast cooking time for a bigger roast or a smaller roast, and it is also how you work out cooking time for different weight roasts without guessing. Because heat enters through the surface while weight grows with volume, time grows more slowly than weight, so doubling the weight does not double the time. The result is a scaled cooking time in minutes, plus a total time with resting time added, so you can plan the whole roast from oven to carving.
Competitor pages rely heavily on minutes per pound and minutes per kilogram tables, and those tables are useful as a cross check. A roast cooking time chart and a roast cooking time by weight chart both list a rate per unit of weight, plus sometimes a base time, for each meat. For example, many guides list turkey at about 13 to 15 minutes per pound unstuffed, whole chicken at about 20 minutes per pound, and beef roast at about 15 minutes per pound for medium rare. In metric terms, roast-time guides often list turkey at 40 minutes per kilogram plus 20 minutes, beef medium at 25 minutes per kilogram plus 25 minutes, and pork at 35 minutes per kilogram plus 30 minutes. Beef roast cooking time by weight tables vary by cut and doneness, so treat any chart as a planning guide and always confirm with a meat thermometer. This calculator takes a different route: it scales your own trusted recipe time, which avoids picking the wrong row from a generic chart.
Turkey is the meat people calculate most, so it deserves its own section. To answer how long to cook a turkey per kg, most UK guides use 40 minutes per kilogram plus 20 minutes at 180C, while US guides use a turkey cooking time per pound of about 13 to 15 minutes per pound unstuffed at 325F, or a turkey cooking time per kg equivalent in metric. That answers how long does a turkey take to cook in broad terms, but the exact answer depends on size and stuffing. Stuffed turkey cooking time runs longer than unstuffed turkey cooking time, often by 30 to 45 minutes, because the stuffing in the centre must also reach a safe temperature. Turkey breast cooking time is simpler, since a breast has no cavity, and many guides list it at about 20 minutes per pound at 325F. Turkey crown cooking time is also faster than a whole bird for the same reason: with no legs and no cavity, heat reaches the meat sooner, and guides list a crown at about 40 minutes per kilogram plus 20 minutes at 190C. Use the calculator to scale any of these known times to your bird.
Roast beef cooking time depends strongly on doneness. Guides commonly list beef at 20 minutes per kilogram plus 20 minutes for rare, 25 minutes per kilogram plus 25 minutes for medium, and 30 minutes per kilogram plus 30 minutes for well done, and the answer to how long to cook roast beef per kg changes with each level. Roast chicken cooking time and chicken roasting time per pound are usually listed at about 20 minutes per pound plus 20 minutes, or 45 minutes per kilogram plus 20 minutes at 200C, and the answer to how long to cook a roast chicken for a 1.5 kg bird is about 1 hour 30 minutes on that rule. Leg of lamb cooking time follows the same pattern as beef, at about 25 minutes per kilogram plus 25 minutes for medium. Pork roast cooking time is listed at about 20 minutes per pound or 35 minutes per kilogram plus 30 minutes, and roast pork cooking time per kg is the metric version of the same rule. Gammon cooking time is listed at about 30 minutes per kilogram plus 30 minutes, sometimes after boiling and finishing with a glaze. Scale any known time for these meats with this calculator when your joint weighs more or less than the recipe joint.
Cooking times are estimates, and a safe internal temperature is the only reliable finish line. Poultry, including turkey and chicken, must reach 165F (74C) in the thickest part of the thigh and breast, away from bone. Beef and lamb are commonly cooked to about 130 to 135F for medium rare and 140 to 145F for medium, while pork must reach 145F (63C) with a short rest under US guidance, or about 70C under many UK guides. This is why every serious roast guide repeats the same advice: use a meat thermometer, insert it into the thickest part, avoid bone and fat, and check more than one spot on a large bird. If you do not have a thermometer, do not guess from time alone: juices running clear, legs moving loosely, and meat pulling away from the bone are only rough signs, and they cannot prove safety. Always check with a thermometer before serving, and remember that all times on this page are estimates, not professional advice.
Resting time is part of the plan, not an afterthought, and this calculator adds it into the total time with rest. When meat leaves the oven, its internal temperature keeps rising for a while, which is called carryover cooking, typically by about 5 to 10F during the rest. That is why many cooks pull a roast a few degrees before the target temperature and let the rest finish the job. Resting also lets juices redistribute through the meat instead of spilling onto the board when you carve, which keeps the roast moist. Small joints such as chicken need about 10 to 15 minutes of rest, while larger joints such as turkey or large beef roasts need about 20 to 30 minutes, and very large turkeys may rest for up to 45 minutes. This answers how long should turkey rest before carving in practical terms, and it explains why the total time with rest on this page is longer than the scaled cooking time alone.
Oven temperature for roasting sets the pace for every time on this page. Most roasts cook well at about 180C (350F), with chicken and turkey crown often cooked a little hotter at 190 to 200C for crisper skin, and pork crackling started at about 220C for the first 30 minutes before reducing the heat. A fan oven usually runs about 20C hotter than a conventional oven, so fan users often reduce the temperature by that amount for the same time. This section also answers why did my roast take longer than expected, which is one of the most common competitor questions. The usual causes are a cold starting temperature, a thicker or more compact shape than the recipe joint, a bone in cut, stuffing, a crowded oven, or an oven that runs cooler than its dial shows. If your roast often runs late, check your oven with a separate oven thermometer, bring the joint to room temperature for 30 to 60 minutes before cooking, and start checking with a meat thermometer about 20 minutes before the calculated time.
Start with a recipe you trust and note its base weight in kg and its base cooking time in minutes. Weigh your own roast after trimming, enter that as the new weight in kg, and enter the resting time you plan to allow, for example 20 minutes for a large joint. The calculator returns the scaled cooking time in minutes, the scale factor, and the total time with rest, so you can work backwards from your serving time to find when the roast must go into the oven. For example, if your scaled cooking time is 90 minutes and your rest is 20 minutes, and you want to serve at 7 pm, the roast should go in by about 5:10 pm, allowing time for carving. Because this is a roast time calculator built around scaling, it works for any meat when you already know a good time for one weight. Check the result against a roast cooking time chart for your meat as a sanity check, then trust the meat thermometer for the final decision.
Use the weight ratio rule in this calculator: divide the new weight by the base weight, raise that ratio to the power 0.6667 to get the scale factor, then multiply the base cooking time by the scale factor. Add your resting time to get the total time. This works because cooking time grows more slowly than weight, so a roast twice as heavy does not take twice as long.
It depends on weight and stuffing. As a guide, an unstuffed turkey takes about 13 to 15 minutes per pound at 325F, or about 40 minutes per kilogram plus 20 minutes at 180C, so a 5 kg turkey takes about 3 hours 40 minutes. A stuffed turkey takes longer, often by 30 to 45 minutes. Always confirm 165F (74C) with a meat thermometer in the thickest part of the thigh and breast.
Rest a turkey for at least 20 to 30 minutes before carving, and up to 45 minutes for a very large bird. Cover it loosely with foil to keep it warm. Resting lets juices redistribute and lets carryover cooking finish the job, so the meat stays moist and carves more easily. The total time with rest from this calculator already includes the rest you enter.
No, resting time does not count as oven cooking time, because it starts after the meat leaves the heat, but it still matters for the final result. During resting, carryover cooking raises the internal temperature by about 5 to 10F, which is why many cooks pull meat a few degrees before the target temperature. Resting time is planning time, not oven time, and this calculator shows it separately in the total time with rest.
Roast pork should reach a safe internal temperature of 145F (63C) with a short rest under US guidance, or about 70C under many UK guides. Check with a meat thermometer in the thickest part, away from bone. Pork roast cooking time per kg is about 35 minutes per kilogram plus 30 minutes at 180C, but temperature, not time alone, decides when pork is done.
The most common causes are starting from fridge cold instead of room temperature, a thicker or more compact shape than the recipe joint, stuffing, a bone in cut, a crowded oven, or an oven running cooler than its display. Ovens commonly run 15 to 25F off their dial. Bring the joint to room temperature for 30 to 60 minutes, check your oven with a separate oven thermometer, and start checking with a meat thermometer about 20 minutes before the calculated time.
A whole turkey takes about 40 minutes per kilogram plus 20 minutes at 180C. Turkey crown cooking time uses the same rate, about 40 minutes per kilogram plus 20 minutes, but at a slightly higher heat of about 190C, and a crown usually finishes faster than a whole bird of the same weight because it has no legs or cavity slowing heat down. Turkey breast cooking time is about 20 minutes per pound at 325F. Always rest and check 165F (74C) with a meat thermometer.
All cooking times on this page are estimates for planning, not professional advice and not a food safety guarantee. Oven accuracy, meat shape, starting temperature, stuffing, and bone all change the real time. Always check with a meat thermometer and never rely on time alone, especially for poultry. If the thermometer reading and the timer disagree, trust the thermometer.
Stuffed turkey cooking time is longer, typically by 30 to 45 minutes, because the stuffing in the centre must also reach 165F (74C). Unstuffed turkey cooking time is about 13 to 15 minutes per pound at 325F, while stuffed turkey is about 15 to 17 minutes per pound. Many food safety guides recommend cooking stuffing separately in its own dish, which is safer and keeps the bird from overcooking while the stuffing catches up.
As a guide at 180C, roast beef takes about 20 minutes per kilogram plus 20 minutes for rare, 25 minutes per kilogram plus 25 minutes for medium, and 30 minutes per kilogram plus 30 minutes for well done, with about 20 minutes of resting time. Beef roast cooking time by weight varies by cut, so use these rates as a cross check for your scaled recipe time and confirm doneness with a meat thermometer: about 50C for rare, 60C for medium, and 70C for well done.