How can you tell when a roast is done?
Trying to predict when a roast is done based on time is a very poor method. Many factors can change how long a particular roast takes to cook to your preference, including:
- Size and shape of the roast--generally the thickest dimension primarily affects how long it takes
- Initial temperature of the roast
- What temperature you cook it at
- The doneness you are aiming for (most important for beef or lamb)
Furthermore, there are two types of cooking commonly called roasts: pot roasts, which are a more properly a braised dish, and regular roasts. Finally, while not always called roasting, some oven cooked meats which are cooked for a very long time at low temperatures are in fact more similar in their chemistry to braising than to higher temperature roasting.
For braised dishes and low-and-slow barbecue type roasting, you can tell when the cooking is done because the meat is fall-off-the-bone tender.
For all other roasts, the best way to know it is done is to take the internal temperature with a probe or instant read thermometer.
The time guideline in recipes is to help you plan your cooking day logistics, and so that you know approximately how long to wait before checking for doneness. As in all but a few forms of cooking, the recipe times are not the final arbiter.
Pot Roasts and Braising
Pot roasts are cooked with liquid in the roasting pan, typically coming up about 1/3 to 1/2 the height of the meat. This is actually a type of braising, despite sometimes being called a roast dish, and is suitable for tougher cuts of meat like beef chuck, turkey thighs, or leg of lamb.
This is a moist cooking method intended to bring the temperature up high enough, long enough to convert the tough connective tissue to succulent gelatin.
These dishes are always well done. You know they are finished when the meat comes off the bone easily, and (when appropriate) shreds with little effort.
These dishes often braise for 45-60 minutes for dark meat poultry, or for 2-3 hours (or even more) for pork, beef, lamb, goat, and so on.
Low and Slow Roasting
Low and slow roasting, done with oven temperatures of approximately 250-300 F (120-150 C) on tougher meats--typically pork shoulder, beef chuck, brisket, and so on--has the same purpose as braising: it slowly converts the collagen to gelatin to create an unctuous dish. The difference is this roasting is done dry, not in liquid.
The test for doneness is also the same: when the meat comes off the bone easily, and shreds with little effort. The internal temperature will be at least about 180 F (82 C) and as high as 205 F (96 C) but this is not the primary indicator in low-and-slow.
The time to roast is very sensitive to the thickness of the cut, and the temperature at which the roasting is done. The roasting times can be very long, as the heat transfer is not as effective as with braising, up to 12 hours and even more depending on the item.
The remainder of this answer will concentrate on regular, high temperature roasting (as opposed to low-and-slow). In general the temperature will be at least 300 F (150 C), but usually 350 F (180 C) or higher.
In regular roasting, there may be a searing period of very high heat at the beginning or end of the roasting period to help brown and crisp the exterior of the cut.
The main indicator for when meat is done roasting is temperature. This is because the highest temperature achieved in the meat indicates how well it is cooked.
How to Measure
To measure the temperature of the roast, use an instant read or probe type thermometer in the thickest part of the meat. Try to aim the probe for the center, without touching bone.
For larger roasts, you want to aim for a measured temperature about 5 degrees F (about 2-3 degrees C) below your final target temperature. This is because the outside of the meat will be much hotter than the inside, and as the roast sits, the temperature will even out, raising the temperature at the center--this is called "carry over cooking."
- Take the temperature in several places, and use the lowest one as your result
- Leave the thermometer in until the result stops changing--depending on the quality and type of thermometer you have, this could take from 2-10 seconds or so.
What Temperature should I look for?
The temperature you are looking for depends on the type of meat you are cooking.
Red meat, including beef and lamb, can be roasted to different donenesses depending on how you prefer it.
125 F 49 C Rare 130 F 55 C Medium-rare 140 F 60 C Medium 155 F 68 C Medium-well 165 F 74 C Very well done
Most people expect most poultry to be thoroughly cooked (with the exception of duck breasts).
White meat should be cooked to about 155 F (68 C). Dark meat should be cooked, depending on your preference to at least 160 F (71 C) to as high as 180 F (82 C). It is far more resistant to overcooking than is white meat.
Note that duck breast is very unique among common types of poultry, in that it is a very heavily worked slow-twitch muscle: it is in fact, dark meat. Many people prefer it cooked medium rare or so. You can use the beef temperature chart above for duck breast.
Historically, especially in the US, pork has been cooked extremely well done because it was very fatty (which helps it seem moist), and to ensure it was cooked enough to prevent any food-born illness.
With leaner pork on the market, and far, far less risk of food born illness, it is becoming common to roast pork to lower temperatures.
It is safe after about 150 F (65 C), but many people find it more to their preference roasted to 155 or 160 F (68-72 C).
For more information, see:
This is a truly excellent answer, though I'd add one detail in these days when sous vide is becoming increasingly common. Namely: pot roasts/braising and "low and slow" roasting is more frequently done at lower temperatures for longer times. A 180F or greater internal temperature may have been typical for a braise or "low and slow" process in the past for food safety reasons. But with sous vide it is possible to cook large pieces of meat for longer times at a very precise temperature that will maintain safety. The goal, as you mention, is not temp, but tenderness and unctuousness.
If you want your roast or brisket to be fall apart tender, you must break the collagen down completely. Cook slow until internal temperature of meat is at least 195, then take off of the fire or oven. You should then be able to pull it apart with a fork and it taste so much better. Most people think that if you over cook a roast it will be tough, but you have to get the meat past that 165 of so threshold (it seems to stall a bit there). I cooked my last chuck roast for 7 hours on the stove top on a med-low setting and it was perfect.
I have read a lot of answers, but not one answered if your roast was in a roasting bag. For any beef with 2lbs of carrots and 2lbs of cut potatoes, the recipe is 18 to 22 minutes per pound of roast with everything in the bag at 375 degrees. If you have a 2lb roast with 1lb of carrots,1 lb of potatoes, then give it 1 hr and 30 minutes. 3lb of roast 1hr to 2 hrs depending on your oven. That's all if the internal temp is over 180 your good to live another day, and the kids are ok!