A Short Guide to Food Thermometers

You can't tell if a food is safely cooked by sight, smell or even taste. A food thermometer is the only way to ensure food is cooked to the proper internal temperature and harmful bacteria are eliminated.

A food thermometer is needed for more than just meat and poultry. A safe minimum internal temperature must be reached to avoid food poisoning in all cooked foods. A food thermometer also is needed after food is cooked to ensure the temperature doesn't fall into the danger zone.

The temperature "danger zone" for perishable foods is between 40 degrees and 140 degrees Fahrenheit. Perishable foods are no longer safe to eat if they have been in this danger zone for more than two hours (one hour in 90°F or above). This is especially important for buffet and potluck-style gatherings where it’s easy to lose track of time and food may sit out for a longer period of time.

Choosing a Food Thermometer

There is a wide variety of food thermometers available. Pick the type best for you and remember to use it every time you cook:

• Dial oven-safe thermometers can remain in place as the food cooks. Insert 2 to 2½ inches deep into the thickest part of the food. Temperature readings are ready in one to two minutes. Use this type of thermometer for roasts, casseroles and soups. They are not good for thin foods.
• Instant-read thermometers aren’t meant to be left in the food while it cooks. Instead, use it to check food toward the end of cooking. Place the stem about 2 to 2½ inches deep in the thickest part of the food. This thermometer reads the temperature instantly, typically in 10 to 20 seconds. Used in roasts, casseroles and soups, and inserted sideways in thin dishes.
• Thermometer-fork combination thermometers are convenient for grilling and read the temperature of foods in two to 10 seconds. Place at least ¼ inch deep in the thickest part of the food, with the sensor in the fork fully inserted.
• Pop-up thermometers and disposable temperature indicators are meant for one-time use. These thermometers are often designed for specific temperature ranges, for example, the safe cooking temperature for hamburgers or turkey. These also read the temperature of foods quickly, in five to 10 seconds, when the material pops up or changes color. For best practice, also check the temperature of large items, such as whole turkeys, with a conventional thermometer.

How to Use a Food Thermometer

Before using a food thermometer, read the manufacturer's instructions. Read about how far to insert the thermometer in a food to get an accurate reading and whether it can remain in the food while cooking. Follow these simple steps to ensure you are correctly using a food thermometer:

• Step 1: Test it. Use either ice water or boiling water to confirm your food thermometer is accurate. Either method will help determine if the thermometer needs to be calibrated.
• Step 2: Calibrate it. Read the instructions to determine if the thermometer you intend to use can be calibrated. If so, it will indicate how to adjust the thermometer, as needed, to ensure you get an accurate reading.
• Step 3: Place it properly. Placement is very important to get an accurate reading. Place the food thermometer in the thickest part of the food, making sure not to touch bone, fat or gristle. The temperature may need to be checked in several places depending on the size and shape of the food being cooked, such as a roast, and with egg dishes and casseroles that are made with ground meat or poultry.
• Step 4: Don't rush it. Wait the recommended amount of time for your type of thermometer. For meat products including raw beef, pork, lamb, veal steaks, chops and roasts, use the food thermometer before removing meat from the heat source. For safety and quality, allow steaks, chops and roasts to rest for at least three minutes before carving or consuming.
• Step 5: Take care of it. Clean your food thermometer by hand with clean, hot, soapy water after each use, being careful not to immerse it in water. Washing it right away prevents cross-contamination and the spread of harmful bacteria, especially if the food is not done and needs to be checked again with the thermometer.

Correct Food Thermometer Placement

Begin checking the temperature toward the end of cooking, but before the food is expected to be "done." 

Using a food thermometer is only half the equation. Be sure to cook foods to the safe internal temperature. For fish, that’s 145°F or until the flesh turns opaque and flakes easily with a fork. Steaks, roasts and chops (whether they’re beef, veal, pork or lamb) should reach at least 145°F and rest for three minutes before serving. Any mixture using ground beef or pork, such as hamburgers, should reach at least 160°F, as should any egg dishes. Poultry products, whether whole or ground, should be heated to at least 165°F. Make sure leftovers and casseroles reach 165°F, too.