The Ultimate Guide to Cooking Thermometers

Every year, roughly 48 million Americans get sick from foodborne illness. About 128,000 end up in the hospital. Around 3,000 die. The economic toll runs to an estimated $75 billion annually in medical care, lost productivity, and premature death.

A cooking thermometer could prevent many of those cases. The USDA's Food Safety and Inspection Service is blunt about it – using a food thermometer is the only reliable way to know your food has reached a safe internal temperature. Color, firmness, and juices tell you almost nothing about safety. In one USDA study, 21% of participants relied on visual cues like color and grill marks to check if their hamburgers were done. That approach fails often enough to matter.

And yet, according to the FDA and USDA's 2019 Food Safety Survey, only 62% of American adults even own a food thermometer.

This guide covers everything you need to know about cooking thermometers – what types exist, how they work, where to place them, what temperatures to target, and how to keep them accurate.

Types of Cooking Thermometers

There are several categories of cooking thermometers, and each serves a different purpose. The two broadest categories are instant-read thermometers – which you insert briefly to check a temperature - and leave-in thermometers – which stay in the food throughout cooking.

Digital Instant-Read Thermometers

Digital instant thermometers are the workhorses of the home kitchen. You insert the probe into food, wait a few seconds, and read the temperature on a digital display. The USDA's FSIS notes that digital instant-read thermometers can register a temperature in about five seconds. The sensor sits at the tip of the probe, which means they work well for thin foods like hamburger patties and chicken breasts. They should not be left in food during cooking unless the manufacturer specifies otherwise.

There are two main sensor technologies inside digital thermometers.

Thermistors use a semiconductor that changes electrical resistance as temperature shifts. They are the more common technology in consumer-grade kitchen thermometers.

Thermocouples use two different metal alloys joined at one end. When the junction experiences a temperature change, it generates a small voltage proportional to the temperature difference. Thermocouple thermometers tend to read faster (often within one to two seconds) and are generally more accurate, especially over time. Professional kitchens favor them. The tradeoff is price. A quality thermocouple thermometer typically costs more than a thermistor-based model.

Dial (Bimetallic) Instant-Read Thermometers

These older-style thermometers use a coil of two bonded metals that expands and contracts with heat, moving a needle on a dial. They take longer to register a temperature, usually 15 to 20 seconds according to FSIS. Their sensing area runs along two to three inches of the probe stem, so you need to insert them deeper than a digital thermometer to get an accurate read. They work best for roasts, casseroles, and soups where you have enough depth. For thin foods, they are less practical. On the positive side, most dial thermometers can be manually calibrated using the nut beneath the dial head.

Oven-Safe (Leave-In) Thermometers

These thermometers are designed to stay in food while it cooks. You insert the probe before putting the food in the oven, on the grill, or in a slow cooker, and monitor the temperature without opening the door. Some are dial models with large faces that you can read through an oven window. Others are digital models with a probe connected by a heat-resistant cable to a base unit that sits outside the oven. The base unit often includes programmable alerts that sound when your target temperature is reached.

Wireless and Smart Thermometers

Wireless and smart thermometers are a newer category. These use Bluetooth or Wi-Fi to transmit temperature data from a probe inside the food to a phone app or standalone receiver. Some models use multiple sensors along the probe to better identify the coldest point in the meat, which is the spot that matters most for safety. The advantage is that you can monitor your cook from another room or even outside. The USDA's FSIS factsheet on food thermometers notes that wireless and smart thermometers allow cooks to focus on other tasks without constantly checking the food.

Candy and Deep-Fry Thermometers

These are built for high temperatures. A standard meat thermometer often tops out around 200 to 220 degrees Fahrenheit. Candy and deep-fry thermometers can measure up to 400 degrees Fahrenheit or higher. They clip to the side of a pot and have long probes designed to stay submerged in boiling sugar or hot oil without the cook getting burned. In candy making, the difference between fudge and caramel is a matter of about 10 degrees. The Exploratorium's candy-making guide describes how sugar syrup passes through distinct stages as water evaporates and sugar concentration increases: thread (230 to 234 degrees Fahrenheit), soft ball (235 to 240), firm ball (245 to 250), hard ball (250 to 265), soft crack (270 to 290), and hard crack (295 to 310).

Oven and Grill Thermometers

Oven and grill thermometers do not measure the temperature of the food. They measure the air temperature inside your oven or grill. That matters because oven dials are often inaccurate. An oven thermometer hung from a rack will reveal hot spots and tell you whether your oven runs hot or cold. They are simple, cheap, and surprisingly useful.

Safe Internal Temperatures

The USDA and FSIS publish clear minimum internal temperatures for different foods. These temperatures exist because they destroy the pathogens that cause foodborne illness. Most pathogens die between 140 and 165 degrees Fahrenheit, but the specific recommendation depends on the type of food.

Here are the current USDA recommendations:

Beef, pork, veal, and lamb (steaks, chops, roasts): 145 degrees Fahrenheit with a three-minute rest time. The rest matters. During those three minutes after removal from heat, the internal temperature stays constant or continues to rise, which destroys additional bacteria. The USDA lowered pork's recommendation from 160 to 145 degrees Fahrenheit (with the three-minute rest) because research showed that combination is equally safe and produces juicier results.

Ground meats (beef, pork, veal, lamb): 160 degrees Fahrenheit. No rest time required. Ground meat needs a higher temperature because the grinding process can spread bacteria from the surface throughout the meat.

All poultry (whole birds, parts, ground): 165 degrees Fahrenheit. For whole birds, the FSIS recommends checking the innermost part of the thigh, the wing, and the thickest part of the breast.

Fish and shellfish: 145 degrees Fahrenheit.

Egg dishes: 160 degrees Fahrenheit.

Casseroles and combination dishes: 165 degrees Fahrenheit.

Leftovers and reheated food: 165 degrees Fahrenheit.

One point the USDA makes repeatedly: you cannot judge safety by color. Ground beef can turn brown before reaching a safe temperature. Research showed that one in four hamburgers that looked fully cooked had not actually reached 160 degrees Fahrenheit. Pink pork that has reached 145 degrees with a rest is perfectly safe. Color tells you about chemistry, not safety.

How to Use a Cooking Thermometer Properly

Owning a thermometer only helps if you use it correctly. The USDA's FSIS provides specific guidance on placement, and the advice comes down to a few principles.

Placement

Always insert the probe into the thickest part of the food. Avoid bone, fat, and gristle, all of which conduct heat differently than muscle and will give you a misleading reading. For whole poultry, check the innermost part of the thigh, the thickest part of the breast, and the wing. For thin foods like hamburger patties and chicken breasts, insert the probe sideways through the edge so the sensor reaches the center. The FSIS suggests removing thin foods from the heat source and placing them on a clean plate before inserting the thermometer sideways, to avoid burning your fingers.

For casseroles and combination dishes, place the thermometer in the center. If the dish contains eggs or poultry, check multiple spots to confirm even cooking.

Reading

Wait for the reading to stabilize before pulling the thermometer out. With digital instant-read models, that usually takes about five seconds. With dial models, it takes 15 to 20 seconds. Taking the probe out too early gives you a number that is still climbing.

Multiple Checks

Take the temperature in more than one spot, especially with large cuts and whole birds. The thermal center of a roast can vary depending on shape and bone structure. A single reading does not guarantee the whole piece of meat is done.

Thin Foods

For thin items like sausages, pork chops, and thin chicken breasts, insert the probe through the side of the food so the entire sensing area sits in the center. This is especially important with dial thermometers, whose sensing area extends two to three inches along the stem.

Calibrating Your Thermometer

A thermometer that reads two or three degrees off is not a big deal for a steak. But for candy making or for food that is right at the safety threshold, accuracy matters. The USDA recommends two calibration methods.

Ice Water Method

Fill a glass with ice cubes. Add cold water and stir. Submerge the thermometer stem at least two inches into the mixture without touching the sides or bottom of the glass. Wait at least 30 seconds and check the reading without removing the stem. It should read 32 degrees Fahrenheit. If it does not, adjust according to the manufacturer's instructions. Many dial thermometers have a calibration nut beneath the dial head that you can turn with pliers while the probe is still in the ice water.

Boiling Water Method

Bring a pot of clean water to a full rolling boil. Insert the thermometer stem at least two inches deep without touching the sides or bottom. Wait at least 30 seconds. The reading should be 212 degrees Fahrenheit at sea level. At higher altitudes, water boils at lower temperatures, so you will need to know the boiling point in your area and adjust accordingly. The FSIS recommends using distilled water for true accuracy.

When to Calibrate

The general guidance is to check your thermometer whenever you drop it, whenever it goes through a severe temperature change, and periodically as part of routine maintenance. For dial thermometers, check before every major use. For digital models, check weekly or monthly depending on how often you cook. If your digital thermometer does not have a reset or calibration function, check the manufacturer's instructions. Some cannot be calibrated at home and need to be returned to the manufacturer or replaced.

Choosing the Right Thermometer

The type of cooking you do most should drive your choice. If you mostly cook weeknight meals with chicken, pork, and the occasional steak, a good digital instant-read thermometer is the single most useful kitchen tool you can buy. Look for one that reads quickly (within two to five seconds), has an accuracy of plus or minus one or two degrees Fahrenheit, and has a probe thin enough for thin cuts of meat.

If you smoke meat, braise, or do a lot of roasting, add a leave-in probe thermometer with programmable temperature alerts. Being able to set a target and walk away is worth the extra cost.

If you make candy, fudge, caramel, or do deep frying, you need a thermometer rated for high temperatures. Most dedicated candy thermometers clip to the pot and can read up to 400 degrees Fahrenheit. Some high-end digital instant-read thermometers have wide enough ranges to handle candy making too.

And if your oven has never been checked against an actual thermometer, spend a few dollars on an oven thermometer. You may find that your oven runs 25 degrees hot or cold, which explains a lot of past baking frustrations.

Common Mistakes

Checking too early. If you pull the probe out before the reading stabilizes, you get an inaccurate number. Wait for it.

Touching bone or fat. Both conduct heat faster than muscle tissue. A probe resting against a bone will read higher than the actual temperature of the surrounding meat.

Using the wrong thermometer for the job. A meat thermometer in a pot of boiling sugar will top out before you reach the soft ball stage. A candy thermometer jammed into a chicken breast is overkill and probably too long to be practical.

Never calibrating. A thermometer that reads four degrees low means you are pulling food off the heat before it reaches a safe temperature. A thermometer that reads four degrees high means you are overcooking everything.

Relying on color. Repeat it until it sticks: color does not tell you whether food is safe. Pink pork at 145 degrees Fahrenheit is safe. Brown hamburger at 140 degrees is not.

Beyond Meat: Other Uses for Kitchen Thermometers

A good thermometer is useful for more than checking if chicken is done.

Bread baking. Internal temperature tells you when bread is truly finished. Most loaves are done between 190 and 210 degrees Fahrenheit, depending on the type. This is far more reliable than tapping the bottom and listening for a hollow sound.

Tempering chocolate. Chocolate must be heated and cooled to specific temperatures to achieve a smooth, glossy finish with a clean snap. Dark chocolate is typically tempered between 88 and 90 degrees Fahrenheit. A thermometer makes this process manageable instead of mystifying.

Oil temperature for frying. Maintaining consistent oil temperature is the difference between crispy fried food and greasy fried food. Most frying happens between 325 and 375 degrees Fahrenheit. A thermometer clipped to the pot keeps you in the right range.

Water temperature for coffee and tea. Some green teas should be brewed at 175 degrees Fahrenheit. Pour-over coffee is best between 195 and 205 degrees. An instant-read thermometer lets you hit these targets without guessing.

Proofing bread dough. Yeast works best in a specific temperature range, typically 75 to 80 degrees Fahrenheit. Checking the temperature of your proofing environment with a thermometer can help you troubleshoot dough that rises too fast or too slowly.

The Short Version

Buy a digital instant-read thermometer. Use it every time you cook meat, poultry, or fish. Insert it into the thickest part, away from bone and fat. Wait for the reading to stabilize. Check it against an ice water bath every so often to make sure it is accurate. If you do this, you will cook safer food and better food. A thermometer removes the guesswork from the one question that matters most in cooking – is it done?