How Do Meat Thermometers Work?

Why is it important to know how a meat thermometer works? Not all meat thermometers are the same. It’s important to know the difference because some types of meat thermometers are faster and more accurate than other types.  I will not only explain how different meat thermometers measure temperature but also how to use them correctly.

There are many different types of meat thermometers. For this discussion, I will focus on analog meat thermometers and digital meat thermometers. Analog meat thermometers are the classic glass dial-type thermometers that everyone’s grandma has in her kitchen.

Digital meat thermometers, on the other hand, run the gamut in terms of the technology they use to measure temperature. I will talk about the different types of digital meat thermometers in a little bit.

So, if you are curious about the meat thermometer that you have in your kitchen drawer, or if you’re looking to upgrade your current model, this post will help guide you in the right direction.

How does an Analog Meat Thermometer Work?

Your classic analog meat thermometer

Analog or dial meat thermometers have been around for a long time and do a decent job at measuring temperatures. They’re also known as bimetallic thermometers because they contain a coil inside the probe that is made from two different metals bonded together.

One of the two metals expands at a lower temperature than the other one causing the bimetal coil to turn. This coil is connected to the needle in the display. The needle will turn as the temperature goes up in the probe’s temperature sensing area.

The drawback of this thermometer is that the temperature sensing area of the probe is over 2 inches and displays the average temperature of this area. So for any meat that is thinner than this, you won’t get an accurate reading. So this rules out most steaks, pieces of chicken, fish, etc.  This thermometer works ok in larger roasts or soups in a deep pot.

Another drawback is that not only does the dial thermometer take up to a minute or two to reach a stable temperature, but it is also incredibly hard to tell the difference between the marks on the thermometer itself.  If you’ve ever cooked a piece of chicken you know that being off by a few degrees can be the difference between juicy and delicious and overcooked and dry.

These types of thermometers also need to be checked for accuracy regularly. These thermometers can be calibrated by adjusting the bolt underneath the dial display.

Keep this thermometer around as a backup thermometer, there are better options for you out there, which leads us to the wonderful world of digital meat thermometers.

How Does a Digital Meat Thermometer Work?

Lavatools Javelin PRO Duo Digital Meat Thermometer

A digital meat thermometer refers to any thermometer with a digital display readout. However, not all digital thermometers are created equal. There are three main sensor types that different digital meat thermometers can use to measure temperature.

These are thermocouples, thermistors, and resistance temperature detectors or RTDs. However, for our discussion today we will focus just on thermocouples and thermistors. I know it all sounds a little too sciencey but trust me, it’s not too complicated and worth knowing the differences between them.

Let’s take a look at these three different temperature sensing types. Each one has its advantages and disadvantages.

How do Thermocouple Meat Thermometers Work?

SmokeBloq Wireless Meat Thermometer

Thermocouple meat thermometers have the largest temperature range of all meat thermometers with better accuracy at temperatures higher than 300 degrees Fahrenheit. The temperature sensor is made from two different metal alloys welded together. Do you see a common theme here?

Just like the bimetallic thermometers mentioned before, thermocouple thermometers employ two different metals or alloys to measure temperature. However, the temperature sensing technology is totally different in thermocouple thermometers.

Thermocouple meat thermometers have two wires inside the probe (or sheath) containing different metals with different properties. The most common metals used are nickel and chromium. When they encounter heat the two wires produce an electrical voltage across them. This voltage is then measured and the voltage corresponds to a specific temperature which is then displayed on your thermometer’s digital display.

Thermocouple meat thermometers are fast and accurate. This is because the two wires with these different metals can fit in tiny areas towards the tip of the probe.

Thermocouple wires can be made smaller than any other competing thermometer technology such as thermistors. The closer to the heat source the faster and potentially more accurate your thermometer will be.

Examples of Thermocouple Meat Thermometers

You will mostly find thermocouple technology in higher-end meat thermometers such as Thermapens from Thermoworks and the SmokeBloq Thermometer pictured above.

I have a Thermapen as well as the SmokeBloq and they do a great job at measuring temperatures across all ranges.

One drawback of thermocouple meat thermometers is that they tend to be a little pricier than thermistor thermometers. However, you can still get a reasonably priced thermocouple meat thermometer. Thermopro makes a pretty decent one.

That brings us to thermistor meat thermometers. How are they different and why should you or I care? I’m glad you asked.

How do Thermistor Meat Thermometers Work?

If this discussion wasn’t nerdy enough for you, hold on to your pants, it’s about to get even nerdier. The main thing to remember when reading this is that heat makes it harder for metal to conduct electricity. This resistance can be measured and thus a temperature is given on your thermometer’s display.

And now for the scientific explanation. 

In a thermistor meat thermometer, an electrical current is sent through a wire in the probe that is connected to a resistor in the tip.  The resistor is a semiconductor that is made from ceramic. The resistor will then measure the resistance to the electrical flow when the temperature changes.

The thermistor’s change in resistance due to a change in temperature follows along with an expected formula or logarithmic curve that can be determined by the semiconductor. This semiconductor will calculate a temperature due to this electrical resistance it is experiencing.

Like most thermometers, the accuracy of thermistor meat thermometers depend on the quality of the components they’re made from. A thermistor meat thermometer can be very accurate and well-made with quality electrical components. They can also be very cheaply made with cheap electronics. The thermistor meat thermometer category thus falls under the classic “you get what you pay for” heading.

This is where reading reviews of a thermometer are important before purchasing. I’m not saying you can’t get a good thermistor thermometer in the $10-$15 range. You can. It depends on the manufacturer. You just have a higher chance of running into a dud of a thermometer in this price range.

Brands such as Thermopro and Kizen make some good thermistor thermometers with great reviews in this price range.

The Lavatools Javelin PRO Duo meat thermometer is an example of a high performing and accurate thermistor-type meat thermometer.

According to the company, “we use an exclusive high-performance Japanese thermistor sensor which matches thermocouple’s speed and accuracy at a lower cost.”

I can vouch for the speed of the Javelin Pro Duo, it’s close to matching the speed of the higher end Thermapen.

Now that we have figured out how a meat thermometer works, how do we go about using it properly?

How to Use a Meat Thermometer

Using three meat thermometers at once, EXTREME!

When you are using a meat thermometer you don’t want to take a reading from just one spot in the meat. Most people eyeball the center and stick their probe in, which works ok. However, most pieces of meat aren’t exactly symmetrical and even in terms of thickness. That’s why it is always a good idea to take a few different readings with your thermometer from different spots.

When you put your thermometer in the meat you are trying to find the lowest temperature reading possible. This will determine the point furthest from the heat and least done. Once you have found this spot, and it might take a few jabs to find it, you can adjust your meat or cooking temperature accordingly.

Too many probes in the turkey,? Perhaps.

Always make sure the thermometer probe isn’t hitting a bone or going through the other side of the meat. This will give you a skewed reading. That’s why taking the temperature in a few different areas will give you the best overall idea of the meat’s doneness. And don’t worry about losing too many juices because of the multiple pokes of the thermometer, that’s a myth.

When cooking turkey or chicken the best place to check the temperature is the deepest part of the thigh, right where it meets the main body of the bird.

For thinner pieces of meat or fish, your best bet is to insert your thermometer on the side and try to find the lowest temperature that way. You’ll cover more area of the meat by inserting from the side than just a shallow insertion from the top. The same thing goes for sausages.

Final Thoughts

Having an accurate meat thermometer not only helps you cook better food by serving it at the proper temperatures, but it also keeps you safe. It is a wise investment considering all the money wasted on food that is ruined or overcooked by freelance chefs on a yearly basis.

As you can see, not all meat thermometers are created equal and more often than not, you get what you pay for. If you have a meat thermometer at home and wonder if it’s accurate, there are ways to check it to make sure it’s still working properly.

If your thermometer isn’t up to snuff or you’re just looking for an upgrade hopefully this article helped point you in the right direction. Good luck and thanks for reading.