Thermapen One vs MK4 vs ONE! - The Thermoworks Showdown

Thermapen and Thermoworks are some of the most trusted names in the instant-read thermometer market. With over two decades of experience in crafting some of the best and most beloved thermocouple thermometers around, Thermoworks' Thermopen line of thermometers has become synonymous with quick, accurate temperature readings for whatever you're cooking.

While Thermoworks' products are pricier than many comparable options available today, they are worth every penny, and if you're in the market for a new instant-read thermometer you can't go wrong with any of the Thermapen models. From the bare-bones Classic model to the former undisputed king of instant reads, the MK4, and now to its successor the ONE, Thermoworks really knows how to make a great meat probe.

Thermoworks Instant Read Thermometer Showdown!

These three thermometers, the Thermapen Classic, Thermapen MK4, and Thermapen One, represent some of the best options when it comes to a super-fast temperature reading.

The Thermapen classic is a bare-bones, stripped-down, Thermapen that manages to check almost every box on the list when it comes to wants and needs in a high-quality meat thermometer. At a relative value compared to the other thermometers in this matchup, the Classic does everything you'd want and won't break the bank along the way.

Once, upon a time the MK4 was the heavyweight champion of instant-read food thermometers. With a much-copied design, lighting fast readings, and incredible construction it's easy to see why this thermometer is the go-to option for pitmasters around the world.

Last, but certainly not least we have the Thermapen One, while the MK4 used to be king, these days the badest thermometer in the land is the One. With a slightly improved design from the MK4 and unbelievably fast, 1-second temperature readings, the Thermapen One has set what I feel is the standard for the instant-read probe thermometer.

Thermapen Classic

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What we liked:

• Snappy readings
• Great construction quality
• Auto on/off

What we didn't like:

• Runs on a button cell battery
• The screen doesn't auto-rotate
• No backlight
• No calibration

Look and feel.

The Thermapen classic like all the models on this list has what I like to think of as the "classic fold thermometer probe" design. With the introduction of the Thermapen, Thermoworks was one of the first companies to produce high-quality, folding probe instant-read thermometers, and companies have been copying the aesthetic ever since.

With a large, slightly squarish body, the Thermapen Classic looks great in a ton of different colors as do all the Thermapen models, but I was quite fond of the yellow finish on the Classic I was testing.

The LCD display is big, centered on the front of the thermometer body and the digits are easy to see and read. Other than the display the Thermapen has zero buttons or switches on the outside of the body. If you need to toggle between temperature format, from C° to F°, you'll need to look inside the battery compartment which is located on the backside of the body.

While many Thermapen models operate on a single AAA battery, the Classic for some reason uses a button cell battery and that is one of the few design choices I disliked on this thermometer. Almost everyone has a spare AAA battery lying around in case your battery runs down, most folks don't keep a button battery handy. It can be super annoying when the battery on your probe dies and you don't have the correct battery, but thanks to the auto-off design, the battery life is very strong overall.

Using the Thermapen Classic.

I decided to test the Thermapen classic, alongside the other Thermapen models during a brisket smoking session, and over the course of the 12-hour cook, I found the classic a joy to use.

The auto-on feature is convenient and even though the Thermapen Classic is the least expensive and feature-rich model in this comparison, it is head and shoulders above much of its competition.

Out of these three thermometers I was expecting that the Classic would be the slowest in terms of temperature readings and I wasn't wrong. However, it only took an average of 4.2s to achieve a stable reading, and compared to many other thermometers out there, that's pretty impressive.

The initial readings were always very close to the final stabilized temperature, usually within 5-10 degrees, which demonstrates how accurate the Type K thermocouple sensor is. Compared to traditional thermister style thermometers 4.2s is really impressive.

With a 4.5" stainless steel type K thermocouple probe, you can get to the heart of almost anything you might have on the smoker. The step-down design makes it easy to quickly pierce your product without losing moisture along the way. I took temperatures from almost every angle of my brisket and had zero issues reaching the center quickly and efficiently.

While the Thermapen classic might not have all the bells and whistles of its more expensive brothers, it is still an absolutely incredible thermometer in its own right. If you are looking for a dependable, workhorse of an instant-read thermometer then the Thermapen Classic should 100% be at the top of your list.

Thermapen MK4

We kept the MK4 in our review for comparison sake but it is no longer being produced and has been replaced by the improved Thermapen ONE.

What we liked:

• Really fast reading times
• Strong backlight with automatic low light sensor
• Auto on/off
• Runs on 1 AAA battery

What we didn't like:

• The battery compartment is awkward to access.

Look and feel.

Describing these thermometers is definitely repetitive, they are essentially identical in terms of the overall design, and other than some changes to the battery compartment, there is not a lot to distinguish between them.

Like the Classic and Thermapen One the MK4 has a large rectangular body with a large central LCD display. The display on the Thermapen Classic is fixed in orientation while the MK4 has the ability to rotate and be read 360° which can be really convenient.

While the Thermapen Classic runs on a button cell battery, the MK4 uses a single AAA battery as its power source, which I personally appreciate a ton. I hate running out of battery in a device or gadget only to realize it takes a super esoteric battery type that I don't keep on hand. Almost everyone has a spare AAA battery lying around, so it makes it easy when you inevitably run into a battery problem down the road.

While the AAA power source is nice, the battery life on these thermometers is really strong thanks to the auto-off feature. If the thermometer is open for longer than 10 minutes it will automatically shut itself off, and it also automatically powers down whenever you close the probe.

Though I do love the overall design of these thermometers, the battery compartment on the MK4 leaves a little to be desired. It is located at the bottom of the thermometer base instead of on the back as is the case with the Classic and the One. Because of its placement, it can be difficult to get your screwdriver situated properly to remove the screws keeping the compartment secure and waterproof.

Using the Thermapen MK4.

Testing these three thermometers side by side was a lot of fun. Beyond the fact that all Thermapens feel great in your hand and are super easy to use, these three thermometers really exhibit how far instant-read thermometers have progressed over the past few years.

While the Thermapen Classic is a great thermometer that does an awesome job providing quick, accurate readings. The MK4 really steps it up speed-wise. During my brisket smoke session, the MK4 averaged a reading time of 3.2s and all of the initial readings were within 5 degrees of the final stabilized reading.

The long, step-down probe makes it easy to take temperatures from the center of whatever you happen to be cooking, and the auto-rotate feature makes it easy to take temperature readings from any angle.

Personally, I love the buttonless setup and don't miss a control panel whatsoever. Thermapen really makes it easy to take temperatures without having to put a lot of thought into it. Simply insert the stainless steel probe into whatever your trying to temp, and wait for a second or two while the Thermapen works its magic.

One of the nicest features of all the Thermapen products is their waterproof construction. Thanks to tightly fitted joints/seams and screw fittings on the battery compartment the Thermapen line of thermometers are all IP6 waterproof rated which is great for cleanup. You can run your thermapen underwater without fear that you'll ruin your investment.

Many thermometers today come with the ability to self-calibrate them as they lose accuracy over time. Thermoworks doesn't offer a calibration function with their products and honestly, this is probably for the best. Though less expensive thermometers with cheaper thermocouples may lose accuracy over time, the Thermapen line all come with a NIST-traceable calibration certificate proving the quality of the calibration at the time of purchase. If you're worried your thermometer is getting less accurate do an ice water test to see how close it reads to the freezing point.

Thermapen One

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What we liked:

• Lighting fast readings, under 1s!
• Great display with auto-rotate
• Stronger backlight with a more sensitive low light sensor
• Runs on 1 AAA battery
• Awesome build quality

What we didn't like:

• Pricy

Look and feel.

As with the previous two models, it's clear the Thermapen One was built on the same general design specs. With a familiar square body, centered LCD display, and folding hinged stainless steel probe there's not a lot of substantive differences in the overall design of these thermometers.

While all three thermometers are similar, the One is definitely the most refined. With an auto-rotating display and low light sensing backlight like the MK4, the One is really well equipped. The backlight on the Thermapen One is stronger and more sensitive to light changes than the MK4 which is a nice improvement even though I didn't have any complaints concerning visibility when testing the MK4.

The battery compartment for the Thermapen One has migrated from the awkward bottom placement on the MK4 to a removable compartment on the back of the thermometer that's easier to access and replace overall. While not a huge deal, it's nice to see a company respond to user feedback and make adjustments in future models.

The stainless steel probe is the same Type K thermocouple probe available on all three of these thermometer models and measures 4.3" which is more than enough length to get to the heart of any product you might have on your barbecue.

One of my favorite elements of the Thermapen design is the incredible clean look. With zero buttons or controls on the face of the thermometer, it is incredibly easy to use. All you need to do is open the probe and you're ready to go.

The only real controls on these thermometers are found within the battery compartments, and they only allow you to toggle between temperature formats from C° to F°. Many other instant-read thermometers do come with calibration functions that are noticeably absent on the Thermapen line, but this is probably a good thing overall.

The ability to calibrate your thermometer can be convenient, but it can also lead to incorrect readings should you calibrate incorrectly. All the thermapen models come with a NIST-traceable calibration certificate, and in my experience, they continue to hold true to their calibration for years.

Using the Thermapen One.

Of all the Thermoworks meat thermometers I had the chance to test while preparing my Sunday brisket, I was the most excited to take the Thermapen One for a spin. I've been around grilling and barbecue for long enough that I've had the chance to use the Thermapen Classic and the MK4, but considering how new the One is, I hadn't had the opportunity to use it.

Overall, using the One was almost identical to using the MK4, other than the readings. While the MK4 consistently took extremely fast readings averaging 3.2s over the day, the Thermpen One was so fast I had to take multiple readings just to get my stopwatch started in time to capture it.

I didn't take a single temperature reading all day with the Thermapen One that took longer than 1 second and that is absolutely insane. These readings were so fast, that I didn't notice more than one to two temperature changes as the reading climbed before stabilizing.

The auto-rotate function was really convenient, and just like the MK4 you can read temperatures in 4 different directions as the readout rotates no matter which orientation you use.

One major improvement you'll find in the One versus the MK4 or the Classic is the level of accuracy in the temperature readings. While the Classic and the MK4 are accurate within .7°, the One improves upon that accuracy and drops it to accurate within .5° which is actually very impressive.

After a day of using the Thermapen one, it was crystal clear that this is the best probe thermometer I have ever used. While it is definitely pricier than the other models in this article and certainly more expensive than most comparable options, the Thermapen One is pound for pound the top instant-read thermocouple thermometer on the market today.

Which model should you buy?

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Thermoworks makes some of the best thermocouple thermometers I've ever used. The K-type thermocouple used in all of the Thermapen models is incredibly accurate. It far outstrips any probe with a thermistor sensor creating a faster more accurate thermometer overall.

Overall when it comes to thermometer choice it really depends on what you're looking for. The Thermapen "Classic" is an absolutely incredible thermometer for the price, and if you really want a Thermapen but don't want to break the bank along the way.

To be clear the this is not by any means an inexpensive thermometer. Thermapens are high-quality tools and even the least expensive model is going to cost more than your average meat probe. However, these thermometers will definitely help make your cooking process more accurate and precise, year after year.

While the MK4 isn't technically in production anymore you can still get it at a discount through Thermoworks. While slightly more expensive than the classic, I think it's the more attractive option. With awesome features like an automatic backlight with a low light sensor and autorotating 360 display. Again, this is a pricy thermometer but it's worth every penny.

The MK4 is definitely speedy, clocking an average of 3.2s in my tests, however, its successor is definitely the faster thermometer I've ever used. The readings provided by the Thermapen One are insanely fast. At an average of 1s throughout my testing, I rarely noticed more than a single reading change before it stabilized, and it was hard to get my stopwatch started and stopped in time to get an accurate measurement.

The MK4 may be going the way of the dinosaur, but the One is here to stay. As one of the pricier food thermometers on the market, the price tag can be shocking, but I can say with confidence this is, hands down, the best instant-read thermometer I've used to date.