ThermoWorks Thermapen ONE Review

ThermoWorks Thermapen One measuring steak temp on a grill

We’ve said many times: the single most important tool a cook can own is a reliable instant-read thermometer. The ThermoWorks Thermapen Mk4 has long been considered the gold standard of digital instant-read thermometers, and for good reason. The Mk4 was, in our opinion, the very best available….until now. Enter the latest version of the lightning-fast Thermapen lineup, the Thermapen ONE. The Thermapen ONE is the same basic design and shape as previous models but claims bragging rights to several added features over the earlier versions.

Thermoworks Thermapen One fits easily in your hand

First, the new and improved display without the orange background is brighter than previous models and ultra responsive. This makes the Thermapen ONE easier to read in low light situations. That becomes especially important in the fall when it gets darker much earlier in the day, or for those long overnight brisket or pork butt cooks.

Darkness shows the difference between the bright backlight on the Thermapen One and the orange backlight on the Mk4.
Thermapen ONE bright backlight compared to the Mk4 orange backlight.

Second, and possibly more important, the warranty is also improved on the new Thermapen ONE, by more than double its predecessor. It’s also 80% longer than competitors. The flagship models PT-75 from Maverick and the TP19X from ThermoPro for example, both come with a standard 12-month warranty. The ThermoWorks Thermapen ONE comes with a full five-year warranty, giving peace of mind to buyers.  

Next, access to the battery compartment is easier than previous models, and removing the cover also grants access to the user setting adjustments. With these controls, users can customize temperature scale, display resolution, sleep and wake settings, etc. The buttons are easy to manipulate, even for those with larger fingers. 

It's easy to remove cover of Thermapen One battery compartment and customize user settings

Finally, and in our opinion, the two most important improvements are accuracy and read time. When we first received this unit for testing some time back, it was hard to believe that accuracy and read time could be improved over the Mk4. ThermoWorks claims that accuracy has been improved from ±0.7° to ±0.5°. For our purposes, ±1° is acceptable, so cutting that in half gives some real breathing room. We conducted both ice bath and boiling water tests to prove or disprove the ThermoWorks claim and observed no deviation in expected temperature readings for the ice bath test, reading 32° F on the dot. The boiling water test was also without deviation at 211.2° F.

But water boils at 212° F so the Thermapen ONE was off by more than the claimed 0.5°, right? Actually, no. Water boils at 212° F ONLY at sea level. Using the boiling point calculator to account for elevation and barometric pressure, the boiling point of water in my location is exactly 211.2° F.

On to the biggest improvement, in our opinion: the read time. The Thermapen ONE gives an accurate reading in one second. Yes, ONE second. To be honest, we’ve been happy with the 2-3 second read times of the Mk4 for years. After using the Thermapen ONE for several weeks now, it’s hard to go back to the 2-3 second read times we were so happy with before.  

The ThermoWorks Thermapen ONE operates on a single AAA 1.5v battery and uses a micro thermocouple type of probe. Like the Mk4, the Thermapen ONE will be available in ten different colors. Every Thermapen ONE is tested before shipping and comes with a NIST-Traceable calibration certificate to ensure accurate temperature readings.   

Certificate of Calibration for Thermoworks Thermapen ONE

What We Loved

There’s an abundance of things to love about the Thermapen ONE, starting with the brighter display that really is helpful when cooking in a lower light situation. We didn’t expect this to be a huge difference, but it’s really nice. Game changing? No, but a nice feature to be sure. 

The 360° rotating display is terrific and shifts seamlessly, depending on the orientation of the thermometer. 

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The waterproof feature is certainly a plus; it’s rated at IP67, but the unit is not dishwasher safe. While not advisable, during testing the unit was accidentally left outside overnight during a pretty intense downpour, and it’s worked flawlessly ever since. 

The five-year warranty is better than any other unit on the market that we’re aware of. That alone makes this a very appealing unit, but there’s more we loved. The probe uses a micro thermocouple so small that it only needs to be inserted ⅛-inch into food for an accurate reading. Competitor thermometers often have to be inserted ½-inch or more for a reading. The advantage to the smaller sensor is that users can isolate exact temperatures in precise locations of the food they’re checking, whereas larger sensors take an average temperature of a larger location. This is especially important when taking readings from thinner cuts of meat.

The Thermapen ONE will be available in ten colors. For personal taste, that’s fun. More importantly, in the food industry many professionals use color coding as a safety measure to prevent cross-contamination by using only a certain color tool for certain types of foods. 

Finally, the one-second read time is something we’ve really grown accustomed to over the past few weeks of rigorous use. Not only is that convenient, but when you’re taking a reading over some seriously hot coals or burner, it’s nice to get the reading so quickly and not burn yourself or have to put on a pair of heat-resistant gloves.

What Could Be Improved

We tend to get picky with the reviews here and can generally find something that, at least in our opinion, could be improved. We’re hard-pressed to do that for the Thermapen ONE; there’s simply nothing, from a functionality perspective, that we think could be improved. Some might scoff at the $105 price point, but this is not an overpriced product considering what you get, especially with the five-year warranty. 

Who It’s For

The Thermapen ONE is for anyone who cooks. From pitmaster, to line cook, to executive chef or candy maker—this is a must-have tool. All cooks need a reliable instant-read thermometer in order to turn out consistent high-quality food, and the Thermapen ONE is the pièce de résistance in the lane of thermometers. 

Final Thoughts

When it comes to instant-read thermometers, you won’t find a better option than the ThermoWorks Thermapen ONE. This instant-read thermometer is a great value, even at the $105 price tag. The five-year warranty and sterling reputation of the brand make it a no-brainer for any chef, at any level. 

Thinking back to our satisfaction with the performance of previous models, we’re reminded of our once overwhelming satisfaction with the flip phone. The point is, we couldn’t realize how much we would appreciate the smartphone before it existed. We feel the same about the Thermapen ONE.

the Thermapen One displayed with its manual and features list.

2 thoughts on “ThermoWorks Thermapen ONE Review”

  1. Got it. It was so inaccurate that I thought I got a defective one. Returned it and the replacement was no better. Returned that and went back to the good ole reliable (and calibratable) mechanical meat thermometer. Bottom line, instant read thermometers are nor accurate or precise. If you want to chance food poisoning or under/overcooked steaks, then get it. Otherwise, save yourself $100+.

    1. You’re entitled to your own opinion Mike, but you’re not entitled to your own facts. This is just simply not true, and 10s of thousands of people would disagree with you.


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