I love to cook. Followers know I like housewares better than all the disposable consumer electronics products to which I am exposed. This is because most houseware products are simple to use and do not wear out for years and years, if ever.

Thermapen ONE kitchen thermometer from Utah-based ThermoWorks is the new and upscale version of the recently discontinued Thermapen Mk4. Both fit within the “evergreen” category of long-lived, simple houseware products that are also at the top of their game.

Thermapen Mk4 is the award-winning food thermometer we bought a few years ago for about $100. This precisely calibrated kitchen essential is the undisputed champ in any respected product shootout that can be found BEFORE Thermapen ONE was introduced. With its 2-3 second time to read and display, I was very happy.

Before moving on, it is important to have an understanding of how these work and the general advantages to using either one.

When you “stick” the food with a thermometer, the tip reads the temperature. Simple? Well, no. Food has layers. Think of a nice, thick steak. I mean really thick, and then re-apply the logic to a thinner cut or a delicate piece of fish.

The first touch of probe-to-food is on the outside from the top or the side. With other thermometer technology, there can be a significant delay, and time matters. Also, many others do not have the 4-1/2 inch probe length of Thermapen ONE and Mk4. Now, imagine piercing and pressing through the food, through the layers to the center. Stop there in the thermal center. This is where the temperature is measured to determine doneness, right?

With the Thermapen ONE, as soon as the center is reached, the temperature appears on the display! Either remove the probe or press on, through to the bottom, in the case of top entry. Why check the bottom through the top? Whether on the grill or on the stove, the heat comes from the bottom and so long as the food is met with heat from the bottom, it is being cooked. The top cooks more slowly because the heat is on the bottom. And you need to know when it is time to turn it over. Food in the oven receives heat from all around, so the probe can accurately measure temperature in a few places to establish the state of doneness, depending upon the type of food. In a large, boneless roast of even proportions, find the center in a few places. In a chicken or turkey, find the center of the breast, but not against the bone. Always avoid probing close to the bone regardless of the food.

Now, let’s say you’re making a whole fish, a roast, a whole bird or parts. Bone in or no bone. The takeaway?  Each scenario is unique and requires practice in order to produce repeatable results.

Doneness is determined by temperature. And then, off the heat, most main course meats require resting until the meat is carved and served.

I hope this is making sense and you can visualize the processes.

Using Thermapen ONE, get in, get out and move on.

Add the most important characteristic – accuracy. Theremapen ONE is calibrated and certified accurate to within ± 0.5ºF. Combine accuracy with quick-reading for an unbeatable combination. But wait, there’s more!

Take the design, for example; the pocket knife-like way it opens bringing up the probe from its tip protected, nesting position, and turns on the display that is brighter than its predecessor.

Bakers need Thermapen ONE, too.


 The case is rugged and waterproof.

The display’s sensor always rotates the image to be right side up to the user (same as on the Mk4). See this at work in product images in this post.

The technology provides improved accuracy to ± 0.5°F (±0.3°C).

As the pointy probe pierces the food, real-time readings begin.

Here are the essentials of Thermapen ONE (from the manufacturer):

New: unparalleled speed with full temperature readings in less than one second.
New: industry leading accuracy to half a degree: ±0.5°F (±0.3°C).
New: brighter intelligent backlight display automatically illuminates in low-light and when the sensor window is covered.
New: easy-access battery housing uses one common AAA battery for a 2,000-hour battery life.
New: five-year warranty.
• Motion-Sensing Sleep and Wake Mode: intuitively turns on and off − on when picked up or in use and off when set down to save battery.
• Patented 360° auto-rotating display uses Accelerometer Technology to intuitively turn right- side up.
• Shockproof, dustproof, and waterproof with an IP67 rating for water-tight seals.
• Foldaway design protects probe when not in use.
• Biomaster Anti-microbial Silver Ion Technology reduces microbial growth.
• Hand washable.
• Display temperatures in °F or °C, 1° or 0.1° resolution.
• Includes NIST-traceable calibration certificate verifying accuracy to national standards.


  • Thermapen ONE by ThermoWorks
  • Calibration certificate
  • User Guide


Open it. The backlit display automatically comes on when it is opened to expose the fold-away pointy probe. The brilliant and thoughtful design comes to the forefront. Speaking of design, be wary of imitators. There is only one Thermapen ONE and it is from Thermoworks.


Over the past couple of weeks, we have grilled 2-1/2 inch thick boneless ribeye steaks, whole salmon and my favorite spatchcocked chicken. In the oven, we have made a vertically roasted chicken and a pork roast.

In my experience, chicken is easiest to gauge and measure. Even a few degrees one way or the other is not going to be the difference between a succulent and over- or underdone bird. The best test was with the fish, beef and pork.

I do not like overdone fish and the difference between just right and overdone can occur quickly. Ditto for steak. I’m a fan of rare. Overcooking can occur within a minute or two at high heat. Finding that thermal center with the probe tells the story quickly. Because steaks need to rest in order to hold in their juices, I pull them off at a reading of 120º. That way, even as some cooking continues once removed from the heat, I know mine will still be rare after a 20 minute rest. Others here like their beef more medium rare, with a temperature of 130º. Without Thermapen, my guesses are inaccurate. At the price of prime steaks, I really do not want less than perfection for everyone.

For the pork roast in the oven, I want medium well, NOT dried out and leathery well done, so I use Thermapen to tell me when the center reaches exactly 145º.

Precision and accuracy matter.

It did not take more than the above trials to convince me that Thermapen ONE is worth the investment.

See them side-by-side in action below in my water demo. Thermapen ONE on the right reacts faster, but not so much faster than the Mk4. I also like the battery access better on ONE. To replace the battery on Mk4, access is through an end opening.

While I can’t say that the Thermapen ONE is better than the Mk4, for those about to buy their ultimate kitchen thermometer, it makes sense to get the newest model and have it, use it, love it for many, many years to come.


Buy Thermapen ONE factory direct, available in a choice of 20 colors, and live happily ever after with this extraordinary and ultimate kitchen thermometer. Until stock is exhausted, Thermapen Mk4 is closeout priced! Have a look at YouTube instructional live class videos by ThermoWorks.


 FIVE year warranty.

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