Heat is integral to cooking, and just as measuring weights and volumes led to much better cooking at the start of the 20th century, measuring heat effectively leads to better cooking now. A good collection of thermometers are as important to making great barbecue as a good collection of measuring cups is to making great cookies.
How They Work
All thermometers are built around the same idea. A material changes in a consistent and particular way when the temperature changes, and we use some other measuring device to quantify that change. The classic (but not the first) is the mercury thermometer. Liquid mercury expands when heated, so a reservoir of mercury feeds a tube of constant diameter, and we read temperature results off a specialized ruler.
Jamming a bulb full of mercury into your roast is impractical at best, so engineers developed thermometers better suited to the job. Cut ahead a few generations to the present, and we’re using thermometers based on electrical effects. A thermistor takes advantage of the fact that electrical resistance changes with temperature. Precisely measure that resistance, and we can derive a temperature reading. A thermocouple uses a link of two wires of different materials that react differently to a temperature change. Via the Seebeck effect, this creates a very small amount of electrical potential that we can measure and convert to a temperature reading.
Either method produces a thermometer with a probe that’s super-thin and reads a precise temperature in a matter of seconds. The thermometers on sale now are amazing compared to those on the market just ten years ago.
Man Law's Guide to Buying Thermometers
There are a lot of different jobs around the kitchen that benefit from a good thermometer, so you’ll probably wind up with a few in your drawer over the course of time. Here’s a look at some of the important types and what to look for when you’re shopping.
The instant-read thermometer is probably the one that gets the most and broadest use. These are one-piece units with a sharp probe connected to a digital display. Insert the probe into the meat, and the temperature locks in within a few seconds. You’ll pull this out mostly to check if your meat is ready, both for safety and for taste. It’s also good for spot-checking anything else in the kitchen — bread doneness, fry oil temperature, stock that needs to be held below a simmer, sugar for candymaking, and more.
When buying an instant-read thermometer, your two top requirements are accuracy, read time, and probe thickness/depth. Accuracy to within two degrees does what you need; within one degree is better, especially if you like your steak medium-rare. If you want to spend a lot of money, you can get more accuracy, but unless you put the SCIENCE in food science, I don’t think it buys you anything.
Though the name of the style is instant-read, all these thermometers take a few seconds to get a reading (the coil thermometers we used to use took 30‒60 seconds to get a good read). Five seconds is good enough (if the meat is done, you’re going to rest it anyways, if it’s not done, five seconds off the heat won’t change anything), but you’d be happier around two seconds. x
Every time you jab your food with the probe, it does a little bit of damage to the meat. It’s mostly cosmetic, but a smaller probe is easier on your food. You should also know where in the probe the temperature sensor sits. The closer to the tip, the more control you have over your temperature reading.
Other things to look for include a good display with big readable numbers. A backlight is a plus. An instant-read is going to be in your hand around water and heat, so it should be resistant enough to those things that you don’t ruin your investment. It’s a small thing, but I give bonus points for working on ordinary household batteries. If the battery runs out, it’s better to be able to swipe a spare from the remote than have to go to the store and find the right button battery.
Where an instant-read thermometer is for making spot-checks on your food, a probe thermometer is for long-term monitoring. These come in multiple pieces, with one or more probes on a long heat-proof wire that connect to a main station. Some of these thermometers offer remote monitoring through a dedicated wireless receiver unit, or through an app on your phone.
Your use-case on a probe thermometer is long-cooking food, like a turkey in the oven or a pork butt in the smoker. You’ll put one or more probes into your meat, route the wires out the oven door/grill vent/smoker lid, and connect them to the base station. You’ll get a continuous temperature reading there and at any remote stations. Since you’re not expected to be paying close attention, you can set an alarm to alert you when a particular temperature is reached.
Some good general things to look for when buying a probe thermometer are accuracy, quality of the probes/wires, water/heat resistance of the base unit, and battery life. However, your biggest consideration is going to be how well its features match up with your application. If you’ve got an all-day smoking project with several pieces of meat, you might want multiple probes, remote data logging, thermostatic fan control, and every bell and/or whistle in the store. If you want to know when the turkey is done so your guests don’t croak, you need one probe with one alarm.
We’ll break this up into two main classes: do you want a standalone thermometer, or do you want a larger system for temperature logging and control?
If you want to keep it simple, look for a device that puts the information you need right in front of you. You want a sturdy unit with a big, legible display (backlight a plus) and a straightforward alarm interface. Multiple probes are still a worthwhile option here — put one in the turkey breast, another at the thigh joint, and a third one in the stuffing.
Multiple probes are the norm here. These units are usually for barbecue enthusiasts, so you’ll use probes in each piece of meat plus an ambient temperature reading. It’s a problem if your fire is too hot or too cold, so make sure you can set custom alarms in both directions for all the probes.
If this sounds like more than a few buttons on a control box can handle, you’re right. You need a good app, with an interface that doesn’t make you want to throw your phone through a wall. If you’re going to this kind of trouble, you want to be able to remember what you did. A good app should log, visualize, and let you annotate your results. They’re your road map to repeating your delicious work.
For feedback beyond an alarm, many of these units can drive a fan controller to automatically maintain temperature. If you’ve already got a thermostatic fan controller, make sure your thermometer system works with it; if you don’t, see if you like the selection of fans available.
RF vs. Wi-Fi vs. Bluetooth
Remote monitoring makes your life easier when it works, but you’ve got to choose the right style. A direct radio link is the simplest and most robust, but does the least. You’re probably just going to get one-way monitoring without control, but with no setup woes. A direct RF connection is going to do the best with construction that dampens signals.
Wi-fi gives you the most versatile connection to your phone, but it’s only as good as your wi-fi connection. Take your phone to where you plan to cook and make sure you get a good wi-fi signal before you commit. Wi-fi thermometers connect to a cloud server, so you keep logging even when your phone is out of range.
Bluetooth is somewhere in the middle. It’s a direct connection to your phone with a range of about 100 feet (less if there are walls in the way, sometimes a lot less). Setup is relatively painless, and you don’t need an internet connection in the loop. As long as you can get and maintain a reliable connection to your phone, you’re gold.
Best Instant-Read Thermometers for Cooking
Winner — Thermoworks Thermapen IR
Our old winner, the Thermapen, got better with the addition of an IR thermometer. The instant-read probe folds out to work at a variety of angles, and uses a thermocouple probe to measure temperature to within 0.7° (in normal cooking ranges) in 2-3 seconds. The probe is very small – just 0.06” wide at the business end. The display is big and easy to read. Even better, the display rotates as needed to match the orientation of the unit. It runs on two CR2032 button batteries, so make sure to keep some extras in the house. 1000 hours goes by before you know it.
The IR component is a bonus. IR thermometers let you measure temperature at a distance without contact. This is just surface temperature, so it can’t take the place of a probe, but IR is useful for checking the temperature on a pan or grill. It’s a great addition to your toolbox built into an already top-of-the-line unit .
Runner-Up — Thermoworks Thermopop
The Thermopop is a step down from the Thermopen, but at a quarter of the price it’s a great value. This unit keeps the price down by using thermistor technology instead of the thermocouple in the Thermopen. As a result, the Thermopop measures to within 2° (below 248°, less accurate above that) in 3-4 seconds. The probe is a smidge bigger (0.08”) too. The display is big and backlit, and can be rotated for easy reading. Like the Thermopen, this uses a CR2032 battery, but the simpler design makes it last a lot longer.
Best Probe Thermometers for Grilling
It’s true what they say — where there’s Smoke, it’s 🔥.
Sorry. The Smoke X4 is the best of the straightforward probe thermometers. The base unit connects four of the Thermoworks Pro-Series probes, and includes three meat probes and one ambient temperature probe (though you can swap those out for different models as you like). The base unit connects by direct RF to a remote monitor station. It advertises a line-of-sight range of 1.24 miles, which is useful for comparing to other models apples-to-apples, but not too relevant in practice. Our tests show it holds connection while obstructed by six houses, so it should work in all but the worst RF environments.
The thermistor probes are accurate to 1.8° in reasonable meat temperature ranges, and come with color-coded rings so you can know which one is which. Each channel can have a high and low alarm set, though with just a few buttons, you’ve got to press a lot of them to get what you want. The displays are big and legible, and the alarms are adjustable from off to very loud.
They do make the Smoke X2 version as well with room for just two probes, but the price break is small. The cost of the two extra probes alone is more than the savings you’d get by going smaller.
Want to go even simpler? The BlueDOT does one thing and does it well. One probe, one display, one alarm for maximum ease, and the price is right. If you can stand a little complication in your life, you can remotely monitor the device on your phone with a Bluetooth connection, but this works fine as a standalone.
The BlueDOT uses the same Pro-Series thermistor probes, accurate to 1.8°. The display is large and readable, and the controls couldn’t be simpler. The alarm is medium-loud, and the batteries are nice simple AAAs. The BlueDOT does a good job at a good price.
Best Probe Thermometers for Smoking
If you’re serious about barbecue, the Fireboard is equally serious about making your barbecue better. With support for six probes (the basic set comes with two food probes and one ambient probe) and the best fan unit on the market, the Fireboard took the smart step and offloaded all the controls into a first-rate phone app.
The Fireboard’s main communication is over Wi-Fi, with the temperature and control data synced to the cloud every 5 seconds. If Wi-Fi is unavailable, you can connect directly with Bluetooth. The app is the best out there for smoking, featuring detailed logs that you can annotate. Those logs are the key to remembering what you actually did and doing it again (or carefully avoiding it!), and you can access and share them anywhere. It pairs up with Google Assistant and Amazon Alexa for hands-free voice control too.
If there’s one knock on the Fireboard, it’s that you have to buy a separate waterproof case. You’re also committed to using the app for everything. You can view the temperatures on the control unit in a little display, but that’s it.
Runner-Up — Thermoworks Signals
The Thermoworks Signals is a great choice for barbecue too. It’s basically everything the Smoke X4 does right with Wi-Fi and Bluetooth control instead of an RF monitoring unit. It supports four probes (and comes with three food probes and one ambient probe) and the Billows fan controller. The Billows isn’t as good as the Fireboard blower, but it’s a solid way to automate your smoking session.
The Signals tries to cover all your bases by putting displays and controls on both the base unit and the phone app. The base unit has a great display that’s easy to read, but the controls are not as good as those found in the app. The app is pretty good, with easy-to-use controls and labels, but with less detailed logs than the Fireboard and no facility for annotations.
All in all, the Signals is a great thermometer system, but the Fireboard’s app is a solid step better, and that’s where you’ll be spending your time and effort.