The best infrared thermometers allow you to take a temperature without touching the object, or person, in question. In times when disease is prevalent and hygiene crucial, there are obvious advantages – you can quickly test a whole group of people without constant cleaning. It’s a lot less, er, personal than some more established approaches too!
The benefits of an infrared thermometer are not useful just in the medical context. A non-contact thermometer (or pyrometer) can easily measure a huge range of temperatures; ones you certainty don’t want to touch, from industrial freezers, though cooking pots, kilns, or running engines. Moreover, by avoiding contact, you eliminate influencing the measurement (no heat exchange) or transferring dirt and germs if, for example, you were testing food before serving. But do note that thermometers designed for industrial use have a much, much wider temperature measurement range - so are not suitable for medical use.
All this is achieved by measuring infrared radiation from an object, a bit like a single-pixel infrared camera. Like cameras, there are a variety of features and prices, suited to different applications (if you want more pixels, check out our guide to the best thermal imaging cameras.)
Medical infrared thermometers
An elegant and popular choice, with a single button for a read out. Directed at the centre of the forehead from about 2cm (just under an inch), you can get an accurate reading and – unlike many more industrial designs – without a disturbing confirmation beep which, in practice, just annoys (or wakes) your kids. In a market swamped with just-good-enough packaging, it’s nice to find a quality document reminding you how best to use this kind of thermometer – specifically to measure the centre of the forehead, just above the nose, when dry. Sweat, even from a good cry, alters the texture of the skin which affects the measurement. The system algorithmically combines data from 100 readings plus a distance measure and an ambient temperature thermometer – all of which boosts confidence in the reading. Powered by 2xAAA batteries (included).
A Bluetooth and Wi-Fi connected smart thermometer, the Withings Thermo doesn't just take accurate readings from the arteries in the forehead, it records them too. Ideal, of course, for children who don’t enjoy oral, in-ear, underarm, or rectal measurements. The 20 x 5 pixel LED display looks futuristic, and it doesn’t just show the read out – swipe up to select the family member. Encouragingly this product has actually proven itself for a few years and, encouragingly, the app is still current (despite Nokia’s dubious management of Withings). There is a memory on-board for up to 32 readings, which can be transferred to an Android or iOS device (and, thanks to the wi-fi, distance is less of an issue than with Bluetooth-only devices). Oddly the app is limited to 8 profiles (unlike a similar model from Comper), but that’s enough for most families, and the real advantage of this system is the ability to record measurements to pass on to health professionals. Americans might also be pleased to know they can offset the high cost via FSA health plans without prescription.
While a forehead thermometer seems to embody the true ‘contactless’ dream of IR thermometers, there is much to be said for the in-ear measuring technique. This still uses IR measuring technology, but by pressing the probe into the ear using a disposable plastic guard you can push the accuracy to +/- 0.15˚C. There are 21 probe guards in the box, and 50 compatible ones cost about the same as a large latte (or rather more if you want Braun own-brand ones).
This thermometer also uses Braun’s “Age Precision” technology to remind you what is a ‘safe’ temperature – tap the button to cycle through ‘0-3 months’ ‘3-36 months’ and ‘over 36 months’ and, when you take a reading, you’ll get a color-coded backlight (green for OK, yellow for ‘elevated’ or ‘red’ for high. It might sound silly, but especially with young kids it’s helpful to be reminded of when to worry and when not to!
For cafes, stores and offices preparing to accept visitors after Covid-19 lockdown, a wall-mounted digital thermometer is an ideal solution, meaning customers (and staff) can be directed to take their own temperature with a polite sign, rather than be forced to queue for a team member with a handheld ‘gun’. There is a ‘fever alarm’ with beep beep sound and flashing light, which might seem a little unsubtle, depending on the ambiance, but otherwise operation is relatively painless – it can be connected to a USB lead to power it, and this will also provide enough charge for up to a week depending. Wall mounting is as simple as hanging on a nail or hook, though you might wish to take a little more care to prevent theft. The only real downside is choosing the right hanging height, especially if you welcome children.
Industrial infrared thermometers
The wide temperature range of this thermometer gun makes it suitable for an almost immeasurable number of applications, from checking the surface temperature of a pizza in the oven through automotive to HVAC (though not accurate enough for use on humans). The dual laser beams help target the right spot and the fact the narrow 30:1 beam means you can get a reading at a safe distance even in a furness or kiln. All customers will be happy to find a case and battery included. Professionals will also appreciate the Emissivity adjustment; the reflective properties of different materials affect IR thermometers, but experienced pros will find the ‘E’ toggle easy to use, as well as appreciating the ability to set max and minimum warnings. The LCD is adequate, too, though contrast could be better.
Ideal for use in electrical troubleshooting, HVAC, automotive and cooking and baking, this is a handy IR thermometer which still boasts some of the features of pricier rivals. You can take a continuous reading by holding the ‘trigger,’ or release to lock the result on screen, and the IR pointer will always make it easy to see where you’re getting your reading from. The Emissivity is fixed at 0.95, and of course the accuracy is certainly not medical grade, but as long as you work with that understanding you’ll still be able to, for example, check the surface temperature to cook the perfect steak, or locate problems areas with your home’s insulation that, once fixed, could save you more than the price of entry in heating bills!
The best thermal imaging cameras