Cat S61 review

With thermal imaging and laser measurement, the Cat S61 is no mere phone

Not everyone will exploit the Cat S61’s considerable talents, but those that do will likely find it invaluable.
Not everyone will exploit the Cat S61’s considerable talents, but those that do will likely find it invaluable.
Not everyone will exploit the Cat S61’s considerable talents, but those that do will likely find it invaluable.


  • Rugged and water resistant
  • Thermal imaging camera
  • Long battery life
  • Useful measurement tools
  • Air quality sensor


  • Very expensive
  • Heavy and chunky
  • Sluggish at times

The Caterpillar brand has long been associated with construction machinery and equipment, but the company has successfully licensed that brand out to a wide variety of different manufacturers producing everything from boots to smartphones.

British smartphone manufacturer the Bullitt Group is behind the Cat series of phones and it has found success by targeting a niche audience and building them a device that serves their needs. The Cat S61 is the latest refinement in the flagship series and it’s aimed squarely at people who need a rugged device for tough environments.

This is a chunky tank of a phone, capable of surviving falls, bumps, and dunks without a case. Bullitt has gone further than that by packing in thermal imaging, laser measurement, and even air quality sensors to serve engineers, plumbers, builders, farmers, the military, and other groups seeking a particular set of skills from their phones. Here’s what it’s like to use it.

Built like a tank

It’s immediately clear when you pick the Cat S61 up that it has been designed to be tough. A thick, matte aluminum frame with a glossy edge contrasts with the black plastic, and a distinctive, angled protrusion at the top bears the Cat logo.

The 5.2-inch display has three physical buttons below it for access to back, home, and recent apps, enabling you to navigate the Android interface even if your hands are wet or dirty. There’s a polycarbonate lip around the screen to prevent it from touching down if you drop your Cat S61; it also comes with a screen protector already applied over the Gorilla Glass 5 display.

It’s an average IPS LCD with a 1,920 x 1,080-pixel resolution. We found it comfortable to read on for long periods, but the brightness struggled with sunny outdoors and we frequently had to override the auto-brightness and crank it up.

This is a chunky tank of a phone, capable of surviving falls, bumps, and dunks without a case.

On the bottom edge there’s a speaker and a flap that opens to reveal the USB-C charging port. On the right you’ll find a textured power button with the separate volume buttons further down. There’s an orange programmable key on the left edge, which offers a handy physical shortcut. It can be used for a push-to-talk mode, or you can map two different functions like the flashlight and answer or end calls to short and long press. There’s also another flap that conceals the SIM and MicroSD card tray. Up top there’s a final flap with the standard 3.5mm audio jack behind it.

Flipping over to the back, the protrusion accommodates the Flir camera sensor for thermal imaging which sits above the regular 16-megapixel camera lens. There’s a subtle Flir logo next to it, but it’s the big, shiny Cat logo that will catch your eye. At the bottom left there’s the laser lens for measuring distances.

The back is textured for enhanced grip, and it’s a pretty comfortable phone to hold, though it does weigh a staggering 260g (9.17 ounces). To put that in perspective the iPhone X weighs 174g and even the Samsung Galaxy S9 Plus, with its 6.2-inch display, only weighs 189g.

You’ll generally want two hands to use this phone, but there is an advantage to all this bulk – the Cat S61 is seriously tough. It can handle falls from up to 1.8 meters (6 feet) onto concrete, temperature ranges from -13 degrees Celsius to 131 degrees Fahrenheit (that’s -25 to 55 Celcius), and even salt mist spray.

It’s also IP68 and IP69 rated. That means it can be submerged in water at a depth of up to 3 meters (almost 10 feet) for up to one hour, and it’s also protected from close-range high pressure or high temperature water jets. The touchscreen still works when your fingers are wet and there’s a handy glove mode, so you can use it with gloves on.

We don’t like to deliberately abuse phones, but we did drop the Cat S61 a couple of times and the only sign of its mishap was a tiny ding in the metal frame. If you need a phone that you can use in dusty, dirty, or wet conditions without worry, then we think you’ll struggle to find anything better than the Cat S61. Even if you apply a seriously rugged case to another smartphone it’s going to lack the physical buttons that make this phone so usable in any conditions.

Budget performance

The Cat S61 has a Qualcomm Snapdragon 630 inside that’s backed up by 4GB of RAM. You’ll also find 64GB of storage and a MicroSD card slot that allows for expansions of up to 256GB.

We can’t hide our disappointment about the performance of this phone. Navigation is generally smooth, but there is some definite lag loading up certain apps and when switching between apps. When we played PUBG: Mobile it recommended the lowest graphical settings and it was still glitchy. We didn’t have problems with Super Mario Run, but it was slow to load.

Here are the benchmark results:

  • AnTuTu 3DBench: 89,470
  • Geekbench CPU: single-core 874; multi-core 4,182
  • 3DMark Sling Shot Extreme: 712

The closest phone we’ve tested recently is the Moto G6 Plus, which managed 90,483 in AnTuTu, 4,167 for Geekbench, and 709 for 3DMark. That shouldn’t be a big surprise because the G6 Plus has the exact same processor and RAM as the Cat S61. The problem here is that the Moto G6 Plus costs about $360 (270 British pounds), whereas the Cat S61 costs $1,000 (800 British pounds). Looking at another phone in the same price bracket, like the iPhone X, we see much higher scores of 206,010 for AnTuTu and 9,877 for Geekbench. Samsung’s Galaxy S9 Plus, which will cost you $840, scored 263,591 on AnTuTu and 8,191 on Geekbench.

To accommodate some of the unique extras the Cat S61 offers, the Bullitt Group has had to compromise in other areas and performance is one of them.

Digital toolbox

The Cat S61 ships with Android 8.0 Oreo and our review unit has already been updated to Android 8.1. A commitment to the Android P update has also been made, so you’re getting the latest flavor of Android with this phone.

You also get a thoughtful array of extras. The integrated Flir camera provides Predator vision with hot spots showing up bright white and orange, while cold spots are darker and blue. You can take pictures in the Flir app and they’re in HD now – the Cat S60 was limited to VGA quality. It’s also capable of showing from -20 to 400 degrees Celsius (-4 to 752 degrees Fahrenheit).

Hot spots show up bright white and orange, while cold spots are darker and blue.

It’s enormously fun to play with around the home or when you’re out and about, but for many professionals it can prove useful. Mechanics can see engine temperatures, plumbers can see hot water pipes, and security guards can see people lurking in the bushes nearby. Vets have also been known to use the thermal imaging to identify incorrectly fitted horseshoes, as it can highlight internal swelling. There are many other potential applications.

There’s also a built-in laser measurement tool. We found it easy to calibrate, simply point the red dot at a spot where you want to know the distance – easiest from a desk or table top to the floor. Once calibrated you can use it to measure distances fairly accurately. There’s even a shape tool so you can measure areas to calculate things like how many tiles you might need to cover a portion of wall.

We compared the results to our tape measure and found it to be close enough for quick estimates. It was generally within an inch for longer distances between 2 meters (around 6 feet) and its maximum range of 8 meters (26 feet), but it’s more accurate at shorter distances of 2 meters and under. If you’re a tiler or a carpenter quickly sizing up a job, the Cat S61 could come in very handy.

The final headline tool is the air quality sensor. It’s a Volatile Organic Compound sensor (VOC) designed for indoor use, and it’s capable of picking up a range of contaminants. If you’re working with cleaning products, painting, or plastering perhaps, it will alert you when more ventilation is needed. It can also show temperature and humidity data, so you no longer have to watch paint dry – the Cat S61 can do it for you.

Your average person probably won’t have much use for the air sensor, but it is interesting to see what it thinks of your air quality as the data is collected and graphed over time. It did also give us a fright one night when we got an air quality alert while reclining on the couch watching TV. There was no obvious cause, but we cracked a window just to be safe. It’s tough to vouch for the accuracy of this tool, but we can see decorators appreciating it.

Your average person probably won’t have much use for the air sensor, but it is interesting to see.

There is also an app toolbox on the Cat S61 which highlights a vast array of apps that you might find useful. They’re divided into categories, so there are suggestions for construction, farming, fishing, hiking, and a few other activities.

Apart from that we’re pleased to find Google’s suite of apps present and correct ready to serve as your defaults. Though one thing we ran into trouble with was Smart Lock. The Cat S61 lacks a fingerprint sensor, which means you’re stuck with a PIN or pattern for unlocking it if you want some security, and it’s incredibly tedious having to enter a PIN every time you want to unlock your phone. We opted to set up trusted locations and tried face unlock, even though it’s not very secure, but both only worked intermittently. We had to keep deleting them and setting them up again or resign ourselves to using the PIN. This could be a Google bug, but whatever the cause it was one of the most annoying things about using this phone daily.

Fantastic battery life

The perfect phone for a hard-working person is going to have to have some serious stamina, and we’re pleased to report that no corners have been cut in this department. The Cat S61 has a 4,500mAh battery inside and it can easily go for two days between charges, maybe even three with light use.

cat s61 iphone comparison
Simon Hill/Digital Trends

When it does finally run out of steam, you can pop open the flap and plug in the USB-C charger, which supports Quick Charge 3.0 to juice it up again rapidly. Just 15 minutes or so will get you a few hours of light use and it takes somewhere around 2 hours to fully charge from about 20 percent. The Cat S61 can also support Quick Charge 4.0 with the right charger and cable, but it’s a QC 3.0 charger you get in the box.

As usual, graphically-intensive games chew through the battery more quickly. We also found that the Flir thermal imaging camera is a serious battery hog, so if you plan to use it for more than a couple of minutes, just be aware that you’re going to need to plug in soon after.

Camera compromise

The last Cat phone we reviewed, the Cat S41, had a disappointing camera, so were interested to see how the 16-megapixel shooter in the Cat S61 would perform. It is a bit slow to load, slow to capture a shot, and slow to process and save it, but we were able to get some pleasing photos on a beautiful summer’s day.

We were impressed with the level of detail on close shots, and it produces a nice bokeh effect with the background blurred. Wider shots often look overexposed, and this was also a problem for shots of people and animals.

As soon as the light drops, bigger problems kick in. The lag in the viewfinder is multiplied to almost unusable levels. Low light shots have a lot of noise and the slightest movement produces blurring.

One advantage of the rugged body is the underwater mode for the camera in the Cat S61. You can use the volume buttons to switch between front and back, video and photo, and to capture. It worked well in the bath, but it’s probably not something you’ll use very often, particularly since you should never submerge a phone in salt water if you can help it.

There is also an 8-megapixel front-facing camera which takes standard selfies.

Overall, the camera performance in the Cat S61 is on a par with budget phones like the Moto G6 Plus, and we can’t help feeling it should be a bit better.

Warranty, price, and availability

It costs $1,000 in the U.S. or 800 British pounds in the U.K. and you can buy it directly from the Cat website. It’s available and shipping now.

You get a standard 12-month warranty with the Cat S61 (24 months in the U.K.) which will cover you for any faults.

Our Take

The Cat S61 is clearly not your average phone. It’s a specialist, completely unique, but very expensive digital toolbox that could prove invaluable to the right people. While it is very pricey, you must remember that if you were to buy standalone thermal imaging, laser measurement, and air quality meters you’d be looking at paying out several hundred dollars. The convenience of all this rolled into a rugged phone is going be tempting for some.

Is there a better alternative?

There’s no other phone out there that does what the Cat S61 does. It’s thoughtfully designed with specialist extras that will add real value for some professionals. The closest you’ll find is probably its predecessor – the Cat S60, which is significantly cheaper, but also lacks many of the features that make the S61 so compelling.

There’s no other phone out there that does what the Cat S61 does.

If you just want a rugged phone, then you’ll find some cheaper options, Unihertz Atom or the Doogee S60, as long as you’re willing to import from China. Just don’t expect the same quality as the Cat S61. You might also look at the Galaxy S8 Active, or wait a wee while to see if a Galaxy S9 Active materializes. Check out our guide to the best rugged smartphones for more.

Anyone who just wants a great smartphone with this budget should consider the iPhone X or the Galaxy S9 Plus or wait to see what the next Pixel phone from Google offers. You could also save yourself a significant chunk of change with something like the OnePlus 6.

How long will it last?

In terms of durability, this device could probably serve you for the next five years and beyond – it’s the toughest smartphone we’ve ever used. It’s good that the Bullitt Group has already said the Cat S61 will get upgraded to Android P, but we feel the processor is going to start to feel annoyingly slow within two years.

Should you buy it?

Yes. If you have a genuine use for thermal imaging and the other tools, and you need something tough, the Cat S61 has been designed for you. If you’re just tempted by the novelty, we think you’ll regret the decision because you can get a more powerful phone without the extras for far less.


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