REVIEW: Cat S61 boasts better thermal camera, new laser measuring. But can it all justify the $1k price tag?

The Cat S60 represented a turning point for the Caterpillar brand’s smartphone partnership with U.K.-based device maker Bullitt Group. After releasing a few variations on the same theme—affordable Android phones with military grade durability—Bullitt produced a device in the S60 that sought to explore what might happen if you designed a phone that doubled as a gadget for construction work.

As I noted in my review of the S60 back in 2016, it had character to it. One look at the S60’s chunky design, waterproofing valves (complete with gold switches on the face of the phone), and the distinct FLIR branding for the integrated thermal camera, and you knew this wasn’t just another black rectangle from Apple or Samsung.

It was unique in the sense that it was a phone built to assist with and survive jobs done on a worksite. And though Cat and Bullitt don’t divulge phone sales numbers, the S60 must have resonated well enough both with customers and within the companies that produced it, that a successor to that device has been introduced: the S61.

Bullitt Group spokesperson Carla Richardson says that in the two years since the S60’s introduction, her company and Cat have gathered “an incredible amount” of customer feedback on that device. She says the two companies funneled all of that information, provided by more than 20,000 surveyed customers, into the development of the S61.

How does the S61 build upon the foundation laid by the S60? Read on to find out.


Though we’re dealing with a new phone, the S61’s most interesting feature remains the integrated FLIR thermal imaging camera introduced on its predecessor.

Through its customer surveys, Cat and Bullitt found that 60 percent of S60 users used the phone’s thermal camera at least once per week. Richardson says when asked how to improve the FLIR camera, customers asked for the ability to read higher thermal points.

Bullitt listened and now the S61 can provide readings up to 752 degrees Fahrenheit, up from 250 degrees on the S60. The FLIR camera’s software has also been upgraded to provide better image contrast. These changes, Bullitt says, should come in handy particularly for road crews when monitoring asphalt.

In my use, I can certainly see the difference, especially with the improved images the FLIR camera provides on the S61. Differences in thermal regions are more distinct and because the image of the underlying surface you’re measuring are improved, the camera is much more valuable this time around.

The photo above was taken in very low light. The image the FLIR camera produced isn’t quite night vision, but it did provide more visible detail than I saw with my eyes. Richardson adds that the new camera allows users to do perform straight averages, area averages or spot temperature measurements, which should be of use to mechanics and HVAC technicians.

You can also live stream from the thermal camera to YouTube should you need to share what you’re seeing with a colleague in real time.

Perhaps as a result of the software improvements, the FLIR camera seems to load a bit faster than it did on the S60. All in all, this remains an impressive and well thought out exclusive feature of the S61 and one that should continue to be an attractive selling point to anyone in the trades looking to get more practical use out of their smartphone while on the job.

As far as the S61’s other cameras go, these remain a weak point for Cat-branded smartphones.

Though Bullitt upped the S61’s rear camera to 16 megapixels from the S60’s 13, the quality remains below average for a modern smartphone camera. Though its serviceable in well-lit situations, the S61’s camera produces grainy and often blurry photos. In fact, having too much light, such as being outdoors on a sunny day, can cause the camera trouble as photos tend to be blown out pretty easily and you can lose detail in the highlights if you’re not paying close attention to what the camera is focusing on.

The S61’s color reproduction is admirable, if not a bit oversaturated. But once you zoom in on the details of your subject, the flower in this instance, the details are soft and disappointing.

That being said, after taking a look at photos shot in several situations, the S61 holds what is probably the best camera and image sensor combo Bullitt has placed inside a Cat phone. Yes, some of the details can be a bit soft and low light photos quickly fall apart into a grainy mess (forget snapping a picture of a moving kid indoors), but the camera does an OK job in average situations and actually produces photos that are a huge improvement over what the S60 and other previous Cat phones produced.

Another update to the S61’s camera is the ability to shoot 4K video. Unfortunately, I found little reason to use this setting. Unless you’ve got a 4K TV or computer display to play the resulting videos on, I’d keep the S61 shooting in 1080p.

For starters, the file sizes are much smaller and take up far less room on the phone’s 60 gigabytes of internal storage. Second, if you’re thinking of using the S61 to shoot video for work, trust me when I say that that the quality of 4K video this phone produces isn’t quite something you’d want to feature in a professional setting or project. I found the S61’s 4K videos to be semi-sharp, with much of the detail you’d expect to be gaining from such a high-resolution video lost to soft lines. Plus, because there is no digital or in-lens camera stabilization at work in the S61, 4K videos tend to have more jiggle than a bowl of Jello. Any kind of movement makes them hard to watch.

As far as the front facing camera goes, the 8MP camera on the front of the device is one of the oddest selfie cameras I’ve ever encountered. There seems to be something weird going on with the software or the image sensor because the images it produces seem to have the sharpness setting turned up to 100. Any picture I took of myself resulted in a very unpleasant, craggy and shiny look to my skin with the outlines and other details in my face being rendered with a lot of contrast. It almost looks like one of those filters that’s supposed to mimic how drawings look. It’s also pretty awful in low light.

New features

Cat and Bullitt didn’t stop with updates to the cameras in the development of the S61. Thankfully, the two partners saw the success in the S60 as inspiration to add more gadgety features for those in the trades.

First among these is laser distance measuring. Unlike the augmented reality-based measuring system soon to be released by Apple in iOS 12, Bullitt has integrated an honest-to-God Class 2 laser into the back of the S61 for making point-to-point measurements up to 10 meters (32.8 feet). The system can also calculate area and switch between Metric and Imperial measurements.

The S61 emits a laser dot from the back of the device near the bottom.

The system works by using the laser to place a red dot on the surface you’re measuring to, and then snapping a picture of that dot using the non-thermal rear camera. Based on that dot in the image taken by the camera, the custom app on the S61 that hosts this functionality can give you a rough estimate of the distance between the phone and surface.

When you open the measuring app on the S61 you’re first taken through an initial setup and calibration between the camera and laser that is a bit wonky and involves putting the phone on table with enough hanging off that the laser dot can find its way to the floor. But once it’s calibrated, I found the app to be fairly accurate. Richardson told me that the measurements provided are intended to only serve as estimates, but I found them to usually fall within a few inches of the actual distance. All in all, it’s a nifty feature that could actually save you some time on those measurements that don’t depend on extreme precision.

The second new feature is a built-in air quality sensor. This Sensirion sensor can work in the background on the phone and alert you when your working environment has high levels of indoor air pollutants (Volatile Organic Compounds or VOCs). Cat and Bullitt say sources of VOCs can include paints, solvents, carpets, furniture and cleaning products. The sensor also provides humidity and temperature readings.

I didn’t have an opportunity or suitable environment to do in-depth testing with this feature in my time with the S61, but the humidity readings look to be pretty accurate and I did notice the sensor note less than optimal air quality when using cleaning products around the house.

Who knows how many S61 users will get regular use out of these new features, but I love that Bullitt is actively trying to develop smartphone features aimed squarely at the trades. As Richardson said during our talk about the S61, the smartphone should be a Swiss army knife while on the job. She notes that Bullitt is trying to build phones that are seen by its users as “one of the most important tools in their toolbox.” Developing more integrated features like these is the right way to go about it.

Here are a few more feature notes on the S61, including a couple of Android-specific features:

  • Now Android Pay capable
  • Can activate the Google Assistant by saying “OK Google”
  • Sand, dirt, dust resistant
  • Integrated FM radio
  • 64GB internal storage, expandable via microSD
  • Dual sim card slots


With each phone Cat and Bullitt release, the overall device design has improved. Because they are designed to survive drops, dirt and water, Cat Phones have always boasted a solid construction and a nice heft to them, but there have been noticeable improvements to the fit and finish of these phones over the years that must be pointed out and appreciated.

The S61 houses its 1080p screen inside a frame incorporating a rubberized back and aluminum sides. They give the phone the look and feel of a premium smartphone– and they should. At $999, the S61 represents nearly a $400 premium over its predecessor the S60.

Along with the updated look and feel, the S61 also boasts more rugged credentials than its predecessor. It’s one of the first phones to receive an IP69 rating for its high-pressure waterproofing. Not only can the phone be submerged in up to 9.8 feet of water for up to 1 hour, it can even keep water out when being blasted by a pressure washer, Richardson says.

The device also boasts a MIL Spec 810G rating and is able to withstand drops to concrete from up to 6 feet.

A couple of other notes on the design of the S61:

  • The physical front buttons have been improved over those on the S60. The S60 had a texturized surface on these buttons. That texture has been removed in favor of a smooth finish that’s more pleasant to handle. These new buttons also have a better feel when pressed.
  • Bullitt has made the switch to USB-C on the charging and data port on the S61.


When it comes to the computing speed on the S61, though Bullitt has beefed up the phone’s internals, things unfortunately remain a decidedly mixed bag in terms of performance.

The S61 features a Qualcomm SD630 2.2GHz, eight-core processor. Though the device ships with Android version 8, a.k.a. Oreo, Richardson says this chip was chosen in order to provide enough processing power so that the phone could be upgraded to the latest version 9, dubbed Pie.

And while the effort to keep updates coming into the phone is appreciated, the processor is disappointing. When tested under load through the Geek Bench CPU testing app, the S61’s processor scored an 882 on the single-core test, which measures performance during typical light load tasks like email, texting and the like. That score ranks the S61 lower than the Samsung Galaxy S5, a four-year-old phone.

Things were a bit better in the multi-core results, which test more intensive processor tasks. In this test the S61 scored a 4243 which places it above the original Google Pixel, but still worse than the Samsung Galaxy S7, which are both two-year-old devices.

I also tested performance with the AnTuTu Benchmark app. AnTuTu ranks the S61 in the bottom 30 percent of all smartphones for CPU performance, the bottom 20 percent in GPU performance and the bottom 50 percent in memory speed.

In other words, when it comes to pure speed and performance, the S61 is a below average device. That’s not a pretty picture, but don’t get me wrong. I don’t say all of this to suggest that using the device is nothing but slowdowns and crashes.

Yes, if you’re used to the speed of an iPhone or a newer Android device like the Samsung Galaxy S8, you’re going to feel the lesser performance the S61 offers. Most operations, like switching in and out of apps and paging through home screens are fairly snappy. But social media apps, games and other apps that can tax memory and the GPU do produce regular slowdowns. I encountered most of these slowdowns when opening or closing the camera and FLIR apps and quite a few while using Instagram.


Easily the most impressive feature about the S61 is its battery. Bullitt has included a massive 4500mAh monster in this device that the company says provides up to 37 days standby time and 35 hours of talk time.

I tested the battery with Geek Bench, which puts the phone under a heavy load and prevents the device from sleeping while keeping the screen at around 70 percent brightness. With all of that going on, it still took more than 11 hours to kill the S61. That’s flat out impressive. S61 users will never have to worry about this device dying on them.

And when you do need to charge up the phone, Bullitt has added Quick Charge 4.0 capability and has swapped the micro USB charging and data port on the S60 for a new USB-C port on the S61. The result is a phone that not only lasts a really long time between charges, but also charges faster.


As I noted before, Cat and Bullitt have made great, iterative gains in design and features with each generation of rugged smartphone the partnership has produced. However, these phones are also getting more expensive with each passing year.

With the launch of the B15, the aim seemed to be to create a $500-ish phone with serious rugged credentials at a price point that didn’t require a two-year contract. But with the release of the S61, the price has nearly doubled to $1,000.

Of course, this phone has a bigger, better screen, a ton of battery life, and built-in thermal imaging, laser measuring and air quality monitoring. The ability to update it to Android P is also a nice consideration on Bullitt’s part. However, as was the case on the S60 before it, the processor and non-thermal camera are still major deficiencies on the S61. In the end, it’s hard for me to recommend a $1,000 device when you can’t wholeheartedly stand behind its ability to push through everyday tasks like switching between memory-intensive apps or taking a photo of your kid that’s not one big blur.

In the past, you might have suggested using a Cat phone for work and an iPhone for home but the cost now prevents that type of recommendation. I applaud Bullitt for leaning into the niche aspects of the S61. The goal of Cat Phones shouldn’t be to compete with giants like Apple and Samsung. But that also means not pricing your devices like Apple and Samsung phones. And if you do, it means making sure core elements like the device’s camera and CPU aren’t noticeably worse than phones at the same price point.

If Cat and Bullitt decide to stick with this $1,000 price point, their next phone needs to take meaningful strides in performance and image quality.