Cat S61 hands-on review

Brawnier. Brainier. Cat's S61 measures heat, distance, and even air quality

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.


  • Water resistance, tough body
  • Thermal camera has been improved
  • Air quality sensor is clever
  • Surprisingly normal-looking design


  • Expensive

If you don’t remember the Cat S60 phone, it was the world’s first smartphone with a thermal imaging camera on the back. It’s not something most of us would normally use, but the phone turned out to be incredible well-received by tradesmen in industries as varied as plumbers and security guards to vets. This is the Cat S61, the S60’s sequel, and Cat Phone-makers Bullitt Group have listened to the prime customers using or interested in the S60, and integrated three of the most desirable new features into the latest, even more capable device.

Improved thermal sensor

The thermal imaging camera, made by experts Flir, is still present, and while the Lepton sensor is the same as on the S60, the software has been reworked and updated. It’s more user-friendly, but more crucially, the thermal image resolution has increased. The S60’s old VGA image has been replaced by an HD picture, and the difference is dramatic. Now, the display shows considerably more heat spots, with more clarity, making at-a-glance temperature assessment easier and quicker. Additionally, the temperature range has improved as well, starting at -20 degrees centigrade (-4 degrees Fahrenheit) and rising to 400 degrees (752 degrees Fahrenheit), up from 100 degrees centigrade on the S60, making it more versatile.

Wondering what you’d use a thermal imaging camera for? The S61 is helpful for car mechanics, where engine operating temperatures are often much higher than 120 degrees. Vets, especially those that work with horses, have used the camera to identify internal swellings when horseshoes have been incorrectly fitted. The camera’s ability to see hotspots up to 30 meters away has helped security guards out too, as they use the phone to scan areas where their guard dog is barking, without the need to use a flashlight. Greater temperatures and more visual clarity will only increase the device’s usefulness.

More sensors

The first brand new addition to the phone is an air quality sensor. It’s a Volatile Organic Compound sensor (VOC), picking up a range of contaminants and designed for indoor use. It’s tailored for people working with potentially hazardous materials that affect the air in a room, including solvents, cleaning products, paint, or glue. The sensor provides real-time reports and adapts as you move around. The data is presented in clear, color-coded graphs. Additionally, it shows humidity and temperature data in case you need it.

Andy Boxall/Digital Trends

Joining the thermal imaging camera and air quality sensor is a laser distance measure. It’s built into the rear of the phone, and is effective up to 10 meters. It doesn’t just measure straight lines, it can also plot 2D shapes like walls. For example, the laser can measure out a wall space to help estimate the amount of tiles needed to cover it. We didn’t see it working on the prototype of the S61.

Same rugged body

All this is encased in a hard-wearing Cat Phone body, with its IP68 water-resistant rating, and a rugged exterior that goes through extensive tests. For example, Bullitt claims the device withstands drops from up to 1.8 meters in height on to a variety of hard surfaces. The screen measures 5.2-inches and has a 1,920 x 1,080 pixel resolution, is covered in Gorilla Glass 5, and there are three hardware Android buttons under it. The phone’s thick and heavy, which is a consequence of a 4,500mAh battery inside, but it does help improve grip especially if you’re wearing gloves. Also, the aluminum die-cast body is designed to meet MIL-STD-810G military toughness standards, and the screen works even if it’s wet.

The phone itself doesn’t have remarkable specifications, but it does everything you’d want.

Android 8.0 Oreo is kept relatively clutter free, with the only changes instantly obvious coming from extra tools for the thermal camera, and a toolkit-style recommended apps section. Bullitt confirmed it will release an update for this year’s Android P version in the future.

The phone itself doesn’t have remarkable specifications, but it does everything you’d want with a 16-megapixel camera on the rear, and an 8-megapixel camera on the front. Inside is a Snapdragon 630 processor, 4GB RAM, and 64GB storage space. This gives the S61 an acceptable level of performance, and it slid through menus smoothly enough; but response times for apps was slow. We used a prototype phone, so it’s unfair to judge performance without further testing on a final unit.

Price and availability

Given what makes the Cat S61 special, it’s clear the phone is designed with specific use cases in mind. Anyone looking at a Samsung Galaxy S9 likely won’t be considering a Cat S61, but if you have considered a Galaxy S8 Active, then the Cat S61 may be a great alternative.

Sadly, you’re going to have to pay a premium for all this tech — the Cat S61 will cost 800 British pounds or about $1,117 when it goes on sale in the next few months. There are no plans yet to bring the phone into the U.S. Still, when you add up the individual costs of a tough phone, a thermal imaging camera, an air quality sensor, and a laser distance measure, the Cat S61’s may just be worth the high cost.