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testo 860i Review: Compact App-Connected Thermal Imaging

The testo 860i is testo's answer to phone-attached thermal cameras: a standalone 256×192 imager that connects wirelessly to iOS or Android and can be clipped to the phone or used one-handed. This review covers the detector, the radiometric app tools, the build and how it compares with FLIR and TOPDON alternatives.

By the Akermin Editorial Team · 4 min read

As an Amazon Associate, Akermin earns from qualifying purchases. Product links on this page are affiliate links.

testo 860i Review: Compact App-Connected Thermal Imaging

Testo · testo 860i Wireless Thermal Imaging Camera Set for iPhone & Android - Thermal Imager with Carrying Pouch & USB-C Cable - Handheld Infrared Camera 256 x 192 Resolution & -4 to +662 °F Measurement Range

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Price and availability are shown on Amazon and can change at any time.

Verdict

The testo 860i occupies a space that neither phone-plug cameras nor traditional handhelds fill well. It has a 256×192 detector (49,152 pixels), a measurement range of -20 °C to 350 °C (-4 °F to 662 °F), full radiometric images and a professional analysis app, but instead of plugging into the phone it streams over Bluetooth and Wi-Fi and can be clipped to the phone or held in the other hand. The body is IP54 rated and drop-protected to 5 ft. That combination suits technicians who already use testo Smart Probes and want thermal images in the same app and reports. It costs more than a TOPDON plug-in with the same detector; what you pay for is the wireless design, the radiometric workflow and testo’s documentation standard.

Who It Is For

  • HVAC and refrigeration technicians who already run testo Smart Probes and want thermal images in the same report.
  • Electricians who want to hold the camera at a panel while the phone stays back.
  • Building inspectors who want radiometric files without carrying a full-size handheld.

It is less compelling for a homeowner who wants a one-off look at insulation; a plug-in TOPDON or FLIR ONE is cheaper for that. Our guide to choosing a smartphone thermal camera compares the formats.

Documented Specifications

Item Documentation
Thermal detector 256×192 (49,152 pixels)
Measurement range -20 °C to 350 °C (-4 °F to 662 °F)
Measurement Full radiometric
Analysis functions DeltaT, DeltaHeat, DeltaCool
Connectivity Bluetooth and Wi-Fi to the testo Smart App (iOS 17+, Android 14+, Bluetooth 4.0)
Handling One-handed or clipped to a phone or tablet
Protection IP54; fall protection to 5 ft
Set contents Camera, carrying pouch, USB-C cable

Why Wireless Changes the Job

A plug-in camera makes the phone the camera body: it has to be pointed at the target, which means the technician’s hand and phone are at the panel or in the ceiling void. The 860i separates the two. The camera can be clipped to the phone for ordinary use, or unclipped and held into a cabinet, over a duct or under a vehicle while the phone shows the live image from a comfortable position. The same idea appears in the FLIR Edge Pro. The trade-off is that the 860i has its own battery to charge over USB-C, and pairing adds a step compared with plugging in.

Detector and Radiometric Measurement

At 256×192 the detector matches the TOPDON TC-series and exceeds the 160×120 FLIR ONE Pro and Edge Pro. The range to 350 °C covers HVAC, electrical and most mechanical work. Radiometric capture is the professional feature: the saved image holds a temperature for every pixel, so the analysis can be redone later, a spot moved, an area drawn, or a DeltaT reported between two points that were not marked on site. The DeltaHeat and DeltaCool functions colourise pixels above or below a threshold, which turns a thermal image into a quick pass/fail picture for heat loss or a cooling fault. For emissivity handling on metal, see how to set emissivity on a thermal camera.

App and Reporting

The testo Smart App is the same app used by testo’s Bluetooth probes, so a refrigeration technician can have superheat from a pressure probe, air temperature from a 605i and a thermal image of the coil in one report. Reports are generated on the phone as PDF or CSV and can be shared directly. Owners of other testo Smart Probes describe this as the reason to choose the 860i over a cheaper camera with a separate app. For a first-time thermal buyer with no other testo equipment, the advantage is smaller.

Build and Field Use

IP54 means dust-protected and splash-resistant, which is adequate for plant rooms and roof spaces but not for washdown. The 5 ft drop protection is in line with FLIR’s ONE series. The set includes a pouch and a USB-C cable. There is no built-in visible camera on the 860i; documentation photos come from the phone.

Strengths

  • 256×192 detector with full radiometric images.
  • Wireless: camera and phone can be in different places.
  • Integrated with testo Smart Probes and their reporting.
  • IP54 and drop protection.

Limitations

  • Own battery to charge; pairing step before use.
  • Higher price than plug-in cameras with the same detector.
  • Requires a recent phone OS (iOS 17 or Android 14 and later).

How It Compares

The FLIR Edge Pro is the closest concept with a 160×120 detector and MSX. The TOPDON TS001 offers the same detector size with adjustable focus on a cable for Android. The testo 868s is the handheld with 160×120 and a built-in 5 MP camera for those who want a traditional pistol grip. Choose the 860i when wireless handling and testo’s reporting matter more than pixel count per unit of price.

How We Research

This review is based on testo’s published specifications, the Amazon listing for the 860i set and owner reports. We did not run laboratory tests.

Testo 868s Thermal Imager – High-Resolution Thermal Camera with 160 x 120 px - Integrated 5 MP Camera and App-Operation – Thermal Images with Automatic Hot and Cold Spot Detection

Testo 868s Thermal Imager – High-Resolution Thermal Camera with 160

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Flir Edge Pro Wireless Thermal Imaging Camera, iOS/Android, 480x360

Flir Edge Pro Wireless Thermal Imaging Camera, iOS/Android, 480x360

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TOPDON TC002C Duo Thermal Imaging Camera for Any USB-C iPhone iPad Android

TOPDON TC002C Duo Thermal Imaging Camera for Any USB-C iPhone

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Products shown because their documented specifications fit this guide. Price and availability are on Amazon and can change.

Frequently Asked Questions

Does the testo 860i plug into the phone?

No. It connects over Bluetooth and Wi-Fi to the testo Smart App and can be clipped to the phone or held separately. The listing states it requires iOS 17 or later, Android 14 or later and Bluetooth 4.0.

Is the image radiometric?

Yes. The listing states full radiometric measurement, which means every pixel carries a temperature that can be analysed after capture.

What are DeltaT, DeltaHeat and DeltaCool?

testo analysis functions in the app: DeltaT shows the difference between two points, and DeltaHeat and DeltaCool highlight areas above or below a reference, which is useful for finding heat loss or cooling faults.

How rugged is it?

The listing states IP54 dust and splash protection and fall protection up to 5 ft.

Affiliate disclosure: Akermin earns a commission from qualifying Amazon purchases made through links on this page. Our editorial picks are based on documented specifications and owner feedback, not commissions.