Looking for a FLIR ONE alternative?
FLIR ONE is the best-known phone thermal camera, and for good reason. But it isn't the only way to put a thermal camera on a USB-C iPhone or Android phone. Here's how it compares with Spark and Spark Pro — including the things FLIR does better.
The FLIR ONE family today
FLIR currently lists four phone cameras. Two plug into the phone and two are separate handheld units that talk to the phone over Wi-Fi:
- FLIR ONE (formerly FLIR ONE Gen 3) — plug-in, 80×60 thermal sensor.
- FLIR ONE Pro — plug-in, 160×120 thermal sensor.
- FLIR ONE Edge — wireless, 80×60.
- FLIR ONE Edge Pro — wireless, 160×120.
Spark and Spark Pro are plug-in cameras, so the fair comparison is FLIR ONE against Spark, and FLIR ONE Pro against Spark Pro. The wireless Edge models are covered further down.
FLIR ONE vs Spark
| FLIR ONE | Spark | |
|---|---|---|
| Thermal sensor | 80×60 (4,800 readings) | 96×96 (9,216 readings) |
| Refresh rate | 8.7 Hz | 25 Hz |
| Temperature range | −20 to 120 °C (−4 to 248 °F) | −20 to 400 °C (−4 to 752 °F) |
| Field of view | 50° × 38° | 50° |
| Visible camera (MSX) | Yes | No |
| Battery | its own, about 1 hour per charge | — |
| Weight | 36.3 g | 19 g |
| Plug | Lightning or USB-C (separate versions) | USB-C |
FLIR ONE Pro vs Spark Pro
| FLIR ONE Pro | Spark Pro | |
|---|---|---|
| Thermal sensor | 160×120 (19,200 readings) | 256×192 (49,152 readings) |
| Refresh rate | 8.7 Hz | 25 Hz |
| Thermal sensitivity | 70 mK | 50 mK |
| Temperature range | −20 to 400 °C (−4 to 752 °F) | −20 to 350 °C (−4 to 662 °F) |
| Field of view | 50° × 43° | 50° × 37.5° |
| Visible camera (MSX) | Yes | No |
| Battery | its own, about 1 hour per charge | — |
| Weight | 36.5 g | about 21 g |
| Plug | Lightning or USB-C (separate versions) | USB-C |
Each thermal pixel is one temperature reading. Spark Pro takes about two and a half times as many as FLIR ONE Pro, and it refreshes the picture 25 times a second instead of 8.7, so the image stays smooth while you sweep it along a wall.
Where FLIR ONE is the better choice
- MSX. FLIR ONE has a second, ordinary camera and draws its outlines — window frames, outlet covers, the edge of a cabinet — on top of the thermal image. That makes a picture much easier to read, and to show someone else. Spark and Spark Pro show the thermal image only.
- Older iPhones. FLIR ONE and FLIR ONE Pro come in a Lightning version. Ours are USB-C only, so they won't fit iPhone 14 or older.
- Hot work. FLIR ONE Pro measures up to 400 °C, Spark Pro to 350 °C.
- Away from the phone. FLIR ONE Edge and Edge Pro work without being plugged in — up to 5 m (16 ft) away over Wi-Fi — and are rated IP54 and for a 2 m (6.5 ft) drop. They are larger units, about 153 g. Spark and Spark Pro have to be plugged into the phone.
- Reports. FLIR lists its own software, FLIR Ignite and FLIR Thermal Studio, alongside the FLIR ONE app.
Where Spark and Spark Pro are the better choice
- More detail. Spark has more thermal pixels than FLIR ONE, and Spark Pro more than FLIR ONE Pro.
- Smoother picture. 25 Hz instead of 8.7 Hz.
- Lighter on the phone. 19 g and about 21 g, against about 36 g for the plug-in FLIR ONE models.
- Range on the small one. Spark reads up to 400 °C; FLIR ONE stops at 120 °C, which rules out things like a stovetop, a flue or an exhaust.
- One plug for iPhone and Android. The same camera works on a USB-C iPhone and on Android 12 or newer, with the free THG Start app.
From us, both come with free tracked shipping (usually 7–19 business days) and 30-day returns.
So which one?
If the visible-light overlay matters to you, or your iPhone still has Lightning, FLIR ONE is the right camera. If you want the most thermal detail and a smooth picture on a USB-C phone, choose Spark Pro; for close checks — a window frame, a breaker panel, a charger — Spark is enough. More on fit: thermal cameras for iPhone 15, 16 and 17.
FLIR and FLIR ONE are trademarks of their owner; we're not affiliated with FLIR. FLIR specs are from FLIR's own product pages as of October 2026.
