Buying
Thermal camera apps for iPhone, compared
iPhone thermal camera apps fall into two groups — companion apps for a clip-on sensor, and live camera effects. Knowing which you are downloading saves a lot of disappointment.
Updated
Search the App Store for “thermal camera” and you get a few hundred results. They are not all the same kind of thing, and the reviews are full of people who found that out after paying.
There are exactly two categories. Everything else is a variation.
1. Companion apps for real hardware
These do nothing on their own. Plug the sensor in and they become the screen, the storage and the analysis tool for it.
- FLIR One — for the FLIR One Gen 3 and Edge Pro. 160×120 thermal, spot temperature, MSX edge detail from the visible camera.
- Seek Thermal — for the Compact (206×156) and CompactPRO (320×240). Strong on building inspection features.
- Topdon TCView / InfiRay — for the cheaper TC001, TS001 and P2 Pro modules.
Use these if you need a number you can put in a report. They read actual temperature because there is an actual microbolometer in your hand. Expect to pay for the hardware, not the app.
2. Live camera effects
No extra hardware. The app takes the ordinary camera picture, reads its brightness, and maps that onto a thermal palette — so bright reads as hot, dark reads as cold. Some add a HUD, edge detail, night-vision tints, video recording.
Use these if you want the look: photos and video with iron, rainbow or arctic palettes, night-vision and FX treatments, a heat-camera aesthetic for a video or a costume or a joke. They do not measure anything, and the honest ones say so on the listing.
How to tell them apart before you download
Read the App Store description, not the screenshots. Specifically:
- Does it name a temperature? A simulated app that shows “36.4 °C” on a face in its screenshots is inventing numbers. This is the single clearest tell.
- Does it name the hardware? Companion apps list the exact modules they support in the first paragraph. If no module is named, no module is supported.
- What do the one-star reviews say? For simulated apps they say “it doesn’t work, it’s just a filter” — which means it is a filter and the listing did not make that clear enough.
- Is there a free tier you can see before paying? Anything that puts a full-screen subscription wall in front of the camera before you have seen a single frame is optimising for the wrong thing.
Where ours sits
Thermal Camera: Heat Sensor FX is firmly in the second category and says so everywhere: twenty looks — eight thermal palettes, five night-vision treatments, seven FX — rendered live on the device, with a HUD that marks the hottest and coldest regions of the frame, an MSX-style detail overlay to keep edges readable, an intensity slider, video with sound, and a shutter on Apple Watch. The plain camera and the gallery are free; the effects are the Pro subscription.
What it does not do is read temperature, because your iPhone cannot. If that is what you need, buy a Seek or a FLIR One and use their app.
A quick decision
- You need a number for a report → clip-on sensor + its own app.
- You want to find a draught in your house once → borrow or hire a thermal camera; a phone app will mislead you.
- You want the look, for photos, video or fun → a live-effect app, and pick one whose listing is honest about what it is.