Camera heart-rate check
Covering the camera and flash with a fingertip lets the phone see the colour change of blood pulsing through your finger. Sensor Lab includes this for fun. It is not a medical device.
| Sensor used | Camera with LED flash |
|---|---|
| Unit | Beats per minute (BPM) |
| Useful range | Resting heart rates, with the finger held still |
| Cannot do | Diagnose anything, detect arrhythmia, or substitute for a pulse oximeter or ECG |
The mechanism, not the marketing.
This is photoplethysmography. The flash shines light through your fingertip and the camera watches the light that comes back. Each heartbeat pushes more blood through the tissue, which absorbs slightly more light.
The result is a small rhythmic fluctuation in image brightness. Counting the peaks over time gives beats per minute — the same principle used by the green LEDs on the back of a fitness watch.
What a phone cannot do here.
- The app's own listing is explicit that this tool is for fun and is not a medical device. Do not use it to make any decision about your health.
- It is very sensitive to movement, finger pressure and ambient light. Too hard a press restricts blood flow and the signal disappears.
- It counts pulses only. It cannot say anything about rhythm, blood oxygen or anything else a clinical device measures — an irregular heartbeat may simply produce a wrong number with no indication that anything is amiss.
- If you have any concern about your heart, see a doctor rather than an app.
Is a phone camera heart rate reading accurate?
For a resting pulse with a still finger it can land close to the real figure. It is not reliable enough for anything that matters, and it is not a medical device.
Can it detect an irregular heartbeat?
No. It counts brightness peaks, and an irregular rhythm will simply yield a wrong number. Detecting arrhythmia requires an ECG.
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