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Heart-Rate Monitor Tester

Check your strap pairs, transmits and reports good contact. Not a medical measurement.

How this talks to your device

The page connects to the standard Heart Rate service, subscribes to its measurement characteristic, and shows what the strap sends. The packet format is published, and parsing it exactly is what makes this reliable: a flags byte selects whether the rate is 8-bit or 16-bit, whether energy expended follows, and whether beat-to-beat intervals follow that — so an assumption about any one field shifts every value after it. Sensor contact is encoded as two separate bits, supported and detected, and conflating them either invents a warning or hides a real one. Beat-to-beat intervals arrive in units of a 1024th of a second rather than milliseconds, which is a 2.4% error if taken at face value. What the page then reports is about the equipment: whether the pairing worked, whether notifications arrive at a steady rate, and whether the strap says its electrodes are making contact. It gives no verdict about the heart rate, because that is not something this or any web page should do.

What the results mean

Sensor contact
The strap's own report of whether its electrodes are against skin. This is the useful diagnostic — dry pads are the most common reason a strap works for ten minutes and then drops out, and wetting them fixes it in seconds.
Update rate
How often notifications arrive. Most straps send about once a second; long or irregular gaps point at a struggling radio link, a weak battery, or interference.
Beat-to-beat intervals
RR intervals, where the strap sends them, converted from the specification's 1024ths of a second into milliseconds. Simpler straps omit them entirely, which is normal.
Latest reading
What the strap transmitted, shown without any judgement attached. It is not a medical measurement and carries no pass or fail on this page.

Common problems and fixes

The strap connects then reports poor contact
Wet the electrode pads. A dry strap is by far the most common cause, the flag exists in the specification precisely because of it, and water resolves it immediately.
The strap does not appear in the chooser
Only devices advertising the standard Heart Rate service are listed. Check it is switched on, worn or damp enough to wake, and not already connected to a phone or watch — most straps accept one connection at a time.
Readings arrive but stop after a minute
That pattern is contact or battery. Check the contact status shown here while it is happening, and replace the cell if the strap is more than a year into use — a weak battery produces a link that connects and then transmits erratically rather than failing outright.
The strap works with its own app but not here
Some manufacturers use a proprietary protocol instead of, or alongside, the standard service. Where the standard service is absent, no general-purpose tool can read it — the app can only because it was written for that device.

Frequently asked questions

Can I use this to check my heart rate?

No. This is an equipment test and nothing on the page is a medical measurement or a health assessment. It exists to answer whether a strap pairs, transmits steadily and reports good contact. Any question about what a heart rate means belongs with a qualified professional and appropriate equipment, not with a web page reading a consumer device over a radio link.

Why does the page show a number but no verdict about it?

Deliberately. Showing the value proves the strap is transmitting, which is the point of the test. Banding it as good or bad would be a health judgement, and this tool is not equipped to make one — a strap on a person who has just climbed stairs and a strap on a person sitting still produce very different numbers, both of them fine.

Is my heart-rate data being stored?

No. The values appear on screen while you watch and are held only in the page. The exportable summary carries connection statistics — how many notifications arrived, at what interval, and what the contact flag said — and deliberately contains no heart-rate values at all, because those are body data and do not belong in an export.

Why do some straps report beat-to-beat intervals and others not?

It is optional in the specification. Straps aimed at training analysis usually send them because the variability between beats is what those applications work from; simpler straps send only the rate. Neither is a fault, and this page reports which one you have rather than treating the absence as a problem.

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