Beatcast
EN

Garmin HRM-Dual with iPhone

Updated

Short answer

The Garmin HRM-Dual sends heart rate over ANT+ and Bluetooth. An iPhone has no ANT+ radio, so it hears the Bluetooth side, and any app that reads the standard Bluetooth heart rate service can use it. Wake it by wearing it with damp contacts, then pick it in the app.

Last checked: 12 October 2026.

What works, and what to expect

  • Works: live heart rate over Bluetooth in an app that reads the standard service. That is how the HRM-Dual sends it.
  • Won't work: the ANT+ side, on any iPhone.
  • Depends: how many things can listen at once. Garmin has said two Bluetooth connections plus ANT+ (details below).

Connections

DC Rainmaker's in-depth review first said the strap allowed one Bluetooth connection at a time, like most Bluetooth straps. He then added an update: Garmin had told him it misspoke, and the HRM-Dual supports two concurrent Bluetooth connections plus unlimited ANT+ connections. He says he checked it with an iPad, an iPhone and a watch over ANT+.

That review dates from 2019. Treat two as the number to try. A watch on ANT+ takes no Bluetooth slot, which is why a Garmin watch and a phone can share one strap.

Why it reads zero or drops

The forums fill up with the same few causes:

  1. The strap is dry. Moisten the contacts and wear it snugly.
  2. Something else has both Bluetooth slots. Close other apps and check any bike computer or trainer.
  3. The battery is low. It uses a CR2032 coin cell, and Garmin's listing quotes years of use at an hour a day, so a dead one usually means an old strap.
  4. The app is looking for ANT+. Nothing on an iPhone will find it that way.

The not connecting checklist takes these in order.

Pair it in the app

You pick the strap in the app's own sensor list, and Beatcast connects with no bonding and no allow-list. Allow Bluetooth when asked, wear the strap, open the list.

What Beatcast does with it

The number goes to the Dynamic Island and the Lock Screen while a session runs, stays on while you are in another app, and fills the screen in zone colour when you prop the phone up. The session is kept with time in zone and exports as CSV or TCX.

Beatcast on the App Store. Fourteen days free, then one purchase.

Questions

Is the HRM-Dual the same as the HRM-Pro?

They are different straps. The HRM-Pro is also on the sensor list.

Can I use it with Zwift and Beatcast together?

If the strap accepts two Bluetooth connections, yes in principle. Check the connections table.

Will my Garmin watch still get it?

Over ANT+, yes, per Garmin.

See also: Garmin HRM 600, Garmin HRM-Pro Plus, ANT+ and the iPhone.

Good to know

Beatcast is not a medical device. It is built for training and general wellbeing, and it cannot detect, diagnose, treat or monitor any condition. If something about your heart worries you, talk to a doctor rather than to an app.

The Bluetooth word mark is a registered trademark of Bluetooth SIG, Inc. Apple, iPhone, iPad, Apple Watch, Dynamic Island and Lock Screen are trademarks of Apple Inc. Garmin, Zwift and other names belong to their owners and are used only to say which sensors Beatcast can read. Beatcast is an independent product and is not affiliated with, endorsed by or certified by any of them.

Got yours working? Report it in r/beatcast and it goes on the list.