Sync problems here are nearly always the connection rather than the band, and the fixes have a clear order. Work down the list; most people stop at step two.
- 1
Confirm the app has Bluetooth permission
Not whether Bluetooth is switched on. Whether the WHOOP app is allowed to use it. On iOS: Settings, scroll to WHOOP, check Bluetooth is enabled. On Android it sits under app permissions.
This is the most common cause and the least obvious, because the app does not always say clearly that this is why it is failing.
- 2
Force-quit the app and reopen it
Swipe it away entirely rather than just backgrounding it, then reopen with the band on your wrist and the phone close by. This re-establishes the Bluetooth link, which is usually all that is wrong.
- 3
Check the band is charged and on your wrist
A band on the charger or flat will not sync. A band in a drawer across the house is out of Bluetooth range, which is shorter in practice than the specification suggests, particularly through walls.
- 4
Restart the phone
Unglamorous, and it clears the Bluetooth stack problems that cause a surprising share of these. Worth doing before anything more invasive.
- 5
Allow background app refresh
If your complaint is gaps rather than a total failure, this is the cause. Both iOS and Android suspend background apps aggressively. Enable background refresh for WHOOP, and open the app once a day anyway.
- 6
Only now, re-pair or reinstall
Reinstalling resets your permissions and pairing, so you will be redoing steps 1 and 5 afterwards. It genuinely fixes very little that the earlier steps do not.
When it is actually the hardware
Rare, and worth recognising. If the band will not connect to a second phone either, if it does not respond to being placed on the charger, or if it drains from full in under a day, that is a hardware conversation with WHOOP support rather than a settings problem.
Before you start that conversation, request a data export while things still work, because a support process can end in a replacement band and you want your history independent of that: how to export your WHOOP data.
If this keeps happening
Persistent sync friction is one of the more common reasons people eventually stop wearing a device, and it is worth being honest with yourself about whether you are still getting value out of a membership you are troubleshooting monthly.
Worth reading is WHOOP worth it if you are at that point, rather than renewing out of inertia.