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ModelForerunner 255 / 255S

Garmin Forerunner 255 GPS Running Watch manual

A GPS running watch in two sizes, with the Music versions adding storage for songs. Freezes and sync problems are the usual reasons people look for the manual.

Updated Sep 11, 2026 Based on Garmin documentation 2 quick answers Official PDF, 5.8 MB
GPS running watch
ModelForerunner 255 / 255S

01 Quick answers

Factory reset

Restart a frozen watch

Garmin's manual warns that restarting the watch may erase data or settings, so sync with Garmin Connect first if you can.

  1. Hold the LIGHT button (top left) for 15 seconds.
  2. The watch turns off.
  3. Hold LIGHT for one second to turn the watch back on.
Factory reset

Reset all settings

Sync with Garmin Connect first, then open settings, System, Reset. Reset Default Settings restores factory settings but keeps your activity history. Delete Data and Reset Settings wipes settings and history. If you use Garmin Pay, the second option also deletes the wallet.

02 Full PDF manual

The complete official document. Zoom, jump to a page, go fullscreen, download or print it.

Forerunner 255 series owner's manual
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Official document published by Garmin (5.8 MB). Original source: www8.garmin.com. Hosted here for easier reading, and removed on request under our copyright policy.

03 Finding the model number

On the watch, open settings, then System, then About. The back of the case also has the model printed in small text.

Model number guide for other products

04 Specifications

Case sizes46 mm (255) and 41 mm (255S)
Water rating5 ATM
Music storageMusic versions only
SatellitesMulti-band GNSS

Specifications can vary by region and production year. The rating label on the product is the final word.

05 What's in the Garmin manual

The official owner's manual is organized into these main sections. Use the page box in the viewer above to jump between them.

  1. 01Introduction
  2. 02Activities and apps
  3. 03Training
  4. 04History
  5. 05Appearance customization
  6. 06Sensors and accessories
  7. 07Settings
  8. 08Device information
  9. 09Troubleshooting

06 Owner questions

Why won't my watch sync with my phone?

Close and reopen Garmin Connect, check Bluetooth is on, and restart both the watch and the phone. Remove and re-pair only as a last step.

Can I swim with it?

Yes. The 5 ATM rating is suitable for swimming, and there are pool and open water swim modes.