Open the HEIC file with an app that supports HEIC (e.g., Photos on macOS, Photos on iOS, or a HEIC-capable viewer)
Use the in-app export option (often “Share” or “Export”) and choose JPG/JPEG as the format
On macOS: Open the HEIC in Preview, then choose File → Export…, select Format: JPEG, and save
On Windows: Install an HEIC extension from Microsoft Store (or a HEIC-capable app), then open the HEIC in Photos and choose Save as / Export as JPG
Use an online converter: upload the HEIC, select JPG output, download the converted file
Use command line (macOS/Linux) with ImageMagick: `magick input.heic output.jpg`
Use command line (Windows) with ImageMagick: `magick input.heic output.jpg`
Batch convert (ImageMagick): `magick mogrify -format jpg *.heic`
Use a dedicated converter app (HEIC to JPG) and convert one or multiple files to JPG output