HEIC (High Efficiency Image Coding) is the default photo format on iPhone and iPad since iOS 11. It produces smaller files than JPEG at equivalent visual quality — a typical iPhone photo in HEIC is around 3-5 MB versus 8-12 MB as JPEG. The trade-off is compatibility: not every device or application can open HEIC natively. Converting to PDF solves this by producing a universally viewable file.
Why HEIC exists
Apple adopted HEIC in 2017 as the default capture format for its camera because the file sizes are roughly half those of equivalent JPEG files. This means twice as many photos fit in the same storage. iOS automatically converts to JPEG when you share a photo to a non-Apple app — but if you transfer the raw file directly (via Finder, AirDrop to Mac, or a USB cable), you get the HEIC original.
HEIC is based on the HEIF container (High Efficiency Image File Format) standardised by MPEG. Apple uses it with the HEVC (H.265) codec for still images.
Browser compatibility
The HEIC to PDF conversion on Filum runs entirely in your browser. It relies on your browser's built-in HEIC decoder — Chrome 118 or later and Safari 16 or later both include one. Firefox does not currently support HEIC natively. If you are on Firefox and the conversion fails, switching to Chrome or Safari will resolve it.
No plugin or extension is required. No app needs to be installed. If your browser supports HEIC, the conversion happens in the page.
On-device processing
The tool runs entirely in your browser. The HEIC file is decoded locally using your browser's built-in HEIC support, the decoded image is embedded into a PDF using pdf-lib (a JavaScript PDF generation library), and the resulting PDF is downloaded to your device. Nothing is uploaded. Your photos never leave your device.
This matters for photos that contain personal or sensitive content. The absence of an upload step removes a category of risk entirely.
Multiple photos
You can select multiple HEIC files at once. Each photo becomes one page in the output PDF. You can reorder the pages before creating the PDF by dragging the rows or using the up and down arrows.
The pages are sized to their image's aspect ratio — portrait iPhone photos produce portrait pages, landscape photos produce landscape pages. Images are scaled down proportionally if they exceed A4 size in points, but they are never stretched or distorted.
Converting HEIC on other platforms
On macOS, Preview can open and export HEIC files natively. On Windows 10 and 11, the HEIC Image Extensions (a free Microsoft Store download) adds HEIC support to Photos and the system image viewer. Neither of these approaches requires an upload either — but the Filum tool is the fastest path to a PDF specifically.
If you need to convert large batches of HEIC photos to PDF, the on-device browser approach scales: you can select many files at once without any upload time constraint.