Convert HEIC to PDF

Why this conversion exists at all

Almost nobody wants a PDF of their holiday photos. The people who search for this have taken pictures of something with an iPhone — a lease, a set of receipts, a signed form, a passport page, a doctor's letter — and the other end will only accept PDF. Sometimes it is a portal that rejects images outright; sometimes it is a person who wants one attachment instead of eleven.

So this page is built around that job. Multiple photos become one document, in a predictable order, at a page size that prints correctly, without an app and without handing a photograph of your identity documents to someone else's server.

Page order, and how to control it

Browsers do not guarantee the order of a multi-file selection, and the order shown in your file picker is often not the order handed to the page. Sorting by filename is therefore on by default, and it uses natural numeric ordering — page2.heic comes before page10.heic, not after it, which is where plain alphabetical sorting goes wrong.

iPhone filenames like IMG_4471.HEIC sort correctly by this rule because the camera numbers them sequentially. If you need a specific order that the filenames do not express, rename the files first, or turn the option off and select them one at a time in the order you want.

Page size, margins and rotation

A4 and US Letter place each photo centred inside a printable page with a 28-point margin, scaled to fit without cropping. That is what you want when the document will be printed or when a form specifies a paper size. Fit the photo instead makes each page exactly the proportions of its image, converted at 96 dpi, so nothing is ever letterboxed — good for reading on a phone, unhelpful at a print shop.

Turning wide photos sideways rotates the page, not the image, whenever a photo is wider than it is tall. Without it, a landscape photo of a wide form is shrunk to fit the width of a portrait page and ends up small enough to be hard to read.

Quality: what actually happens to the pixels

On Normal and High, each photo is re-encoded as JPEG and embedded with the PDF's /DCTDecode filter — the same approach every scanner app takes, and the reason a twenty-page scan can be two megabytes. Normal is right for documents; the text stays sharp because the photo was sharp, and the file stays small enough to email.

Lossless stores the raw pixels compressed with Flate instead, so nothing is discarded. Images with few distinct colours are written through an indexed palette, which cuts the size by around two thirds without changing a single pixel. Use it when the PDF is an archival copy. Expect it to be several times larger.

The PDF itself is assembled byte by byte by this page's own code. There is no PDF library loaded from a CDN and no server involved, which is also why it works with your connection off.