The usual reason for this is that something will only accept a PDF. Photographed receipts for an expense claim, pictures of documents for an application, a set of pages captured with a phone rather than a scanner — all of it needs to arrive as one document, and photographs are what you have.
The JPEG data is embedded, not re-encoded
This is the detail that separates a good conversion from a lazy one. PDF can carry JPEG data natively, so your photo's original compressed bytes go straight into the document untouched. There is no decode-and-re-encode step, which means no second round of compression and no loss of quality at all.
The practical test is file size: a 3 MB folder of photos produces a PDF of roughly 3 MB. If a converter gives you something much larger, it decoded your images and re-saved them, probably as PNG. If it gives you something much smaller, it re-compressed them and threw away quality you may have needed — which matters when the photograph is of a document someone has to read.
Page size follows the photo
By default each page is made exactly the size of its image, so nothing is scaled, letterboxed or cropped. Portrait and landscape photos each get a page of the right shape, and the PDF is a faithful container rather than an attempt to lay anything out.
Choose a paper size instead when the document will be printed. Each image is then centred on an A4 or Letter page with a margin, scaled to fit while keeping its proportions. Mixed orientations still work — a landscape photo simply sits smaller on a portrait page.
Order matters, so it is yours to set
- File pickers return files alphabetically, which puts IMG_10 before IMG_2.
- The list is the page order; the arrows change it.
- Adding more photos later appends them rather than reshuffling what you arranged.
- For photographed documents, check the order before combining — a receipt claim in the wrong sequence gets sent back.
A note on size
Phone photos are large, and twenty of them make a PDF too big for many upload forms. Compressing the images first, then converting, produces a far smaller document than converting first — and it lets you choose the quality rather than having it chosen for you. Everything runs in this tab, so nothing is uploaded either way.
Check the result before sending it
Open the finished PDF and look at every page, particularly if it was assembled from photographs of a document. The two things that go wrong are pages in the wrong order and a page that is unreadable because the photograph was blurred or badly lit. Both are much easier to fix now than after a submission is rejected.