Put PDFs together

Start from what you have

If every part is already a PDF, use Merge PDFs. Drop the files in, set the order, and download one file. Page order follows the order you set, and nothing is re-rendered.

If the parts are photos or screenshots, they need to become pages first. Images to PDF does that in one step, so there is no reason to build a document per image and merge afterwards.

If you scanned a stack one page at a time and ended up with a folder of single-page files, treat them as PDFs and merge, but check the order before you download. Scanners name files in ways that do not always sort the way you expect.

Order is the part people get wrong

Merging is easy. Getting page 7 to sit after page 6 is the part that fails. Set the order in the tool rather than trusting the file names, and open the result before you send it. One reversed pair is invisible until someone else finds it.

File names lie in creative ways. Scanners stamp times that sort wrong across midnight, phones number bursts out of sequence, and downloads arrive named after the sender's internal system. The order you set by hand is the only order that counts.

If a merged file needs pages moved after the fact, Organize pages can reorder and delete without building the document again.

What merging does to the file

Merging copies page objects from each source into one new document. Text stays selectable, links inside a page keep working, and page size stays whatever each source page was. Mixed page sizes stay mixed, which surprises people who expect a merge to normalise everything to A4.

Nothing is re-rendered, so nothing is lost in translation either. A page that looked sharp in its source looks identical in the result, and a page that was broken stays broken in exactly the same way. Merging never repairs and never degrades; it only concatenates.

Why the result is bigger than the parts

People expect one file to be smaller than several. It is usually slightly bigger instead. Each source brings its own embedded fonts, and two files that use the same typeface embed it twice rather than sharing. Images arrive untouched at full resolution, because a merge that recompressed them would be editing, not joining.

If the combined file is too big to send, that is a separate job with a separate tool. Compress PDF takes the merged file down to a size you name, and checks that the text survived the trip. Merge first for order, compress second for size, and check once at the end.

Bookmarks, forms and other passengers

Page content always survives a merge. Document-level extras are less certain, and the honest answer depends on the files. Bookmarks that pointed at pages of one source may point nowhere useful in the combined file. Form fields with the same name in two sources can collide and share a value they should not share.

For ordinary reading and printing none of this matters. If the merged file is a form people fill in, or a manual people navigate by bookmarks, open the result and test exactly those features before you send it. The page check at download time covers pages and text, not interactive behaviour.

Scanned stacks need one more pass

Phone and flatbed scans arrive as loose files with unhelpful names, and merging them in filename order is how page 7 lands after page 11. Sort by content, not by name: open each scan, read the first line, and only then set the order.

Merge first, compress second. A folder of phone photos merges into a huge file, because every image arrives at full resolution. That is correct behaviour, not a failure. Once the order is right, take the combined file down to a sending size with Compress PDF and check that every page survived.

Duplex scans add blank backs throughout. Deleting them after the merge is faster than cleaning each file first, because you see all the blanks in one thumbnail view instead of opening twelve files.

When not to merge at all

Not every pile of files wants to become one document. If the parts go to different people, if they update on different schedules, or if one of them is a form that must stay fillable on its own, keep them separate and send them together instead.

Merge for reading order: a report with its appendix, an application with its attachments, a manual with its cover. Everything else is usually better as several files with clear names than as one file nobody can navigate.

Merge, compress, check: the order

Three operations, one correct sequence. Merge first, because order decisions need the full picture in one thumbnail view. Compress second, because the combined size is the only size that matters for sending. Check last, because the check must cover the file that travels, not an intermediate.

Never check an intermediate. Verifying the parts before merging proves nothing about the whole, and compressing after the check writes a new file the check never saw. The thirty-second page-through belongs at the very end, on the download that leaves the tab.