What merging a PDF actually does
Merging takes the pages of several PDF files and places them, one file after another, into a single new PDF. Page 1 of the second file follows the last page of the first file, and so on. Nothing on the pages is re-drawn or re-typed: each page is copied across as it was, so text that was selectable stays selectable, and images keep the quality they already had.
The merged document is a new file called merged.pdf. The files you selected are only read, never changed, so you still have every original on your device afterwards.
When merging is the right tool
- Assembling a single submission. Application portals and HR systems often accept only one upload. Merging lets you combine a cover letter, a CV and supporting certificates into one file in the order the reader expects.
- Combining chapters or sections. Reports, theses and manuals are often exported chapter by chapter. Merging joins them into one document for review or printing.
- Collecting invoices or receipts. Expense claims and bookkeeping are easier with one PDF per month or per project instead of dozens of separate attachments.
- Joining scans made in batches. A scanner or phone app may save each batch — or each page — as its own PDF. Merging puts them back together.
If you only need some pages from each file, it's usually cleaner to trim them first with Extract PDF Pages and then merge the trimmed files.
How to merge PDF files
- Add your files. Drag two or more PDFs onto the upload area, or click it to choose files. You can add more files at any time — they are appended to the bottom of the list.
- Set the order. Files are merged top to bottom. Use the up and down arrows beside each file to move it, and the × button to remove one you added by mistake.
- Merge. Select Merge PDFs (it becomes available once at least two files are listed). The progress bar shows each file being read and combined.
- Download and check. The result shows the total page count and file size. Download
merged.pdfand scroll through it once before sending it anywhere.
Important things to know
Order is set per file, not per page
This tool arranges whole files. If pages inside one file are in the wrong order, fix that file first — typing a custom order such as 1-3, 5, 4, 6-10 into Extract PDF Pages produces a correctly ordered copy you can then merge.
Different page sizes stay different
Pages keep their original dimensions and orientation. Merging an A4 document with a US Letter one gives a PDF that contains both sizes; a landscape spreadsheet printout stays landscape between portrait pages. That is normal and most viewers handle it well, but if the file will be printed, check that your printer's "fit to page" setting is on.
File size is roughly the sum of the parts
A merged file is usually close to the combined size of the inputs. It can come out slightly larger when several files embed the same fonts, because each file's copy is kept. If the result is too big to email, run it through Compress PDF afterwards.
What doesn't carry over
Page content is copied faithfully, but document-level extras are not always preserved: bookmarks (the outline panel), fillable form fields and document properties such as the title may be missing or stop working in the merged copy. If you rely on those, keep the originals and check the merged file in your PDF reader.
Password-protected PDFs
Files that need a password to open can't be merged reliably, because the tool doesn't decrypt them. If you're entitled to the file, open it in the software you normally use, save an unprotected copy, and merge that copy.
Tips for a clean merged document
- Name files so they sort correctly. Prefixes such as
01-cover.pdf,02-report.pdfmake the upload list appear in the right order when you select them all at once. - Put the file the reader needs first at the top. For job applications that's usually the cover letter; for claims it's the summary form.
- Trim before you merge. Deleting blank scan pages or duplicate cover sheets from each source is easier than hunting for them in a long merged file.
- Keep the page count in mind. The result screen shows the total pages — compare it with what you expect to catch a missing or duplicated file.
Common merging problems
- "… doesn't look like a valid PDF"
- One file is damaged, password-protected or isn't really a PDF (for example, a Word file renamed to .pdf). The message names the file. Remove it from the list, re-export or re-download it, and try again.
- The Merge button stays greyed out
- Merging needs at least two PDFs in the list. Files that aren't PDFs are skipped with a warning, so check that both files were accepted.
- Some pages look sideways in the result
- They were already rotated in the source file; merging doesn't change orientation. Fix them afterwards with Rotate PDF using the "Selected pages" option.
- The browser slows down or the tab crashes
- All processing happens in your device's memory. Very large scans (hundreds of megabytes in total) can exceed what a phone or older laptop can hold. Merge in smaller groups, then merge the groups, or compress the biggest files first.
Merge PDF FAQ
No. The files are read and combined by JavaScript running in your browser, and the merged PDF is created on your device. They are not sent to the IQ PDF Manager server as part of merging.
There's no fixed limit on the number of files. The practical limit is your device's memory: dozens of ordinary documents are fine, but several very large scans may be slow on a phone. Each individual file must be under 150 MB.
No. Pages are copied as they are, not converted to images, so text stays sharp and selectable and images keep their existing resolution.
Not in this tool — it orders whole files. Use Extract PDF Pages with a typed page order (for example 2, 1, 3-8) to reorder pages within a file, then merge the result.
Nothing. They are only read. The tool produces a separate merged.pdf download, and your originals stay exactly where they were.
Each source file brings its own images and fonts, and shared fonts are not de-duplicated. If size matters, run the merged file through Compress PDF; image-heavy or scanned documents usually shrink the most.