Merge PDFs

Combine several PDF files, or pages picked from each of them, into one PDF with the merge command-line tool.

Available in pre-release 3.7

Run sumatrapdf-tool merge -o all.pdf a.pdf b.pdf. At a glance:

Whole files: sumatrapdf-tool merge -o all.pdf a.pdf b.pdf c.pdf
Some pages of each file: sumatrapdf-tool merge -o out.pdf a.pdf 1-3 b.pdf 5
Insert a file in the middle of another: sumatrapdf-tool merge -o out.pdf a.pdf 1-3 b.pdf a.pdf 4-N
Every PDF in a folder: a PowerShell one-liner, see below.

sumatrapdf-tool is installed with SumatraPDF and added to PATH. SumatraPDF.exe merge takes the same arguments. There is no merge command in the SumatraPDF window.

Merge whole files #

sumatrapdf-tool merge -o all.pdf a.pdf b.pdf c.pdf

Files are added in the order you list them.
Put file names with spaces in quotes: "01 intro.pdf".
-o is the file to create. Without -o the result goes to out.pdf.

Pick pages from each file #

Put a page list after a file name to take only those pages. A file without a page list is added whole.

sumatrapdf-tool merge -o out.pdf a.pdf 1-3 b.pdf 5 c.pdf

This takes pages 1, 2 and 3 of a.pdf, page 5 of b.pdf and all of c.pdf.

The page list is comma-separated, with no spaces:

Page list	Pages
`5`	page 5
`1-3,7`	pages 1, 2, 3 and 7
`8-N`	page 8 to the last page (`N` is the last page)
`-1`	the last page; `-2` is the second-to-last
`1--2`	every page except the last
`N-1`	all pages in reverse order

Pages are taken in the order you list them, so the same syntax reorders and repeats pages: see Reorder pages in a PDF. Note: 1-N-1 is not “all but the last page”; it repeats the last page. Use 1--2.

You can list the same file more than once. To insert all of b.pdf after page 3 of a.pdf:

sumatrapdf-tool merge -o out.pdf a.pdf 1-3 b.pdf a.pdf 4-N

Merge every PDF in a folder #

In PowerShell, in the folder with the PDFs:

$files = (Get-ChildItem *.pdf | Sort-Object Name).FullName
sumatrapdf-tool merge -o ..\all.pdf $files

Files are merged in name order. The result is written to the parent folder so running the command again doesn’t merge the previous result too.

Merge images or other documents #

merge reads only PDF files. For anything else it prints Cannot merge document 'photo.png'. and leaves that file out. Convert it to PDF first, then merge:

sumatrapdf-tool convert -O compress -o photo.pdf photo.png
sumatrapdf-tool merge -o out.pdf report.pdf photo.pdf

See Convert images to PDF, Convert EPUB to PDF and Convert comics to PDF.

What the merged PDF keeps #

Bookmarks (table of contents) of each file are copied and point to the new page numbers. Bookmarks to pages you didn’t take are dropped.
Note: with a range written backwards (N-1, 6-4) bookmarks keep their old page numbers. To reorder one file, use clean (Reorder pages in a PDF).
-O sets output options, e.g. -O compress,garbage. See sumatrapdf-tool merge for the list.

Tips #

Check the messages after merging: if a file is missing or isn’t a PDF, merge skips it with Cannot merge document '...' and still writes the output (and still exits with code 0).
Name files 01 ..., 02 ... so a folder merges in the right order.
Write the output to a new file, not over one of the inputs.
Use Compress a PDF if the merged file is large.