Five things worth checking before you merge PDFs
4 min read
The merge itself is instant. What costs time is discovering a problem afterwards and doing the whole thing again.
1. Tidy up the filenames first
When you select several files at once, most browsers hand them over in filename order. That order is textual, so “doc(10).pdf” often lands before “doc(2).pdf”.
Padding numbers as 01, 02, 03 makes the sort behave the way you expect. If the files are already in the list, you can drag the cards — or use each card's move buttons — to fix the order before you run anything.
2. Check for mixed orientation
If the body is portrait but an appendix table is landscape, whoever reads the merged file has to rotate their screen partway through. Printing makes it worse.
Check each document's orientation first and, if needed, use the rotate tool to make them consistent before merging.
3. Watch out for different page sizes
Merging an A4 document with a Letter one gives you a file whose pages change size partway through. On screen it's easy to miss; printed, the margins visibly shift.
The PDF Info tool lists the size of every page and warns you when a document mixes them.
4. Filter out password-protected files
A PDF with an open password can't be read, so it can't be merged. Discovering that halfway through a batch is annoying to diagnose.
If the batch includes files from an institution or old archives, check their status first.
5. Predict the final size
A merged file is usually about as large as the sum of its parts. If your mail limit is 25MB and the sources are 12MB and 15MB, the merged file won't attach.
You can try compressing, but depending on the document it may barely shrink. Sending two files is sometimes simply faster.