Why didn't merging make my PDF smaller, and what do I do when it is now too big to email?

Where the size comes from

In most shop and office files, images carry the weight: a scanned ID, a catalog full of product shots, a bill photographed on a phone. Text on its own is tiny. Merge three files with pictures in them and you have simply gathered three sets of pictures into one file; nothing in a merge makes them lighter.

That is why Merge PDFs shows each file's size in the list, and the size of the result in the message after merging. Add up the sizes at a glance before you press the button and you will know roughly what to expect.

Over the email limit: three ways out

1. Send it in two parts: open the merged file in Split PDF, cut it at a sensible point such as the end of one document, and send each part in its own message.
2. Shrink the photos at the source: if some pages are phone pictures, compress them first with the Image compressor, turn them into a PDF, then merge.
3. Do not merge everything: sometimes it is enough to combine the light documents and attach the heavy one separately.

Do not trust a limit you heard about

Attachment limits vary between mail services, they change, and the person receiving may have a smaller limit than yours. Check the current limit in your own service and leave some headroom, because email encodes attachments as text on the way, which makes them roughly a third larger than on your disk. If a file is very close to the limit, treat it as over.

• Merging again will not make the file smaller, so there is no point repeating it.
• Splitting does not change page quality; each part stays as sharp as before.
• If the recipient insists on one file, ask about another way to upload rather than crushing the images.