Merge PDF to a size limit

To merge PDF files into one under a size limit, add the files, put them in order, choose the largest size the result may be, and download the merged PDF. pdfly appends the pages file by file, then checks the size. If the merged PDF is already under your limit, you get it as it is. If it is over, it is compressed until it fits, and you still get one file.

1. Drop 2 to 20 PDFs on the tool, or browse for them. You can add more later.
2. Use the arrows to set the order. The first file in the list becomes the first pages of the merged PDF.
3. Pick a size. 5 MB opens selected because many forms accept it. Choose Custom for any other number.
4. Start the merge and download one PDF.

Most PDF mergers stop once the pages are joined. That is fine until the upload form says the file must be under 2 MB, and three scanned documents together come to 9 MB. Then you go looking for a compressor, guess a setting, and try the upload again.

Here the size is part of the job. A merged PDF weighs about the sum of its files, sometimes a little less once the structure is tidied, so pdfly measures the real merged file and only compresses when that number is over your limit. You see the result size before you download, and a merged file over your limit is never handed out.

When the merged PDF fits, nothing is recompressed: text, images, and vector drawings stay as they were. When it does not fit, the passes run cheapest first. Structural clean-up comes before anything visible, then images are recompressed at the highest quality that still fits.

Rasterizing, which turns each page into a picture of itself, is the last resort. It can make a stubborn file much smaller, but text may no longer be selectable, so it runs only when you tick the box. Compress a PDF without losing quality explains each pass in more detail.

Every page comes across with its text, images, and comments. Bookmarks from the source files are not carried over, and neither are document properties such as the title or the author. Fillable form fields may stop working, so fill forms before you merge them.

A digital signature covers the exact bytes of the file it was made on. Merging writes a new file, so a signature from one of the sources no longer validates. If a form wants a signed PDF, merge first and sign the result. Password-protected PDFs cannot be read and are rejected; remove the password in the app that set it.

Visa, job, school, and benefit portals often ask for one PDF that holds an ID, certificates, and supporting letters, under a fixed size. Scan or export each document, add them in the order the form lists them, and pick the portal's limit. If the result still cannot fit, the portal may accept several files; in that case split the PDF by size and upload the parts in order.

Scans are usually what makes these files heavy. Why is my PDF so large explains why a photographed page can outweigh fifty pages of text, and what to change when you scan the next one.

One attachment is easier to open than five, and many people merge for that reason alone. Gmail and Yahoo Mail accept 25 MB per message and Outlook 20 MB, but attachments grow by about a third when they are sent. Merge to 10 MB and the message clears most office servers. PDF too big to email covers the caps and the overhead.

Preview can combine PDFs: open the first file, show the thumbnails in the sidebar, and drag the other files into it. It does not know your size limit, and its Reduce File Size filter has no setting, so a large merge is often still too big or comes out blurry.

pdfly runs in the browser, so it works the same in Safari or Chrome on macOS, with nothing to install. Compress a PDF on a Mac looks at Preview's filter and its limits more closely.

One merge takes 2 to 20 PDFs, up to 100 MB together and 500 pages in total. The size can be anything from 8 KB to 100 MB. To shrink one file without merging, use the PDF compressor. The uploads and the merged PDF are deleted within 1 hour, and there is no account to create.