Adobe Acrobat Pro compares two PDFs with its Compare Files tool: open Acrobat Pro, choose the tool, pick the old file and the new file, and Acrobat builds a results document with a summary of the differences, the two versions side by side and the changes highlighted. It works well for text documents. For drawings, Acrobat can compare the page as an image (it detects the type or you choose it), and the result is often large highlighted areas rather than the exact lines that moved, which is why an overlay is often easier to read on drawing sheets. Compare Files is in Acrobat Pro, not in Acrobat Standard or the free Reader. In the US it costs US$19.99 a month on an annual plan, or US$29.99 a month without a commitment (Adobe pricing page, October 2026).
How do you compare two PDFs in Acrobat Pro?
- Open Acrobat Pro and choose Compare Files from the tools (search for "Compare" if it is not pinned).
- Select the old file on the left and the new file on the right. You can limit each side to a page range, which matters for large sets.
- Open the settings and choose the document type. Acrobat can detect it, or you can choose one; the "Scanned documents, drawings or illustrations" type compares the pages as images.
- Run the comparison. Acrobat opens a results document that starts with a summary page.
- Step through the results. You can view both files side by side, or one file at a time with all changes highlighted, and filter the changes by type.
What does the result show?
For text, Acrobat marks changed content in both versions, colour-coded by type of change. It can also compare annotations, formatting and backgrounds, but those are switched off by default, so a changed comment or a changed background will not show unless you turn them on. For drawings, the comparison is made on page images, so the changes come back as highlighted areas on the sheet rather than a list of lines.
Why does Acrobat mark huge rectangles on my drawing?
Because the drawing is compared as an image, small changes spread across a sheet are grouped into areas. Users report highlighted areas that cover large parts of the sheet. Two other causes make it worse:
- The sheets do not line up. A different page size, scale or export offset makes every line look changed. See why a drawing comparison shows everything as changed.
- One file is a scan. Noise and a slight skew read as changes everywhere.
If you need to see which line moved, an overlay that draws both revisions in two colours is easier to read on drawing sheets.
"Acrobat could not compare the documents completely": what helps?
Users report this message, and on Mac "Acrobat could not create the report document", mostly with large or complex files. Things that are reported to help:
- Compare a smaller page range at a time instead of the whole set.
- Make sure both files are local, not open from a sync folder that is still downloading.
- Print both files to PDF again and compare the new copies (a workaround users report when a file has an unusual structure).
- Update Acrobat, then try again.
Users in Acrobat's community also report that large documents (100 pages or more) can make Acrobat unresponsive during a compare, so split long sets.
When is Acrobat the right tool, and when is an overlay better?
| You are comparing | Use |
|---|---|
| Specifications, contracts, reports | Acrobat Compare Files: a list of word changes |
| Plans, sections, details exported from CAD or BIM | An overlay: both revisions on top of each other in two colours |
| Schedules and title blocks on drawing sheets | Either: text stays in place, so an overlay shows a changed label exactly where it sits |
| Scans | A tool with manual alignment, and expect noise; ask for the native PDF where you can |
For a neutral overview of the tools that offer an overlay (and what each one costs), see drawing revision compare tools, compared.
Comparing drawing revisions as an overlay in Ncored
In Ncored, the PDF editor we built in our architecture studio, you open the newer revision and drag the older PDF onto the sheet. The two appear as one overlay: blue for what the newer revision added, red for what it removed, grey for what stayed the same, with a slider that fades the grey. On a whole set, pages are paired by how they look, so an inserted sheet does not shift the rest. Nothing is written into either file, and it runs on your own computer on Windows and Mac. It does not produce a report document or a list of text changes, so for contracts and specifications Acrobat's Compare Files is still the better fit.
Frequently asked questions
Can Acrobat Standard compare PDFs?
No. Compare Files is part of Acrobat Pro. Acrobat Standard and the free Acrobat Reader do not include it.
Can Acrobat compare scanned drawings?
Yes. Scans, drawings and illustrations are compared as images. Expect more noise than with native PDFs, because a scan is never perfectly straight or the same size.
Does Acrobat compare markups and comments?
It can, but annotation differences are switched off by default. Turn them on in the comparison settings if changed comments matter.
Can Acrobat compare a whole drawing set?
Yes, with page ranges for each file, and in its scanned and drawings mode it can detect pages in a different order. Very large sets can make Acrobat slow or unresponsive, so compare long sets in parts.
Related: how to review a revised drawing set, how to compare two PDF files for differences, how to cancel an Adobe Acrobat subscription.
Adobe and Acrobat are trademarks of Adobe Inc. Ncored is an independent product by Noir architects and is not affiliated with, sponsored by, or endorsed by Adobe. Individual experiences may vary.