Compare PDF drawings without losing track of the revision.

Match the drawing before comparing the detail.

Two files with similar names are not necessarily the same drawing issue. Check the sheet number, title, revision and issue date in each PDF. Use the actual sheet identifier rather than the page's position in the file: adding a cover sheet or deleting a detail can shift every later page number.

For example, page 12 of an earlier set might contain shop drawing MW-204, while MW-204 appears on page 14 in the revised set. Compare MW-204 with MW-204 first. A new page number alone does not mean that the drawing itself changed.

Keep the earlier and revised files clearly named. If the review concerns an issued change, retain its revision reference in the comment so someone reading it later can tell which two issues you compared.

Use side-by-side PDF comparison for a close visual review.

LayrPDF's Split View displays two documents beside each other. You can resize the panes and navigate the PDFs while checking a plan, elevation or detail. This is a manual visual comparison: you identify the differences and decide what needs a markup.

1. Locate the same view

   Open the matching sheet and detail in each revision. Use a stable reference such as a grid intersection, room label or cabinet number to orient yourself.

2. Compare at a useful size

   Zoom until the relevant notes and linework are readable in both panes. Similar screen size helps visual review, but does not establish a measurement scale.

3. Check more than the outline

   Read dimensions, material notes, detail references and schedules as well as the geometry. A changed finish or hardware note may matter even when the drawing looks similar.

4. Record the specific difference

   Place the review comment on the appropriate drawing and identify the earlier and current revisions when needed. Separate an observed change from a question that still needs an answer.

Make the review note useful to the next person.

Consider a sample cabinet elevation where revision B labels an opening 900 mm and revision C labels it 850 mm. A useful note would be: “MW-204, elevation 2: opening changed from 900 mm in revision B to 850 mm in revision C. Confirm appliance clearance against the selected model.” It names the location, describes the change and states the unresolved question.

That is easier to act on than “check size” beside a cloud. The same approach works for a moved partition, a revised panel joint or a changed finish code. Use the values and references on the actual drawing; the dimensions here are only an example.

When measuring either PDF, calibrate and check that revision independently. A different sheet size, export setting or scan can change the relationship between page geometry and real dimensions.

What a drawing comparison does and does not establish.

A manual comparison helps you review the changes you can see. It does not certify that every difference has been found, automatically highlight changed pixels or decide which issue is authorised for fabrication. Use the project team's issued drawing information to establish that status.

Layr brings side-by-side drawing review together with clouds, arrows, notes, measurements and a markup register. After recording a difference, the register helps you find the comment again by page, author or status. Live team markup is available when the review belongs on a shared drawing set.

The Windows app includes a seven-day editing trial with no card or automatic charge. Paid editing then costs US$35 a year or US$5 a month for Solo. Existing work remains readable after the trial.

Common questions