Merging PDFs: 7 Best Practices for Clean Documents

Combining a few PDFs into one sounds trivial. In practice, it’s where document polish goes to die — broken bookmarks, mismatched page sizes, fonts that disappear. Follow these seven rules and your merged file will look like it was authored as one.

1. Standardise the page size first

If you’re mixing A4 with Letter, convert everything to one size before merging. Most PDF tools (including ours) preserve the source page dimensions, so a Letter page surrounded by A4s sticks out in print.

2. Decide on a single orientation

If most of your pages are portrait, rotate landscape pages to portrait too. Use Rotate PDF for quick fixes.

3. Order with intent

A good merge follows a clear narrative: cover → table of contents → main → appendix. Drag the files in our Merge PDF tool to enforce this.

4. Add a watermark for drafts

Mark in-progress merges with a clear “DRAFT” watermark. Our Watermark PDF tool does this in two clicks with full control over opacity, color and position.

5. Compress at the end, not in the middle

Compressing every input PDF before merging may seem efficient, but it stacks compression artefacts. Better: merge first, then run the result once through Compress PDF.

6. Preserve searchability with OCR

If any of your inputs are scans, OCR them first using our OCR tool. The merged result will be searchable across every page.

7. Verify the page count

Before sending, open the merged file and confirm the total page count matches your expectation. Most issues with merged PDFs are caught with this 5-second check.

A worked example

Imagine you’re submitting a tax return:

1. Cover letter (1 page Letter)
2. Tax form (3 pages A4)
3. Receipts (12 photos)

Workflow:

1. Convert all photos to PDF: Image to PDF, pick Letter, Fit, High quality.
2. Resize the tax form: open in our Image to PDF tool by extracting pages first, or print to PDF on Letter.
3. Merge in order: cover → form → receipts via Merge PDF.
4. Watermark “Draft v1” using Watermark PDF if you want to circulate before finalising.
5. Compress to under 10 MB with Compress PDF.

A single, polished PDF — done in under five minutes, all in your browser.