Overlay One PDF onto Another

Overlay PDF pages without touching a desktop app

To overlay PDF means to lay one document's pages directly on top of another's — picture a company letterhead stamped beneath every page of a report, a "DRAFT" watermark floated over a contract, or a scanned signature placed onto each form in a stack. Unlike merging, which stacks pages one after another, overlaying combines them in place: page one of your overlay lands on page one of your base document, page two on page two, and so on. EzySize's overlay PDF tool does this entirely in your browser, so confidential documents never leave your machine.

Anyone who produces formal documents runs into this constantly. A consultant needs the client's letterhead behind thirty pages of analysis. An office manager has to stamp "PAID" diagonally across last quarter's invoices. A student adds a university crest background to a thesis. In each case the base content already exists and the added layer is identical on every page — doing it by hand in a PDF editor would take an afternoon; an automated overlay does it in seconds.

The tool gives you the two controls that matter for a professional result: opacity and positioning. Opacity decides whether your overlay sits as a faint background tint or a bold foreground stamp, and positioning lets you align the overlay precisely. Because everything processes locally, you can stamp a letterhead onto a sensitive legal document without wondering where the file went afterwards.

How to stamp a PDF background, step by step

1. Upload your base document. Drag the main PDF — the report, invoice batch, or contract — onto the upload area. This is the document whose pages will receive the overlay.
2. Upload your overlay file. Add the second PDF containing the letterhead, watermark, stamp, or background. Design it as a single page if you want the same layer repeated on every page of the base document.
3. Choose the layer order. Decide whether the overlay goes behind the content (a letterhead or background tint) or in front of it (a stamp, a "DRAFT" mark, a signature). Background placement keeps text fully readable; foreground placement guarantees visibility.
4. Set the opacity. For letterheads and background graphics, 20–40% opacity is the sweet spot — visible but never competing with the text. For stamps and watermarks meant to be noticed, 60–80% works; at 100% a large watermark will bury the page content.
5. Adjust the positioning. Center the overlay for symmetrical stamps, or nudge it to a corner for letterhead-style framing. Check the preview on both a text-heavy page and an image-heavy page, since contrast differences change how the overlay reads.
6. Apply and download. Process the file and save the result. Open it and flip through several pages to confirm the overlay sits consistently — a letterhead that drifts by a few millimeters between pages looks sloppy in print.

Practical uses for a PDF overlay tool

Letterhead on every page. Small businesses keep a one-page letterhead PDF and stamp it behind proposals, quotes, and invoices. One overlay pass brands a hundred pages, and the letterhead file can be swapped in seconds when the logo changes.

Draft and confidential stamps. Law firms and consultancies overlay semi-transparent "DRAFT," "CONFIDENTIAL," or "DO NOT DISTRIBUTE" marks across documents under review. A diagonal 45-degree stamp at 50% opacity is the industry-standard look.

Form backgrounds. A scanned paper form becomes a fillable-looking background; the data pages overlay on top. This is how offices digitize legacy paperwork without retyping the form layout.

Certificate and award batches. Design the certificate border once, overlay it onto pages of recipient names. Hundreds of personalized certificates from two files.

Page furniture for reports. Footers, page borders, and approval-signature blocks can live in the overlay layer, keeping the base content clean and letting you restyle the frame without touching the text.

Pro tips for clean, professional overlays

• Design the overlay at the same page size as the base. If your report is A4 and your letterhead PDF is US Letter, the layer will sit off-center or get scaled unexpectedly. Match sizes before uploading — you can standardize pages first with header and footer tools if needed.
• Keep background overlays under 40% opacity. The test is simple: print one page in black and white. If the letterhead interferes with text legibility on a cheap office printer, it will also interfere on screen for anyone reading on a dim monitor.
• Use vector overlays when you can. A letterhead built as vector PDF content stays razor-sharp at any zoom and prints cleanly; a 150-DPI scanned letterhead looks fine on screen but fuzzy on paper. If your overlay is a scanned image, scan at 300 DPI minimum.
• Stamp first, then flatten for distribution. After overlaying, run the result through Flatten PDF so the layers become one — recipients can't accidentally select or move your letterhead, and the file behaves identically in every viewer.
• Watch for double headers. If your base document already has a header with the company name and your overlay adds another, the page looks amateur. Strip or suppress one of them before overlaying.
• Test one page before stamping five hundred. Overlay a single-page excerpt first, check opacity and alignment on screen and in print, then run the full batch. Re-doing a 500-page stamp because the logo was 5mm off is a miserable afternoon.

Overlay one PDF onto another: layering, backgrounds, and alternatives

Stamp PDF background vs. merge PDF as background

People searching for how to merge a PDF as background usually mean overlaying, not merging. True merging appends pages sequentially — your letterhead would appear as page one, then the report follows. Overlaying fuses the two visually on the same pages. If what you want is a letterhead behind existing content, overlay is the right operation; if you want to attach a cover page, use Merge PDF instead.

PDF background stamp opacity and positioning

Positioning matters most for foreground stamps: a "PAID" stamp centered on each invoice page looks official; one drifting into the top-right corner looks accidental. For background stamps, full-bleed centering works because the content flows over it. Diagonal stamps (rotated 45 degrees) read instantly as stamps rather than content, which is exactly what you want for draft and confidential markings — the eye categorizes them as metadata, not text to read.

When a watermark tool is the better choice

If your overlay is just text — "DRAFT," a name, a date — the dedicated Add Watermark to PDF tool is faster, since you type the text instead of designing a PDF for it. Reserve full overlay for graphics: letterheads, logos, scanned signatures, borders, and form backgrounds that can't be expressed as a line of text.

Overlaying is one of those operations that looks like magic the first time you see it — two files go in, one perfectly branded document comes out. Get the opacity right, match your page sizes, and nobody will ever guess the letterhead wasn't there from the start.