How to Add a Seal to a PDF or Word Document

It is ten to five, the quotation has to go out today, and the client has asked for it "signed and stamped." You have a seal image. You drop it into the Word file, and the whole signature block jumps to the next page. You drag it back, the paragraph above it rewraps, and now the total is split across two lines. Ten minutes later the seal sits in a white box half covering the date.

Every one of those problems has a simple cause, and none of them is the seal. This guide walks through placing a seal in the tools people actually use, then the checks that keep it in place once the file leaves your computer.

Before you start: one clean file at the right size

Two things decide whether placement is painless:

A transparent background. If the seal file has a white or colored background, it will cover whatever is underneath. Export a PNG with the transparent background setting on, and check it on a dark background before using it. The transparent PNG seal guide explains how.
Enough pixels for the size you need. A company seal on an A4 page is commonly around 40 mm across. At 300 DPI that is roughly 470 pixels. A smaller file will look soft when printed. The seal size and resolution guide has the conversion.

If you made the seal in the seal generator, you can skip a step: it can export a Word file or a PDF containing the seal at its true physical size, and it can hand the seal straight to the browser-based PDF and Word stamp tools.

Microsoft Word (Windows and Mac)

Word's default is to treat an image like a very large letter sitting in the line of text. That is why the document reflows when you insert it. The fix is to take the image out of the text flow.

Insert the image. Insert › Pictures › This Device, and choose the PNG.
Change the wrapping. Click the image, then the Layout Options icon beside it (or Picture Format › Wrap Text). Choose In Front of Text. The seal now floats above the page and the text stops moving.
Position it. Drag it to the signature block, overlapping the signature line or company name slightly if that is the local habit. Hold Shift while dragging a corner to resize without distortion.
Set an exact size. Right-click › Size and Position (Format Picture on Mac), lock the aspect ratio, and type the width in millimeters or centimeters, such as 4 cm for a 40 mm seal.
Pin it to the page. In Layout Options, choose Fix position on page. Otherwise the seal is anchored to a paragraph and travels with it when someone edits text above.

One more setting is worth changing once: File › Options › Advanced › Image Size and Quality › Do not compress images in file. Word compresses images by default when saving, which can soften a crisp seal.

If you need the seal on every page, put it in the header or footer instead of the body (double-click the header area, insert, set it to In Front of Text). If you would rather not touch the Word file at all, the browser-based Word stamp tool lets you place a seal on any page of a .docx, or repeat it on every page through the header, and download the stamped file.

Google Docs and other editors

Google Docs: Insert › Image › Upload from computer. Click the image and choose In front of text from the toolbar that appears below it. Use Image options › Size & Rotation to set the size. Google Docs measures in inches or percentages rather than millimeters, so convert first: 40 mm is about 1.57 inches.

WPS Office: the workflow mirrors Word. Insert › Picture, then set the wrapping (环绕) to In Front of Text (浮于文字上方).

LibreOffice Writer: Insert › Image, then right-click › Wrap › Wrap Through, and set the anchor to To Page if the seal should not move with the text.

In every editor, the pattern is the same: insert, take it out of the text flow, size it exactly, and anchor it to the page.

Adding a seal to a PDF

PDFs are not designed to be edited, so you are adding the seal as an image or annotation on top of an existing page. There are three common routes.

In the browser, without installing anything. The PDF stamp tool opens the PDF locally, lets you drag the seal into place, resize it, set its opacity, and choose whether to stamp one page, every page, or a riding-seam seal across the page edges. It then flattens the seal into the exported PDF. Nothing is uploaded. How to stamp a PDF without Acrobat walks through it in detail.

Adobe Acrobat Pro. Use Edit PDF › Add Image to place the PNG, or create a custom stamp under the Stamps tool if you will reuse the same seal often. Custom stamps are convenient, but they remain annotations that a recipient with Acrobat can select and delete unless you flatten the file.

Preview on Mac. Open the seal PNG in Preview, select all and copy, then open the PDF and paste. The seal appears as an object you can drag and resize. Export or save as a new PDF afterward.

Whichever route you take, zoom to 100% and check that the seal is not covering the amount, date, signature, or a printed name.

Every page, or across the page edge

Some counterparties expect a seal on every page, and in parts of East Asia multi-page contracts carry a riding-seam seal split across the page edges, so that pages cannot be swapped unnoticed.

Every page in Word: put the seal in the header or footer, or use the Word stamp tool's every-page option.
Every page in a PDF: the PDF stamp tool's "every page" scope places the seal in the same position on each page.
Riding-seam seal: this needs the seal split into slices that line up when the pages are fanned. Doing it by hand is tedious and error-prone; the PDF stamp tool splits the seal by page count automatically.

The seal placement guide covers where seals usually go on contracts, invoices, and certificates, and seals on contracts explains the contract-specific conventions.

Lock it down before you send

A seal floating in an editable Word file can be moved, resized, or deleted by anyone who opens it, and it can shift when the recipient's version of Word lays out the page differently.

Export to PDF. In Word: File › Save As › PDF (or Export › Create PDF). Choose the standard, not the minimum, size option so images are not downsampled.
Open the PDF in a second viewer. A browser's built-in viewer is fine. Check that the seal is where you put it and that nothing behind it is hidden.
Check the file size. A single-page PDF that has grown to 15 MB usually contains an oversized image. Re-export the seal at the size you actually need.

If the recipient specifically asked for an editable Word file, ask whether they want the seal on it at all. Many people only want the seal on the final signed PDF.

Troubleshooting the usual problems

White box around the seal: the file is a JPG or a PNG with a background. Re-export as a transparent PNG.
The seal jumps when text changes: it is anchored to a paragraph. Use In Front of Text and Fix position on page.
Blurry when printed: too few pixels, or Word compressed it. Re-export larger and turn off image compression.
Looks pasted rather than stamped: a tiny rotation of 2 to 5 degrees, a slight overlap with the signature line, and normal ink opacity look more natural than a perfectly upright, oversized seal.
Prints too pale: some printers lighten pure red. Check a test print and adjust the color rather than enlarging the seal.

What placing a seal does not do

Placing a seal image makes a document look stamped. It does not prove who placed it, and it does not stop someone from changing the document afterward. For routine quotations and letters that is often all anyone expects. For documents that must carry legal weight, use a proper signing process. Are image seals legally valid? and electronic seal vs. electronic signature explain where the line is.

When you are ready, design the seal in the seal generator and export it at the size your document needs.