Sign a PDF With Your Signature

Electronic signatures and digital signatures are different things

The two terms get used interchangeably and they describe unrelated mechanisms. An electronic signature is a mark applied to a document to show intent to be bound by it. A digital signature is a cryptographic operation: a private key held by a named party produces a value over the document's bytes, and anyone can verify that the value matches both the key and the content.

This tool produces the first. The visible mark records that you signed; the evidence that it was you rests on the surrounding circumstances — the email thread it travelled in, the account it was sent from, the fact that the other party dealt with you. For everyday agreements between parties who already know each other, that is how the overwhelming majority of paperwork has always worked, and a scanned wet-ink signature carries exactly the same evidential weight.

Where a transaction is regulated, the specification usually names the mechanism required, and it will say so explicitly. If the words qualified or advanced appear in the instructions, a certificate issued by a trust service provider is being asked for, and no visible mark satisfies that.

Sizing a signature so it sits properly on the page

PDF measures in points, and there are 72 points to an inch. That single number governs how a signature image lands, because the file you upload is measured in pixels and the page is measured in points.

A handwritten signature on paper is typically somewhere between two and three inches wide. Two inches is 144 points, which is about a fifth of the width of a standard portrait page. Placed at that size it reads as a signature; stretched across half the page it reads as a graphic.

For the image to look sharp at that size when printed, it needs enough pixels behind it. At the 300 dots per inch that print work assumes, a two-inch signature wants roughly 600 pixels of width. A photograph from any modern phone camera has several times that, so resolution is rarely the constraint — framing is. Fill the frame with the signature when you photograph it rather than capturing the whole sheet, because a signature occupying a tenth of a large photo is a small number of usable pixels wrapped in a large number of wasted ones.

A worked example: a three-page rental agreement

Three pages, signature block on the last one, a date line beside it. The file is small — a text-based agreement of this length is well under a megabyte, nowhere near the 100 MB ceiling.

Upload, then use the preview to place the signature. Position it over the ruled line rather than above it; a signature that sits clear of its line looks pasted on, whereas one that crosses the line slightly looks written. Drag it into place at the zoom level you find comfortable — the placement is converted into the document's own coordinates, so what you position is what you get regardless of how far in you were zoomed.

The date beside it is a separate job. This tool places a signature; for the typed date and any initials in the margins, run the signed file through Edit PDF afterwards.

Download, open the result, and look at the whole final page rather than only the signature. Then keep the unsigned original — it is the only clean copy you will have if the counterparty comes back with an amendment.

Signing is the last step, not the first

Order of operations matters more here than with any other tool, because everything else rewrites the file that the signature was applied to.

If several documents are going out as one pack, combine them with Merge PDF first and sign the finished pack. Signing the parts and merging afterwards means the signatures still appear on the page — they were drawn into the content — but you have created a document whose pages were assembled after signing, which is a weaker story than a signature applied to the pack as it stands.

If the file needs to be smaller, compress before signing rather than after. Compression re-encodes images, and a signature is an image the moment it is placed; running it through a downsampling pass afterwards is the usual reason a signature that looked crisp in the preview arrives soft and grey.

The same applies to rotating, cropping and page removal. Get the document into its final shape, read it once more, and sign it last.