How to Sign a PDF on Your Phone Without Printing It
You can sign a PDF on your phone without printing it: open the file in a browser-based signing tool, draw your signature with your finger, place it on the signature line and download the signed copy. With PDF Sign the whole job happens inside your phone's browser, so a lease, a school permission slip or a timesheet never gets uploaded anywhere.
The one part that takes a little care is placement. PDF Sign doesn't let you drag the signature around a page preview; you type in where it goes. Below are the steps, the numbers that get the signature onto the line in one or two tries, and a short explanation of what kind of signature this is, so you know when it's enough and when it isn't.
Before you start
- Have the PDF on your phone. Save the email attachment to your Files app (iPhone) or Downloads (Android) so you can pick it from the browser.
- Remove any password. PDF Sign can't open password-protected PDFs. If the file asks for a password, open it in your PDF reader and save a copy without one first.
- Know which page needs signing. Each run puts one signature on one page.
How to sign the PDF, step by step
- Open PDF Sign in your phone's browser and tap Choose PDF. Pick the document. Its name appears next to the button.
- Draw your signature in the box with your finger or a stylus. The ink is dark blue. If it comes out wobbly, tap Clear signature and try again. Sign large and fill most of the box: a small scribble in one corner ends up tiny on the page.
- Under Position on PDF, enter the Page number where the signature belongs. If you type a number higher than the document has, the signature goes on the last page.
- Set X (distance from the left edge) and Y (distance from the top edge) to move the signature to the line. The next section explains what values to use.
- Set Width and Height. The defaults are 200 by 60.
- Tap Embed Signature, then Download Signed PDF.
- Open the downloaded file and check where the signature landed before you send it.
The signed file keeps your original name with -signed added, so lease.pdf becomes lease-signed.pdf. That makes it easy to tell the two apart in your downloads.
Getting the signature onto the line
X and Y are measured in PDF points. A point is a small fixed unit that PDF files use for measuring pages: one point is 1/72 of an inch. You don't need to measure anything yourself; you only need to know roughly how big the page is in points.
| Page size | Width (points) | Height (points) | Typical bottom signature line (Y) |
|---|
| A4 | about 595 | about 842 | roughly 700 to 780 |
| US Letter | 612 | 792 | a bit smaller than on A4, since the page is shorter |
So on an A4 rental form with the signature line near the bottom, a first try of Page 2, X 300, Y 740 puts the signature around the middle of the page, near the bottom. If the line is on the left, start with an X around 70 to 100.
The first attempt is a guess. Here's how to correct it quickly:
- Open the signed copy and note how far off the signature is. Too high? Increase Y. Too far right? Lower X.
- Adjust X or Y by that amount. For a rough sense of scale, 72 points is one inch, or about 2.5 cm.
- Tap Choose PDF and pick your original file again, not the signed copy, or you'll end up with two signatures.
- Your drawing stays in the box, so you only need to tap Embed Signature once more and download.
Keep the signature from looking squashed
Your drawing is stretched to fit the Width and Height you enter. The drawing box is about four times wider than it is tall, so keep that shape. 240 by 60 or 200 by 50 look natural; 200 by 100 makes the signature look tall and thin. The background of the signature is transparent, so the form's printed line still shows through underneath it.
Signing more than one page or adding the date
PDF Sign places one signature on one page per run. If a contract needs a signature on page 3 and initials on page 5, run it once for page 3, then choose the signed file and run it again for page 5. Choosing the signed file is right here, because you want to keep the first signature.
The tool only draws signatures. It doesn't type a name in a font, accept a photo of your signature, or fill in form fields. For a printed name, the date or a reference number beside your signature, use Add Text to PDF on the signed copy.
If you've been asked to sign several separate files and send them back as one, sign each with PDF Sign and then combine them with PDF Merge.
Is a drawn signature legally valid?
What PDF Sign produces is an image of your handwritten signature on the page. That's generally treated as a simple electronic signature, and it's accepted for many everyday documents: rental applications, school forms, timesheets, delivery notes.
The law in many places is broad about what counts. In the US, the federal ESIGN Act defines an electronic signature as an electronic sound, symbol or process attached to or associated with a record and adopted by a person with the intent to sign it. In the EU, the eIDAS Regulation says an electronic signature can't be refused legal effect or as evidence simply because it's electronic. Rules for specific documents still differ by country and by organisation.
A drawn signature is different from a certificate-based digital signature. That kind uses a cryptographic certificate, a digital ID issued to you, to prove who signed and to show whether the file was changed afterwards. Under eIDAS, the highest level, a qualified electronic signature, has the same legal effect as a handwritten one across EU member states. Some banks, courts, government offices and businesses require a certificate-based signature, and PDF Sign doesn't create one.
If you're not sure which the sender needs, ask the person or organisation that sent you the document what they accept. It's a quicker question than redoing a mortgage form.
Why sign in the browser instead of an upload site
Leases, employment contracts and consent forms often carry your address, ID numbers and bank details. With PDF Sign, the PDF is opened, signed and saved inside your browser using the pdf-lib library. Neither the document nor your signature is uploaded to our server. On a phone that's especially useful, because you're often signing on mobile data or public Wi-Fi and may not want the file going anywhere extra.
When your phone's built-in tool is the better choice
iPhones and many Android phones include their own fill-and-sign or markup tools for PDFs, and Apple's iPhone User Guide covers filling out forms and signing documents. Those tools usually let you drag the signature into place on a preview, which is quicker than typing numbers if you sign a lot of documents. PDF Sign is the better fit when you'd rather not set anything up, when you're on a shared or work phone, or when you want the same steps on any device with a browser.
If the document needs a signature on one page and you have two minutes, PDF Sign will do it. If it needs a certificate-based signature, ask the sender which service they use before you sign anything.
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