MRS BlogHow to sign a PDF on iPhone and send it back in minutes
How do I sign a PDF on my iPhone?
Open the PDF in Files, tap Markup, tap the add button and choose Add Signature, sign with your finger, tap Done and drag the signature into place. A scanner and PDF app such as MRS does the same for paper forms: scan or import, draw your signature once, place it, add the date and share the signed PDF.
Key takeaways
- Markup in Files, Notes and Photos can add a saved signature to a PDF for free.
- A PDF app like MRS adds a scanner, blue or black ink, rotation and a library that finds signed documents by the words inside them.
- A signature you draw on the screen is a visual electronic signature, which most everyday forms accept.
- Wills, court papers and some regulated contracts need other formats, so ask the sender when in doubt.
- Add the date and your printed name with a text tool, then check every page before you send.
A lease renewal lands in your inbox in the evening with a line that says "please sign and return by tomorrow", and you have no printer. This guide shows how to sign a PDF on iPhone, how to add a signature to a PDF with the tools already on your phone or with a scanner app, and what that signature counts for.
Why signing a PDF on iPhone beats print, sign, scan
Signing a PDF on iPhone removes three steps: printing, signing with a pen and scanning the page back. The old way also costs quality, because every print-and-scan cycle adds grey edges, skew and a bigger file. A signature you place on the PDF itself keeps the original pages sharp and the file small enough for email.
Most forms that reach you by email are ordinary paperwork: a school permission slip, a rental application, a freelance contract, a consent form from a clinic. The sender wants to see your signature, your name and a date on the right line. Your iPhone can do all three in a few minutes.
Two paths: sign it yourself, or sign through a request
Signing a PDF happens in one of two ways. In the first, you receive a file, place your signature on it and send it back; this post covers that path. In the second, the sender uses a signature-request service that emails you a link, guides you through the fields and keeps a record of who signed and when.
If the email contains a "Review and sign" button, the sender chose the second path, and you sign inside their service. If it contains a plain PDF attachment, the rest of this guide applies.
How to sign a PDF on iPhone with Markup
Markup, the drawing and annotation tool built into iOS, can sign a PDF without any extra app. According to Apple's iPhone User Guide, you open the document, and if iOS prompts you, you open it in the Files app and tap Save. Then you tap the Markup button, tap the add button, choose Add Signature, sign with your finger and tap Done.
The signature appears on the page, and you drag it onto the line. Blue dots on its frame let you resize it. iOS saves the signature, so next time you pick it from a list, and you can keep several, such as a full signature and your initials.
Where to find Markup in Mail and Files
Markup sits in the toolbar of the document preview. In Mail, tap the PDF attachment to open the preview; in Files, tap the file. Apple lists Notes and Photos as other supported apps, and in Photos the same Add Signature option works on a picture of a document.
Markup covers a single PDF well. For a form you have only on paper, scan it first, for example with the document scanner in Notes, and then sign the scan.
How to sign a PDF with MRS, step by step
MRS is an iPhone scanner and PDF editor with a Sign document tool built for this job. The steps below take a form from your inbox, or from paper, to a signed PDF you can send.
- Open Sign document. In MRS, open Tools and tap Sign document. Scan a paper form with the document camera, which finds the page edges and straightens them, or import the PDF you saved from Mail to the Files app.
- Let the editor open. After the scan or import, MRS opens the PDF editor ready to sign, so you skip the search for the right tool.
- Draw your signature. Sign on the pad with your finger, and pick black or blue ink. Blue ink shows the recipient at a glance which mark is the signature.
- Place it on the line. Move, resize and rotate the signature until it sits on the signature line at a natural size. Rotation helps on a scan that came out slightly tilted.
- Add the date and your name. Tap the text tool, tap next to the line and type the date and your printed name. You can pick from 7 fonts, sizes 12 to 48 and 9 colors.
- Check and share. Scroll through every page, then open the iOS share sheet and send the PDF by Mail, Messages or AirDrop, or save it to Files.
Get MRS: scan, sign and search your papers
Scanner with automatic edges, text recognition (OCR) for searchable PDFs, a PDF editor and saved signatures, on your iPhone. Your pages stay on your device.
MRS saves your 5 newest signatures on the iPhone, so the next form takes two taps: open the signature list and tap the one you want. Scanning, text recognition and signing are free; sending the signed PDF from MRS is part of MRS Premium, and prices are shown in the app.
The part people get wrong: signature size
A signature that fills half the page looks careless, and one the size of a comma looks like a smudge. Aim for the height of about two lines of the form's text and a width that fits the signature line without crossing the printed label. Zoom in before you let go, then zoom out to see the whole page the way the recipient will.
Markup vs MRS vs a signature-request service
Markup, MRS and a signature-request service such as DocuSign solve different parts of the same job. The table compares what each one does for someone signing a PDF on an iPhone.
| Markup (iOS) | MRS | Signature-request service | |
|---|---|---|---|
| Where it lives | Built into iOS: Files, Notes, Photos, Mail previews | iPhone app, iOS 16 or later | Web and mobile apps; the sender needs an account |
| Paper forms | Scan in Notes, then sign with Markup | Scan document with edge detection, then Sign document | Sender uploads the file |
| How you sign | Finger | Finger, black or blue ink | Draw, type or pick a style inside the service |
| Saved signatures | Several, with labels such as initials | 5 newest, reused in two taps | Stored in your account |
| After placing | Move and resize | Move, resize and rotate; add text, drawings and images | Fields placed by the sender |
| Find it later | Files search | Library with folders; search finds words inside scanned pages | Sender's account keeps the record |
| Sending | Share sheet | Share sheet with MRS Premium | The service emails signers and tracks progress |
Which one to pick
Markup is enough for a single PDF that arrived by email and needs one signature. MRS fits when the form starts on paper, when you sign often and want your signatures and signed copies in one searchable library, or when you want blue ink that stands out from the printed text. A signature-request service fits the sender's side: DocuSign describes its product as a way to send, sign and track documents, which matters when several people must sign the same contract.
Is a signature drawn on your iPhone legally valid?
A signature you draw on the screen is an electronic signature: a mark you attach to a document with the intent to sign. It is a picture of your handwriting placed on the page, which is different from a certificate-based digital signature that uses cryptography to prove identity and detect changes. The Wikipedia article on electronic signatures explains that the two terms describe a legal idea and a technical method.
In the United States, the ESIGN Act states that a signature or contract may not be denied legal effect solely because it is in electronic form. In the European Union, the eIDAS regulation says no electronic signature can be refused in court only because it is not an advanced or qualified one, and it gives qualified signatures the same effect as handwritten ones, as the eIDAS overview summarizes.
When to ask the recipient first
The ESIGN Act lists exceptions: wills and testamentary trusts, adoption and divorce matters, court orders and filings, and notices such as eviction or foreclosure. A bank, a notary or an employer can also require a specific process. When a contract is regulated or high value, ask the sender which signature they accept before you sign; this post is general information, not legal advice.
Common mistakes when you sign a PDF on iPhone
Most rejected forms fail on small details, not on the signature itself. Check these before you press send.
- Signing the wrong copy: a reply to an old email can carry last year's version of the lease. Open the newest attachment and check the dates on the first page.
- Missing pages: a contract may need a signature on page 3 and initials on page 7. Scroll every page and look for lines, boxes and the word "initial".
- No date or printed name: many forms ask for "signature, printed name, date" on one line. Add all three with the text tool.
- A blurry scan: a form you scanned in dim light is hard to read after signing. Rescan it by a window, flat on a dark table, as the guide to scanning like a pro with your iPhone explains.
- Sending a photo instead of a PDF: a screenshot of the signed page loses the other pages and the text quality. Share the PDF file itself.
Edge case: a form with fillable fields
Some PDFs have boxes you can type into, built by the sender's software. In Files, Markup lets you tap a blank field and type, and iOS AutoFill can fill several related fields at once from your contact card. MRS fills these forms by placing text on top of the page, which prints and reads the same; the PDF editing basics on mobile guide covers text boxes and alignment in detail.
Your PDF signing checklist and next steps
Before you hit send, run through five checks. They take a minute and save a second round of emails.
- Right document: the newest version, with the correct names and dates on page one.
- Every signature line: signed, with initials wherever the form asks for them.
- Date and printed name: typed next to each signature in a clear font.
- Readable pages: straight, sharp and in the right order.
- A copy for you: the signed PDF saved where you can find it again next year.
If you sign forms every month, keep them together. MRS stores signed PDFs in a library with folders, and its search finds a document by the words inside a scanned page, so "lease" or a landlord's name brings the file back.
For a full system for your papers, read going paperless in one weekend, start with how to scan documents on iPhone, or download MRS. Questions about the app go to MRS support.
Frequently asked questions
Can I sign a PDF on iPhone for free?
Yes. Markup, built into iOS, adds a signature to PDFs in Files and to images in Photos at no cost. MRS lets you scan, sign and save for free; sharing the signed file from MRS needs MRS Premium, and prices are shown in the app.
Is a signature drawn on an iPhone legally binding?
In the U.S. the ESIGN Act says a signature may not be denied legal effect only because it is electronic, and EU rules say the same. Some documents, such as wills and court papers, are excluded, and a recipient can ask for a specific format. This is general information, not legal advice.
How do I sign a paper form that I only have on paper?
Scan it first. MRS has a Sign document tool that opens the document scanner, turns the pages into one PDF and then opens the editor ready for your signature.
Where are my saved signatures stored?
Markup keeps your signatures in iOS so you can pick one next time. MRS stores your 5 newest signatures on the iPhone itself, protected by iOS file protection, and does not upload them. Turning the phone sideways gives you a wider pad when you draw a new one.
What is the difference between an electronic and a digital signature?
An electronic signature is any mark or process you attach to a document with the intent to sign, such as a drawn signature. A digital signature is a cryptographic method that proves who signed and that the file did not change. Drawing on the screen creates the first kind.
