How to edit a PDF on iPhone: add text, sign and send it back

A PDF arrives from your landlord or your kid's school with the note "fill this in and send it back today", and all you have is an iPhone. How to edit a PDF on iPhone comes down to three small jobs (type, sign and draw), and each takes a minute. Below: how to add text to PDF on iPhone pages so it looks printed, where to sign, and how to edit PDF on iPhone for free with tools you already have.

Why editing a PDF on iPhone works differently

Editing a PDF on iPhone means adding things on top of a finished page, because a PDF is a fixed layout. The format describes a complete fixed-layout document, with its text, fonts and images locked in place so it looks the same on every screen. That is why a PDF opens the same way on your phone and on the recipient's laptop, and also why you cannot retype a paragraph the way you do in a Word file.

Phone editors respect that. They let you place new text, drawings, images and signatures on the page, and they leave the original words alone. For the paperwork most people get (forms, letters, leases, permission slips), that is all you need.

The three jobs: type, sign, draw

Almost every edit you make on a phone falls into one of three jobs:

• Type: put text on the page. Names, addresses, dates, amounts, answers to form questions.
• Sign: place your handwritten signature where the document asks for one.
• Draw: make a mark by hand. A tick in a box, a circle around an option, an arrow to a note.

The skill is picking the right job for each spot on the page. A typed signature looks unsigned, and a hand-drawn address looks rushed. Match the job to the field and the page looks like it came off a desk.

How to edit a PDF on iPhone, step by step

Editing a PDF on iPhone takes seven steps in any editor; the example here is MRS, a PDF editor for iPhone that needs iOS 16 or later.

1. Get the PDF into the app. Save the attachment to the Files app, then import it into MRS with "Import file". If you only have the paper, scan it first; our guide on scanning with your iPhone covers light, angle and edges. Imported PDFs keep their pages unchanged.
2. Zoom in on the first field. Pinch to zoom until the line you want to fill is large on the screen. Placing text at full zoom-out is where most crooked results come from.
3. Type the text. Choose the text tool, tap the spot and type. MRS gives you 7 fonts (Helvetica, Times New Roman, Georgia, Avenir Next and others), sizes from 12 to 48 and 9 colors. Black Helvetica at 12 blends in with most printed forms.
4. Add your signature. Draw it once with your finger, in black or blue ink. MRS keeps your newest 5 signatures, so the next document takes two taps. Move, resize and rotate the signature until it sits on the line.
5. Draw the small marks. Use the draw tool for ticks, circles and initials in boxes. Pick a thin brush and a dark color. The eraser removes your own strokes if a tick lands in the wrong box.
6. Add what is missing. Insert an image such as a company logo or a stamp, or add a blank page or a photo page when the sender asks for an extra sheet, like a copy of a receipt.
7. Save and share. Saving writes your text, drawings, images and signatures into the PDF, so any PDF app shows them the same way. Then share the file through Mail, Messages, AirDrop or Files.

The part people get wrong: text that floats

Text that floats above the line or runs into the printed label is the most common problem. It happens when you place the text box at normal zoom and never check it up close.

After you type, zoom in until the printed line fills a third of the screen, then drag the box so the letters sit 1–2 mm above the line. Do the same for the signature: the lowest stroke should touch the line, not the text under it.

Files app Markup vs a PDF editor app

The free choice is already on your phone. Apple's Files app opens PDFs with Markup, and Apple's guide explains how to fill out forms, sign documents and create signatures: tap a blank field and type, use AutoFill from your contact card, add a text box, and add a signature that iPhone saves for next time. The Markup text tools also let you change the font, size and color of a text box and add shapes and stickers.

Which one to pick

Pick Markup in the Files app when a PDF has real form fields and you need to fill it once; it is the fastest way to edit a PDF on iPhone for free. Pick a PDF editor app when you sign and fill papers often, when the PDF is a scan with no fields, or when you want the paper and the signed copy in one library. MRS covers the full loop on one iPhone: scan the paper, type on it, sign it, save it and find it again later by a word inside it.

When to type, when to sign, when to draw

The rule is short: type what must be read exactly, sign where the law or the sender asks for a signature, and draw only small marks.

Type names, addresses, dates, account numbers and amounts. Typed text stays sharp at any zoom, and the recipient cannot misread a 7 as a 1. Handwriting with a finger on a small screen is slower and harder to read, so the classic mistake is drawing your address letter by letter.

Sign only on the signature line, and never type your name there. A typed name where a signature belongs tells the reader you did not sign.

A drawn signature is an image of your handwriting on the page. An electronic signature is a legal concept, and a certificate-based digital signature is a separate cryptographic tool. Everyday forms usually accept a drawn signature; when a contract asks for a certificate-based one, use the service the sender names.

Draw ticks, circles and initials. A tick in a checkbox reads better drawn than typed as an "X", and a quick circle around "Yes" is clearer than a text note.

Match the text to the printed form

Printed text around the field tells you the size and style to copy. Most forms use 10–12 pt text, so start at 12, the smallest size in MRS, and go up only for large boxes.

Use one font for the whole document: Helvetica for modern forms, Times New Roman for older letters and contracts. Keep the color black unless the form asks for blue ink; blue is common only for signatures.

Line up everything you type on the same left edge. If the form has a column of fields (name, street, city), start each answer at the same distance from the label. This takes 30 seconds and makes the page look typed on a computer.

How to check an edited PDF before you send it

A two-minute check catches almost every problem before the recipient does. Open the saved file again, outside the editing screen, and look for these signals:

• Every field filled: did you answer each question, including the date next to the signature?
• Text on the lines: at full zoom, does each answer sit on its line without touching the printed label?
• Signature placed: is the signature on the signature line, the right size, and on every page that asks for one?
• Pages in order: is an added page, such as a receipt copy, where the sender expects it?
• Readable on another screen: does the file look the same when you open it from Mail or the Files app?

A workable test: read it like the recipient

Reading it like the recipient means you send the finished PDF to yourself first, then read it top to bottom at normal size, the way the landlord or the school office will.

If you have to zoom in to read an answer, the text is too small; if an answer looks crowded, the box is too close to the label. Fix it once, save, and send the real email.

Common mistakes when you edit a PDF on iPhone

• Mistake: typing your name as a signature. It looks unsigned. Use the signature tool and draw it once; the saved copy makes it fast next time.
• Mistake: drawing text with your finger. It is slow and hard to read. Use the text tool for anything longer than your initials.
• Mistake: placing text at full zoom-out. The box lands a few millimeters off. Zoom in on each field before you drop text.
• Mistake: mixing fonts and sizes. Three fonts on one form looks improvised. Pick one font and one size and keep them.
• Mistake: sending before you reopen the file. A missed date or a box on the wrong page goes out with the email. Reopen the saved PDF and check it first.

Edge case: a PDF you need to reword

A PDF you need to reword has a sentence to change, not a blank to fill: a wrong date in a contract or a typo in an invoice. Phone editors add content on top of the page and do not rewrite the original text of the PDF.

A white box over the old words with new text on top can look fine on screen, but the old words can still sit in the file underneath. The honest fix is to ask the sender for a corrected PDF, or to edit the source document (Word, Pages, the invoicing tool) and export a new PDF.

Your PDF editing checklist

• Right tool per field: typed text for facts, a signature on the signature line, drawn marks for ticks and circles.
• One font, one size: 12 pt black in a plain font unless the form says otherwise.
• Zoomed placement: every answer and the signature sit on their lines at full zoom.
• Saved signature: drawn once, reused on every document.
• Reopened and checked: the saved PDF read once more before it leaves your phone.

When you fill and sign papers every week, it pays to keep the paper, the edited PDF and the signature in one place. MRS does that on your iPhone: download it, see all features on the home page, read who makes MRS, or ask a question on the support page.