Post a PDF to Instagram or WhatsApp, as images people can read

What each app does with your picture

The apps decide how your page looks, so start with their rules. These come from Instagram’s and WhatsApp’s own help pages, checked on 11 October 2026.

Where it goes	What the app wants	What happens otherwise
Instagram feed post	up to 1080 px wide, shape between 1.91:1 and 3:4 (1080 x 566 to 1080 x 1440)	wider images are shrunk to 1080; taller shapes are cropped
Instagram carousel	up to 20 photos and videos, one shape for all of them	the shape you pick applies to every image in the post
Instagram story	the help pages give no size; Meta’s ads guide recommends 9:16 at 1440 x 2560	a page of another shape shows with space around it
WhatsApp photo	Standard quality, or HD quality when you tap HD	Standard quality makes the picture smaller
WhatsApp document	any file up to 2 GB, sent as it is	not recompressed; the person opens it like any file

Two things follow. An A4 page is taller than 3:4 (its shape is about 1:1.41), so Instagram cuts a strip off it unless you crop it yourself, and you would rather choose which strip. And a US Letter page (1:1.29) already fits: it goes up whole.

Step 1: crop the page to Instagram’s shape

Crop PDF sets a new visible edge for each page; nothing is redrawn, so the text stays sharp. Choose By margins and type how many millimetres to take off each side. For an A4 page, 210 x 297 mm:

Shape you want	Take off (total, top plus bottom)	Result at 150 dpi
3:4 portrait, the tallest Instagram keeps	17 mm, for example 8.5 top and 8.5 bottom	1240 x 1654 px
4:5 portrait	34.5 mm	1240 x 1550 px
square	87 mm	1240 x 1240 px

We measured the 3:4 and square rows by cropping a test invoice and converting it. If the important part of the flyer sits near the top, take the whole amount off the bottom instead.

Trim white margins, the other crop mode, cuts each page to what is printed on it plus a few millimetres (3 by default, set under Keep around). That makes the text bigger in the post, but the shape follows the content: our test invoice came out 1027 x 1035 px, nearly square. Trim first, then check the shape in the result.

Crop PDFTake millimetres off each side, or trim the white margins. Free, runs on your device.Open

Step 2: convert the pages to JPG

1. Drop the cropped PDF on the converter at the top of this page, or tap Choose files on a phone.
2. Set Resolution to 150. An A4 page becomes 1240 px wide, just over Instagram’s 1080, so Instagram only scales down and never blows a small picture up. 300 dpi gives 2480 px, which Instagram throws away.
3. Leave Quality at 85. Our test invoice came out at 167 KB at 150 dpi; quality 95 gives 221 KB with no difference you can see on a phone.
4. Pick the pages. Leave Pages on all, or type the ones you want, such as 1, 3.
5. Press Make the images and download. Several pages come as a zip, named flyer-jpg.zip for flyer.pdf. On a phone, switch Several pages to “as separate files” first: each page then gets its own Download button and you skip the unzipping. The phone guide shows where the files land on iPhone and Android.

Step 3: post it, in the right order

For a carousel, open Instagram, tap the new post button, tap the option to select several, and pick the images in page order. Files are named by page number (flyer-1.jpg, flyer-2.jpg; with 10 pages or more the numbers are padded, flyer-01.jpg), so the order is easy to follow. Instagram’s help says the shape you choose applies to every image in the post, which is why all pages should get the same crop. If the order comes out wrong, you can fix it after posting: the three-dot menu, Edit, then long press to reorder.

For WhatsApp, attach the image as a photo and tap HD before sending; Standard quality shrinks it. To make HD the default, WhatsApp’s help names Settings, Storage and data, Media upload quality. HD is not available for status updates, so a status always gets the smaller version.

Can people read it on a phone?

This is where most PDF posts fail, and the arithmetic shows why. A phone shows a feed post about 390 to 430 screen points wide (an iPhone 15 is 393). Shrink a whole A4 page to that width and 10 pt body text ends up about 6 points tall on screen, roughly a third of the size of the phone’s own text. Nobody zooms into a feed post to read it.

So post the part that matters, big:

• Crop to the key block. A menu’s prices, the date and place of an event, the 3 lines of an announcement. By margins with large numbers cuts a strip out of the page; convert that strip and it fills the post.
• Split a dense page. A page with 2 halves becomes 2 carousel images: crop the top half once, the bottom half once (run the crop twice on the same file with different margins), and convert both.
• Let the caption carry the detail. Opening hours, the address and the link belong in the caption, where they are text and can be copied.

Jana Čermák posts the Graz choir’s concert flyer: a portrait A4 page with a photo on top and the details below. Cropped to 3:4 the whole flyer fits, but the small print is unreadable; the second carousel image is the details block alone, cropped to a square, and that one people can read.

The honest part: when an image is the wrong format

An image is a poster of the page, not the page. Text in a JPG cannot be selected, searched or copied, links stop working, and a screen reader finds nothing in it unless you write alt text for it.

For anything someone has to print, fill in, sign or read in full (a price list for a shop, a form, a timetable), send the PDF itself. On WhatsApp, attach it as a Document: up to 2 GB, delivered byte for byte, not recompressed. Post the image as the teaser and the PDF as the thing people keep.

getPDF does not offer Instagram crop presets or a story layout: you type the millimetres for the shape, as above, and it has no option to place a page on a 9:16 background. If you need a designed story, an image editor or Instagram’s own story editor does that part better. For the general choices between JPG, PNG and the DPI settings, see PDF to images; to convert only some pages, see converting specific pages. Everything on this page runs in your browser, so a flyer with names and phone numbers on it is never sent anywhere before you choose to post it.