The first page of a PDF as a cover thumbnail, sized right
By the getPDF team · Published 11 October 2026
The short answer
Work back from the size the cover is shown at: a card 300 px wide needs about 600 px of image to look sharp on today’s screens, which is what 72 dpi gives from an A4 page (595 x 842 px). Open PDF to JPG, type 1 in Pages, pick 72 dpi for cards and library rows or 150 dpi for large previews, and keep JPG for photo covers. Drop many PDFs at once and each gives its own cover image.
Try it here, nothing is uploaded
It runs on your device; the PDFs are not uploaded anywhere, which matters for unpublished catalogues and course material.
Work backwards from the displayed size
A thumbnail is shown at a fixed width in your layout, in CSS pixels. Screens with high pixel density draw more than 1 device pixel for each CSS pixel: MDN Web Docs gives 2 as the expected value for HiDPI and Retina displays, and more than 2 for many phones (checked on 11 October 2026). So:
image width = displayed width x 2. A 300 px card wants a 600 px image; a 150 px library row wants 300.
Then pick the DPI whose pixel width gets there. For an A4 page (8.27 inches wide) that is 72 dpi for 595 px and 150 dpi for 1240 px; for US Letter, 612 and 1275 px. Anything bigger is bytes your visitors download and never see.
Steps
- Drop the PDF into PDF to JPG above. For a catalogue, drop all of them at once.
- Type
1in Pages. Only the first page is drawn and the rest of the file is not rendered, so a long PDF is about as quick as a short one. - Pick the Resolution. 72 for cards, rows and email, 150 for a large preview or a social preview image.
- Set Quality. 85 is the default; a cover shown small can go to 70 with no visible change and a quarter less size.
- Press Make the images and download. One file gives one image; several give Download all as a zip, or Save to a folder where the browser supports it.
The image is named after the PDF and the page, padded to the page count: page 1 of a 48-page garden-catalogue.pdf becomes garden-catalogue-01.jpg. Name the PDFs after your listings first and the covers match them without renaming.
Our test cover, an A4 report page with a large photo and some text, measured on 11 October 2026:
| Resolution | Pixels | JPG q 60 | JPG q 70 | JPG q 85 | PNG |
|---|---|---|---|---|---|
| 72 dpi | 595 x 842 | 59 KB | 67 KB | 91 KB | 188 KB |
| 150 dpi | 1240 x 1754 | 285 KB | 658 KB |
Sizes per destination
| Destination | Shown at | Image to make | DPI from A4 | Format |
|---|---|---|---|---|
| Shop or course product card | about 300 px wide | about 600 px wide | 72 (595 px) | JPG, quality 70 to 85 |
| Document library or intranet row | about 120 to 160 px wide | about 300 px wide | 72, then shrink in your CMS | JPG |
| Email header or newsletter tile | your template’s column width | twice that width | 72 or 150 | JPG |
| Social preview (og:image) | 1200 x 630 recommended by Meta | 1200 x 630, landscape | 150, then crop | JPG |
| Large preview on a product page | 600 px wide or more | 1200 px wide or more | 150 | JPG for photos, PNG for text covers |
The social preview is the awkward one: an A4 cover is portrait and the preview is landscape, 1.91:1 (Meta for Developers, “Images in Link Shares”, checked on 11 October 2026). 2 ways to get there:
- A band of the cover. In Crop PDF, choose By margins and keep a 107 mm tall strip of the page (for example Top 0, Bottom 190): at 150 dpi that works out at 1240 x 632 px, which your CMS or an image editor trims to 1200 x 630.
- The whole cover on a canvas. Render page 1 at 72 dpi (595 x 842 px) and place it on a 1200 x 630 background in any image editor, with the title next to it.
getPDF draws pages at the DPI you choose; it does not resize to an exact pixel size or add a canvas. That last step belongs in your shop or CMS, which usually resizes uploads anyway, or in an image editor.
Many PDFs: a whole catalogue in 1 run
Karol Michał runs a small shop in Łódź with 20 garden guides as PDFs. He drops all 20 into PDF to JPG, types 1 in Pages, picks 72 dpi and quality 80, and presses Make the images. Each PDF gives 1 cover named after it; Download all (20) as zip saves them together, ready to upload next to the listings.
If the shop wants a short sample PDF next to the cover instead of an image, Extract pages cuts the first pages into a small PDF of their own, with the text still selectable.
Extract pagesSelected pages to a new file. Free, runs on your device.The honest part
A thumbnail is decoration. Search engines and screen readers learn nothing from a picture of a cover, so:
- Write alt text that says what the document is (“Cover of the 2026 garden guide, 48 pages”), not “thumbnail”.
- Link the PDF next to it, with its title and size in text, so people and search engines can reach the document itself.
- Keep the cover small. A product grid of 30 cards at 285 KB each is 8.5 MB before anyone scrolls; at 67 KB it is 2 MB.
And a cover that is mostly small text never reads well as a thumbnail, whatever the DPI. Put the title in the listing as text and let the picture show the look. More on picking DPI in PDF to image DPI; every other route out of a PDF is in the pillar, PDF to images.
Questions
What size should an og:image be?
Meta recommends at least 1200 x 630 px, close to 1.91:1 (Meta for Developers, checked on 11 October 2026). An A4 cover is portrait, so render it at 150 dpi (1240 px wide) and crop a 1.91:1 band from it, or place the cover on a 1200 x 630 canvas in an image editor.
JPG or PNG for a cover?
JPG for covers with photos: our photo cover at 72 dpi is 91 KB as JPG and 188 KB as PNG. PNG for covers that are mostly text or flat colour, where it is often the smaller file and keeps the title crisp.
Can I make covers for many PDFs at once?
Yes. Drop all the PDFs into PDF to JPG, type 1 in Pages, and press Make the images. Each file gives 1 image named after it, and Download all saves them as 1 zip.
Why does my thumbnail look soft on a phone?
Phones and most laptops draw 2 or more screen pixels per CSS pixel. A card 300 px wide needs about 600 px of image to look sharp there. 72 dpi gives 595 px from an A4 page; for bigger cards use 150 dpi.
The tools for this job
Keep reading
- PDF to images: get JPG or PNG out of any PDFTurn PDF pages into JPG or PNG on your device: pick the format, set the DPI, convert only the pages you need.
- PDF to image DPI: 72, 150 or 300, and what each is forPick the right DPI for PDF to JPG or PNG: 72 for thumbnails, 150 for screens, 300 for print.
- Convert specific PDF pages to JPG, and skip the restConvert only certain PDF pages to JPG or PNG: type single pages or ranges like 2, 5-7 and skip the rest.
- Turn a PDF into one long image, and when one image is the wrong ideaTurn a multi-page PDF into 1 image for chat or notes: convert the pages to JPG and stack them, or put several pages on 1 sheet.
- PDF to JPG or PNG: which format to pick, with real sizesJPG is smaller for photo pages, PNG keeps text sharp and can be transparent.
- Insert a PDF into an email body, so people see it without opening anythingShow a PDF inside the email itself: turn the page into an image, put it in the body, attach the PDF for printing.