PDF to Long Image stacks every page of one PDF into a single vertically-arranged PNG in your browser, producing a tall image whose height equals the sum of the rendered pages plus any gap you choose between them. The conversion is purely visual: PDF.js paints text, vector artwork, and photographs onto per-page canvases, those canvases are then drawn onto one final canvas, and the result is encoded explicitly as image/png so no compression artifacts appear at the seams. The combined image sits on a white background; narrower pages are centered inside a width set by the widest page so they are never stretched, and the entire file is created locally — the original PDF is never uploaded to a server. This is the format to reach for when a single scrollable picture captures the whole document more naturally than a paginated viewer.
What the Long-Image Format Is
The phrase describes the output, not a change to the source. The PDF itself stays exactly as it is on disk; what changes is that every page is rasterized and the resulting pixel rectangles are stacked top to bottom, separated by a white strip whose height you control, inside one PNG file. The first page appears at the top, the last page at the bottom, and the final image opens in any image viewer, chat app, or social platform that accepts PNGs — places where a PDF reader would otherwise be required.
Because the output is a single image, anything that depends on PDF structure is no longer accessible. Selecting text with a cursor, clicking a hyperlink, filling a form field, or extracting the original embedded photographs all stop working once the pages are pasted together and saved as pixels. The long PNG is a presentation format: it preserves how a page looks, not what the page is made of.
Why the Output Is a Single Tall PNG
Three design choices drive the output format. First, vertical stacking matches how people actually scroll a long document on a phone or in a chat thread — top to bottom in one motion, with no tap-to-advance step. Second, PNG is lossless, so the white gap between pages stays a clean white and the original rasterization is not degraded by a second compression pass. Third, the file is built locally: PDF loading, page rendering, canvas composition, and PNG encoding all happen in the browser, so nothing leaves the device. The shared PDF.js worker used for rendering is loaded only after you press the convert button, which keeps the initial page path light and lets the same worker file serve other PDF image converters through the browser cache.
These choices also explain what the tool deliberately is not. It does not produce a structured PDF, it does not preserve selectable text, and it does not output JPG. A separate PDF to PNG tool creates one lossless PNG per page when you want individual files, and a separate PDF to JPG tool creates smaller lossy per-page images when file size matters more than fidelity. Each of those is a different output shape for a different job.
Run a PDF Through the Long Image Converter
- Open the PDF to Long Image converter and pick one PDF from your device, up to 25 MiB and 40 pages.
- Choose the rendering scale and the gap between pages — the gap is selectable from 0 to 32 pixels and the gap area plus the side margins are filled with white.
- Press Convert to Long PNG. The tool first calculates every page's scaled viewport and the complete combined layout before encoding begins, so a partial result is never produced if a later page would push the canvas past a limit.
- Review the reported combined width, height, and page count shown after conversion.
- Download the single PNG. The filename is the trimmed input name with the final .pdf removed case-insensitively, unsafe desktop characters replaced, and -long.png appended. A newer conversion cancels an older one still in progress.
Scale, Gap, and How the Canvas Is Sized
Two controls do almost all of the work. Scale multiplies every page's pixel dimensions before stacking; the gap value controls the white strip inserted between neighbors. The widest rendered page sets the canvas width, and any narrower page is centered horizontally inside that width rather than stretched — so a mix of portrait and landscape pages keeps each page's original aspect ratio.
To make the math concrete, take a five-page PDF whose pages are all US Letter at 612 by 792 PDF points. At scale 2, every page renders to 1,224 by 1,584 pixels (about 1.94 megapixels per page). The combined canvas with zero gap is 1,224 pixels wide and 7,920 pixels tall, totaling roughly 9.7 megapixels. Adding a 16-pixel gap raises the height to 7,984 pixels — four gaps of 16 px added on top of the 7,920 from the pages themselves.
Bumping the same five pages to scale 4 doubles each dimension, producing 2,448 by 3,168 pixels per page and a final canvas height of 15,840 pixels. That exceeds the 12,000-pixel side limit, so the conversion is blocked even though every individual page is well under the per-page cap. This is exactly the failure mode the preflight step is designed to catch: the layout is rejected before any pixel is encoded, leaving the original PDF untouched on disk.
Limits That Can Stop a Conversion
The converter enforces a small set of hard limits so a runaway document cannot lock up the browser tab. The table below lists every guardrail and the value the tool applies.
| Limit | Value |
|---|---|
| Source PDF file size | 25 MiB maximum |
| Source PDF page count | 40 pages maximum |
| One rendered page, per side | 12,000 pixels maximum |
| One rendered page, area | 40 megapixels maximum |
| All pages combined, area | 100 megapixels maximum |
| Final combined canvas, per side | 12,000 pixels maximum |
| Final combined canvas, area | 100 megapixels maximum |
A long document can reach the height limit even when every individual page is small, because the final canvas height is the sum of all pages plus gaps. The fix is the same in every case: lower the scale so each page rasterizes to fewer pixels, or export pages separately with a per-page converter. Encrypted, damaged, unsupported, or over-limit documents show an error rather than a partial result, and the tool never bypasses passwords, repairs PDFs, verifies signatures, or assesses whether a document is trustworthy.
What the Long PNG Keeps and What It Drops
The output is a pixel rendering, not a reauthoring of the PDF. Knowing which properties survive the trip and which do not is the fastest way to decide whether this tool is the right tool for the job.
| Property | Status in the long PNG |
|---|---|
| Visible page layout and artwork | Preserved as painted pixels |
| Text appearance and typography | Preserved as painted pixels |
| Photographs and raster images on the page | Preserved as painted pixels |
| Vector scalability beyond chosen scale | Lost — output is a fixed-resolution raster |
| Selectable text layer | Lost |
| Live hyperlinks | Lost |
| Form controls and widgets | Lost |
| Annotations as editable objects | Lost |
| Layers | Lost |
| Document metadata (title, author, etc.) | Lost |
| Original embedded images as separate assets | Lost |
Every per-page canvas is released as soon as it has been copied onto the combined canvas, and the combined canvas plus its object URL are released whenever settings change, another file is chosen, or the component unmounts — so memory pressure stays bounded across multiple conversions in the same session.
When One Tall Image Is (and Isn't) the Right Format
A single tall PNG is the right format for a continuous visual strip: dropping a short reference document into a chat, reviewing a slide deck in one scroll, archiving a multi-page flyer as one picture, or fitting several PDF pages into a slot that accepts only one image. It is the wrong format for anything that needs to remain a real document — printing at high resolution, searching inside the file, filling fields, or sharing with a recipient who needs to keep the original structure. For per-page extraction with selectable text preserved separately, PDF to Text produces a UTF-8 text file; for per-page lossless images, PDF to PNG creates one PNG per page. The PDF on disk is never modified by any of these converters.
Related reading: PNG to PDF Explained: How the Conversion Works.
Related reading: How to Remove Images From a PDF With Acrobat (Locally).