PDF to Long Image turns every page of a single PDF — up to 25 MiB and 40 pages — into one continuous vertical PNG that you can preview, then download and print entirely in your browser, without uploading the document to a server. The pages are rendered top to bottom in their original order, so a ten-page reference becomes one tall image that scrolls in a viewer or prints as a single continuous strip once your output medium supports it. Because the conversion happens locally in your tab, the PDF never leaves your device and the long PNG is the only file produced. The tool paints each PDF page onto its own canvas using the PDF.js rendering engine, then composites those page canvases onto a single final canvas before encoding the result as lossless image/png. That architecture is what makes a single tall image possible — no server processing, no per-page ZIP archive, no manual stitching in an image editor, and no second tool required to combine the pieces.
Printing a long PNG is not the same as printing a PDF. The long image is a single raster — one picture with no selectable text, no live links, and no page breaks — so the workflow suits cases where a continuous visual strip is genuinely what you want: a slide deck you scroll through in chat, a multi-page reference archived as one picture, or a vertical banner that a single print panel can accept. The rest of this guide covers how the dimensions are calculated, what the converter keeps and drops, and the limits that can stop a tall print job before it starts.
Why a Tall PNG Can Be the Right Print Format
Most printers and image editors handle one picture better than they handle a stitched sequence of separate files. When the goal is a single visual artifact — a chat-friendly scroll, a printed poster strip, or an archival snapshot — stacking the pages vertically is the simplest path. A long PNG keeps the original page order, so reviewers see slides or pages in sequence, and the lack of file breaks means there is no seam between adjacent images that might misalign on the printed medium.
The format is also predictable: PNG is lossless, so every pixel of the rasterized page is preserved exactly. That is helpful when the long image contains fine type, line art, or screenshots with small UI text, because lossy formats would smear those details. If your print medium accepts a single tall image — a long-format photo printer, a panel that can be tiled, a chat window that scrolls, or a design tool that imports one PNG per artboard — the long-PNG approach removes the need to manually stitch separate page renders.
How the Output Dimensions Are Calculated
The converter first measures every page in the PDF and applies your chosen rendering scale to each one. The widest rendered page sets the total canvas width, and each page is placed horizontally centered inside that width so that a portrait page does not stretch to match a landscape page beside it. A user-selected gap from 0 to 32 pixels sits between adjacent pages, and the gap area plus any side margins render as white. You see the exact combined width, combined height, and page count in the preview before you commit to the download, so the final canvas size is never a surprise.
As a worked example, an A4 page (595×842 points) painted at scale 1 produces roughly 595×842 pixels. Doubling the scale to 2 yields about 1,190×1,684 pixels per page — that is 1,190 × 1,684 = 2,003,960 pixels, or roughly 2.0 megapixels per page. Twenty such pages stacked with a 4-pixel gap fill 20 × 1,684 + 19 × 4 = 33,756 pixels vertically and 1,190 pixels horizontally, giving 1,190 × 33,756 ≈ 40.2 megapixels of combined canvas — well inside the 100-megapixel cap, but a clear reminder that height grows linearly with page count while megapixels grow as the product of width and height.
How to Convert a PDF to a Long Image Locally
- Open PDF to Long Image in your browser and choose one PDF file from your device — the source must be at most 25 MiB and 40 pages.
- Pick the rendering scale you want and set the gap in pixels between adjacent pages (any value from 0 to 32).
- Click Convert to Long PNG. The tool preflights every page viewport and the full combined layout before encoding, so a document that would exceed the per-page or final-canvas limits is rejected up front rather than producing a misleading partial result.
- Review the reported combined width, combined height, and total page count in the preview, then click Download to save the single long PNG to your computer.
- Open the PNG in your image viewer or print software. If text looks soft at your intended print size, increase the scale and run the conversion again with the same gap setting.
The PDF.js rendering library and its shared worker only load after you press Convert, so the initial page itself stays light. The shared worker URL is reused by other PDF image converters on the site, which lets your browser cache it after the first conversion. The output filename is derived from the trimmed PDF name — a trailing .pdf is removed case-insensitively, desktop-unsafe characters are replaced, and the file ends with -long.png. Starting a new conversion also cancels any older in-progress job.
What Stays and What Disappears in the Long PNG
The long PNG is a page rendering, not a structural PDF conversion. PDF.js paints text, vector artwork, photographs, fonts, clipping paths, and other visible page content onto a canvas, and the converter then draws those page canvases onto one final canvas. What you see on screen is what ends up in the image. The rendering is performed by the open-source Mozilla PDF.js library, which is what gives the tool the same fidelity users see in a typical in-browser PDF viewer.
What does not survive the conversion: selectable text, live links, form controls, layers, annotations as editable objects, document metadata, and the original internal images as separate files. Once the canvas is encoded to image/png, the result is a flat raster. If you need the text to remain copyable, or if the print job depends on hyperlinks and form fields, a different tool — such as a print-ready PDF workflow or a PDF to PNG job that keeps pages separate — is the safer choice.
Comparing the Long PNG With Other Image Outputs
The same page-rendering engine powers three related converters, and the right pick depends on how the output will be consumed. The table below summarizes the practical differences.
| Output | File count | Compression | Best suited for |
|---|---|---|---|
| Long PNG (this tool) | 1 | Lossless | A single scrollable or printable strip where one image is the desired artifact |
| PDF to PNG | 1 per page | Lossless | High-fidelity page-by-page archive or print jobs that prefer separate files |
| PDF to JPG | 1 per page | Lossy | Smaller files when exact pixel fidelity is not required, such as thumbnails or previews |
If your print workflow expects one picture per page — for example, a tool that imports individual page images into a layout program — use the per-page outputs instead. If you want one continuous visual artifact, the long PNG is the only one of the three that delivers it directly.
When the Combined Canvas Hits Its Print-Friendly Limit
Every tool that produces a tall raster has to draw a line somewhere, and this one enforces four hard ceilings. The source PDF may not exceed 25 MiB or 40 pages, any single rendered page may not exceed 12,000 pixels on either side or 40 megapixels, and the combined final canvas may not exceed 12,000 pixels per side or 100 megapixels total. The canvas is rejected before encoding if any of those checks fails, so a document that would have produced a clipped or oversize PNG never makes it to the download step.
| Limit | Value |
|---|---|
| Source PDF size | 25 MiB maximum |
| Source PDF page count | 40 pages maximum |
| Single rendered page | 12,000 px per side, 40 MP |
| Combined canvas | 12,000 px per side, 100 MP |
| Page gap | 0–32 px (user choice) |
The aggregate ceiling is the one most likely to affect print jobs, because a long document can hit the 12,000-pixel height limit even when every individual page is small. When that happens, lower the scale or split the document and export two long PNGs. Every per-page canvas is released once it has been copied onto the combined canvas, and the combined canvas and download URL are released when settings change, another file is chosen, or the component unmounts, so memory stays bounded as the work proceeds.
Quick Checklist Before You Print the Long PNG
Before sending the long image to your printer or layout tool, walk through four checks. First, confirm the combined height in the preview fits your printer or canvas — the tallest panels on a continuous-feed photo printer are usually well under 12,000 pixels, but some image editors cap imported images lower. Second, decide whether you need selectable text; if you do, the long PNG is the wrong format and a real PDF output is the better target. Third, decide whether the page gap should be visible in the print — a 0-pixel gap produces a seamless strip, while a few pixels of white make page breaks obvious.
Fourth, plan your scale: higher scale gives sharper type at full size but expands width, height, memory use, and download size rapidly. A print archive usually wants the highest scale the limits allow; a chat-friendly scroll usually wants a moderate scale to keep the file small. If you find yourself fighting the height limit on a long document, switching to PDF N-Up for tiled printing or exporting pages separately via PDF to PNG is often the cleaner route. Because the conversion is local — the PDF never uploads, and the rendering library only loads after you press Convert — you can experiment with scale and gap settings until the preview matches your print target, without risking the document leaving your device.