PDF to Long Image renders every page of a single PDF locally, stacks the rendered pages from top to bottom on one continuous white canvas, and lets you download the result as a single lossless PNG. Although the converter handles one PDF per job, you can rerun it on additional files in quick succession to produce a separate long image for each document without the files ever leaving your browser. The "multiple files at once" idea here really means two things working together: a single PDF can contain many pages that all merge into the tall image, and several PDFs can each be processed back to back through the same in-browser pipeline. Because rendering, stacking, encoding, and download creation all run on your own device, no document is uploaded to a server, and a newer job will cancel any older one that is still running. The result is a single image/png file with a name derived from your PDF, intended for sharing in a chat, scrolling through slides, or pasting where only one picture is accepted.
What "Multiple Files at Once" Means Here
If you arrived looking for a tool that accepts a queue of PDFs and returns many long PNGs in a single click, this converter takes a slightly different approach. PDF to Long Image is built around one file per run, so the way it actually handles a batch of documents is by being fast and isolated: load PDF A, convert, download, load PDF B, convert, download, and so on. No document is uploaded between those runs, and the previous file is released from memory once you choose a new one.
Two readings of "multiple" both fit the tool. The first is many pages inside a single PDF, which is what the stack actually merges. The second is many separate PDF documents, each of which becomes its own tall PNG after a quick repeat run. Each run enforces the same private, in-browser pipeline: the PDF never leaves your device, the rendering worker is shared with the other PDF image converters for faster caching, and the final canvas is calculated end to end before a single byte of the PNG is encoded.
Convert Each PDF to a Long PNG
The same six actions work for every PDF in your batch, so the steps below double as the workflow for the entire folder.
- Open the PDF to Long Image tool and choose one PDF up to 25 MiB from your device.
- Pick a rendering scale and a page gap between 0 and 32 pixels that separates neighboring pages with a white strip.
- Click Convert to Long PNG; the tool preflights every scaled page viewport and the full combined canvas before encoding begins.
- Read the combined width, total height, and page count shown in the preview so you know exactly how large the result will be.
- Download the single lossless PNG named after your PDF with a -long.png suffix.
- To handle the rest of your batch, pick another PDF in the same browser tab and repeat from step 2.
The preflight step is what makes a long image workflow different from converting page by page. The tool calculates the scaled viewport of every page, the centered position of narrower pages inside the widest-page canvas, the exact gap sum, the total height, and the overall pixel area before any PNG encoding runs. If those numbers fall outside the safety limits, an error message appears and no partial long image is produced. This layered rendering and canvas composite approach is standard page-rendering practice in the Mozilla PDF.js project, after which the combined canvas is handed to the lossless PNG encoder through HTMLCanvasElement.toBlob.
Choosing Scale and Page Gap
Two settings govern how the long PNG looks before you press Convert, and the right pick depends on how the image will be consumed.
Scale changes the raster dimensions of every page before the pages are combined. Raising scale can make small text and line art clearer when the long image is opened at full size, but width, height, memory use, and download size grow quickly. Lowering scale keeps the file compact and reduces the chance of hitting the pixel limits described further down. For a quick share in a chat, a moderate scale is usually enough; for archival or zoom-and-read use, a higher scale is worth the extra size.
The gap is a user-selected strip of white pixels between 0 and 32 wide that separates each pair of neighboring pages. A small gap keeps the strip tight for a continuous scroll, while a wider gap acts as a visual page break that makes long documents easier to navigate. Neither the gap nor any side margin carries content; both are filled with white pixels and become part of the final image.
One other visual rule is enforced automatically: when pages have different sizes, the widest rendered page sets the canvas width and narrower pages are placed horizontally in the center without stretching. A landscape slide next to portrait text will therefore keep its original proportions even though they live on the same final canvas.
Safety Limits You Need to Check Before Converting
The same preflight that calculates the canvas also enforces hard limits, so reading them once helps you design a batch that converts cleanly.
| Boundary | Cap |
|---|---|
| Source PDF | 25 MiB; up to 40 pages |
| One rendered page | 12,000 pixels per side; 40 megapixels |
| All page renders combined | 100 megapixels total |
| Final long image canvas | 12,000 pixels per side; 100 megapixels |
A long document can reach the height ceiling even when every individual page is small, because the rendered heights plus gaps stack. The simplest fixes when the preflight refuses a PDF are to lower the scale, drop the gap toward zero, or export the pages as separate files instead. For deeper guidance on which knob to turn when one of these caps fires, the guide PDF to Long Image on Large Files: Scale and Size Limits walks through these caps with worked examples.
A Worked Canvas Example
To show how the numbers above combine in a concrete run, here is a single calculation written out step by step. Take a 5-page PDF where each page is US Letter at 72 DPI, so every page is 612 by 792 PDF points, and pick a scale of 1.5 with an 8-pixel gap.
Step 1, rendered page dimensions: width 612 × 1.5 = 918 pixels; height 792 × 1.5 = 1,188 pixels. Step 2, gap total between 5 pages: 4 gaps × 8 pixels = 32 pixels. Step 3, canvas width driven by the widest page: 918 pixels. Step 4, canvas height: 5 pages × 1,188 pixels = 5,940 pixels plus 32 pixels of gap = 5,972 pixels. Step 5, total pixels in the final image: 918 × 5,972 = 5,482,296 pixels, or about 5.5 megapixels.
The 5,972-pixel canvas height is well under the 12,000-pixel-per-side cap, and 5.5 megapixels is far under the 100-megapixel aggregate cap, so this stack would preflight cleanly. Any combination that pushes the height or the total pixel area past the caps would instead surface an error and write no PNG at all.
Long Image vs One PNG Per Page vs JPG
The long image format is one of three local PDF-to-image options on this site. The right choice depends on the result you actually need.
| Output goal | Tool | Result shape |
|---|---|---|
| One continuous vertical PNG for scrolling or sharing | PDF to Long Image | Single lossless image/png, all pages stacked, no selectable text or links |
| One separate lossless PNG for every page | PDF To PNG | N separate image/png files, exact output dimensions, suitable for archiving individually |
| Smaller lossy images for email or thumbnails | PDF to JPG Converter | N separate JPEG files with adjustable scale and quality, text becomes pixels |
If the document is meant to be searched, copied, or translated, a long PNG is the wrong format because the converter does not preserve selectable text, live links, form controls, annotations as editable objects, layers, or document metadata. Every page is painted onto the canvas, and the pixels are the only thing in the output.
Filename, Privacy, and Cleanup Behavior
The downloaded PNG carries a name based on your input: leading and trailing whitespace is trimmed, a trailing .pdf in any case is removed, characters that are unsafe on common desktops are replaced, and the suffix -long.png is added. A file originally called meeting-notes.pdf therefore becomes meeting-notes-long.png.
Private handling is built into the pipeline rather than added as an optional step. No PDF is uploaded, the PDF.js rendering library and the shared worker only load once you press Convert, every per-page canvas is released after it has been copied into the long canvas, and the combined canvas plus its object URL are released when settings change, another file is chosen, or the component unmounts. A newer job cancels an older one, so two stacked runs in a row never leave background work behind.
The converter does not bypass passwords, repair damaged files, verify signatures, or assess whether the document is trustworthy; encrypted, corrupted, unsupported, or over-limit PDFs surface as clear errors instead of partial output. The original PDF is never modified by any of this, which keeps the workflow safe to repeat across a folder of unrelated files. Close the tab when the batch is done and every temporary object is gone.
If you're weighing options, PNG to PDF Offline: Convert Locally in Your Browser covers this in detail.