PNG to PDF
Convert PNG images into a single PDF document with lossless quality. Transparency is preserved and metadata is stripped. Files are processed in your browser — they never leave your device.
PNG to PDF converts PNG images into a single PDF document using pdf-lib running in your browser via a Web Worker. The conversion is lossless — pixel data is preserved bit-for-bit and PNG transparency is honored in the output PDF. Drop up to 30 PNGs (25 MB each), reorder them, pick A4 / Letter / Fit-to-image and margin, then click Create PDF. Metadata chunks (tEXt, iTXt, eXIf) are stripped automatically.
What is PNG to PDF?
PNG to PDF takes one or more PNG images — typically screenshots, design exports, charts, diagrams, or graphics with transparency — and packs them into a single PDF document. Each PNG becomes one page (or several per page if you enable that), sized to A4, US Letter, or fitted exactly to the image. Because PNG is a lossless format, the output PDF retains every pixel exactly as it was in the source — no JPEG artifacts, no compression bleed.
Most online "PNG to PDF" services upload your images to a remote server, then often re-encode them as JPEG to shrink the result — losing the lossless property that made PNG worth using. This tool runs the entire conversion in your browser and keeps PNGs as PNGs inside the PDF, so quality is identical to the source. Files never cross the network.
How does the in-browser conversion work?
Pikowl loads each PNG into a Web Worker — a background thread inside your browser. The worker decodes each file using createImageBitmap, draws it onto an OffscreenCanvas, then re-encodes it back to PNG. That round-trip is lossless for the pixel data but drops the original tEXt, iTXt, zTXt, and eXIf chunks. The cleaned PNG bytes are embedded into a PDF using pdf-lib's embedPng path, which preserves the alpha channel. The finished PDF is offered as a downloadable Blob via URL.createObjectURL. Nothing is sent to any server.
Is it safe to convert sensitive PNGs here?
Yes. Open the network tab in DevTools while you use the tool — you will see no outbound requests during the conversion. Images are read locally via the File API, processed in a sandboxed Web Worker, and the resulting PDF lives only in your browser's memory until you download it. Closing the tab discards everything. PNG screenshots often contain sensitive UI like account numbers, internal tools, or chat windows; keeping the conversion local matters.
What metadata gets stripped from PNGs?
PNG files can carry several ancillary chunks: tEXt and iTXt for textual metadata (often holding the editing software's name and version), tIME for the last-modified timestamp, eXIf (added in PNG 1.5) for EXIF blocks copied from the source camera, and iCCP for color profiles. Because Pikowl re-encodes each PNG via canvas, all of these chunks are dropped — only the IHDR (header), IDAT (pixel data), and PLTE/tRNS (palette/transparency) chunks survive. The output PDF embeds clean PNG bytes with no editing history or timestamps.
What are the limits and why?
Up to 30 PNGs per conversion, 25 MB per file, with a soft warning at 100 MB combined and a hard cap at 150 MB. PNG file size scales with image dimensions and color complexity — a 4K screenshot of a flat UI compresses to a few MB, but a 4K screenshot of a photo can hit 30+ MB. Decoded bitmaps occupy roughly 4× the pixel count in memory (RGBA), so a 4K PNG decodes to ~33 MB working set. Mobile Safari can crash uncatchably above ~200 MB. For larger batches, convert in two passes and merge with our Merge PDF tool.
How does Pikowl compare to Smallpdf and iLovePDF for PNG-to-PDF?
The substantive differences are processing location, output quality (lossless vs. lossy re-encode), daily-use limits, and pricing. Numbers below reflect the public free-tier offers from each service as of April 2026.
| Feature | Pikowl | Smallpdf | iLovePDF |
|---|---|---|---|
| Where files are processed | Your browser | Remote server | Remote server |
| Sign-up required | No | Optional | Optional |
| Output quality | Lossless · transparency preserved | Re-encoded as JPEG | Re-encoded as JPEG |
| Max file size (free) | 25 MB | 5 MB | 200 MB (combined) |
| Price | Free | $9/mo for unlimited | $7/mo for premium |
Sources: smallpdf.com/pricing and ilovepdf.com/pricing, retrieved April 2026.
Common Uses
- Screenshots: Bundle a sequence of step-by-step screenshots (Cmd+Shift+4, Print Screen, Snipping Tool) into one PDF for documentation, bug reports, or tutorials.
- Design exports: Combine multiple Figma / Sketch / Photoshop PNG exports into a single PDF deliverable for client review.
- Logos and branding assets: Package transparent-background logo PNGs into a brand-guideline PDF that preserves the alpha channel.
- Charts and diagrams: Combine PNG-exported graphs from spreadsheet tools or Mermaid renderings into one PDF for a report.
- Architecture and UI mockups: Stitch together pixel-perfect PNG screens of an app or floor plan into a single review document.
- Course materials: Compile slide PNG exports or whiteboard captures into one PDF for offline study.
FAQ
Are my PNGs uploaded to a server?
No. The conversion runs entirely in your browser — open DevTools' network tab and you'll see no outbound requests during the process. PNG files are read from your disk via the File API, processed in a Web Worker, embedded into a PDF using pdf-lib's embedPng, and offered back as a download. Nothing leaves your device.
Is the conversion really lossless?
For pixel data, yes. Each PNG is decoded into a raw bitmap, drawn to a canvas, and re-encoded as PNG — a round-trip that preserves every pixel exactly. The output PDF then embeds those PNG bytes via pdf-lib's embedPng path, which keeps the alpha channel and all color values intact. The only thing dropped is the metadata chunks (tEXt, iTXt, eXIf, tIME) — the actual image is bit-identical at the pixel level.
Does PNG transparency show up in the PDF?
Yes. PDF supports image transparency natively, and pdf-lib's embedPng preserves the alpha channel. Wherever your PNG had transparent or semi-transparent pixels, the PDF will show whatever is behind on the page (which is white by default, but can be a colored background or another image if you stack them). For brand assets like logos, this means the PDF version still works on dark or colored backgrounds.
Why is my screenshot PNG so large?
PNG is lossless, so file size scales with how complex the pixels are, not with how clean the image looks. A solid-color screenshot compresses tiny; a screenshot containing a photo or anti-aliased text in many colors can be huge. If you need smaller PDFs and lossless quality isn't important, save the screenshot as JPG first and use the JPG-to-PDF tool — JPG handles photographic content far more efficiently.
Why is this tool PNG-only? I have JPGs too.
We split image-to-PDF by format so each tool can be tuned correctly. PNG goes through a lossless round-trip; JPG goes through a quality-0.92 JPEG re-encode. Mixing them in one tool would force a single quality model on both. For mixed batches, convert each set with the right tool and combine the resulting PDFs using our Merge PDF tool.
Will the file size of my PDF be large?
It depends on the source PNGs. Each PNG is embedded into the PDF more or less as-is, so the PDF is roughly the sum of the input file sizes plus a small overhead. PDFs with many large lossless screenshots can easily exceed 50 MB. If file size matters more than lossless fidelity, consider exporting your sources as JPG first.
How is the page order set?
Use the drag handle (the dotted icon on the left of each row) to drag a PNG up or down. On mobile, press and hold the handle, then drag. The PDF will arrange pages in exactly the order shown in the list, top-down. Filenames are visible in the on-screen list but are not embedded in the PDF metadata.
By the Numbers
- PNG was standardized as ISO/IEC 15948 in 2003 (originally W3C 1996), designed as a free-of-patents replacement for GIF — and remains the dominant lossless format for screenshots, UI mockups, and graphics with transparency.
- PNG file format supports up to 16 bits per channel with full alpha-channel transparency, which is why design tools and screenshot utilities default to PNG when fidelity matters more than file size (W3C PNG Specification).
- 97% of browsers (Can I Use, 2026) support OffscreenCanvas — the off-main-thread image API this tool uses — so even high-resolution PNG batches process without freezing the page.