Convert PNG to PDF Online Free – Transparency and Layout Preserved
Combine PNG diagrams, screenshots and logos into one PDF without flattening their transparency to white. The PNG data is embedded losslessly, the pages can be ordered before saving, and the whole job runs in your browser.
PNG data is embedded losslessly and its alpha channel stays as a PDF transparency mask. A transparent logo will not get a white box behind it.
Drop PNG images here to build a PDF
Click to browse, drag and drop, or paste from clipboard
Accepts .png files. Add several to make a multi-page PDF, then reorder them. Processed in your browser.
Larger selections show a memory caution you can skip. Our measured laptop runs completed up to 100 MB for tools like this; phone browsers warn earlier.
Selected images (0)
0 KB total
Network requests reported while processing: 0
Counted during an automated browser test that processed a real file, excluding the page's own HTML, CSS, and script downloads. Saved in docs/test-results/png-to-pdf.json.
How to use PNG to PDF
- 1 Drop one or more .png files into the workspace.
- 2 Reorder or remove images until the page sequence is right.
- 3 Pick Fit image dimensions to match each image, or Standard A4 to centre it on a standard page.
- 4 Click Convert to PDF and download the finished document.
What it does — and what it doesn't
Each PNG is embedded directly with pdf-lib. When the image has transparent pixels, its alpha channel becomes a PDF soft mask rather than a white background; an image with no transparency is stored without a mask. 16-bit PNGs are embedded at 8 bits per channel. The page around it is either the image size in points or an A4 page in the matching orientation with half-inch margins. The PDF is serialised in local memory, so no image bytes or document contents are transmitted.
Limits and browser boundaries
- This route accepts PNG files only. Dropping a JPG or WebP shows the format error instead of converting it.
- Lossless embedding can make the PDF much larger than the same images saved as JPEG, especially for photos.
- No OCR or text layer is added. Text inside screenshots stays part of the image.
- Fit pages use the image pixel count as PDF points, so very large screenshots produce very large pages; A4 is better for printing.
- Transparency is preserved as a PDF mask, not as a checkerboard. Most viewers show the page white behind it, and some older viewers may render it differently.
- Animated PNGs are rejected with a clear error instead of silently converting one frame.
- A PNG with no transparent pixels is stored without a soft mask, and 16-bit inputs are embedded at 8 bits per channel.
- Memory caution: selections above 100 MB show a warning you can skip, and phone browsers warn earlier. No hard size cap.
Measured on our test files
Real numbers recorded in automated browser tests, saved in docs/test-results/png-to-pdf.json.
| Fixture / Scenario | Input | Output / Result | Duration |
|---|---|---|---|
| PNG to PDF (Fit layout, 3 PNGs)sample-transparent.png + png-palette.png + png-16bit.png | 764 B | PDF nimbzo-png-to-pdf.pdf 3 pages • 3.1 KB | — |
Client-Side Privacy Proof
All computation executes strictly inside your device CPU and GPU memory. Your file bytes, photos, and document text are never uploaded or transmitted to any server.
Verify it yourself in 5 seconds:
- Press F12 (or right click → Inspect) and switch to the Network tab.
- Drop your file into the tool above and click process.
- Confirm that zero outbound requests or file payloads leave your computer.
Frequently asked questions
Is PNG transparency preserved in the PDF?
Yes. The alpha channel is embedded as a PDF soft mask, so a transparent logo keeps its shape instead of being flattened onto a white rectangle. The page background you see depends on the PDF viewer; most render it as white.
Can I put several PNG images into one PDF?
Yes. Add a batch, reorder the pages with the arrow buttons, and convert once. Each image becomes one page, and the result reports the total page count and file size.
Why is the PDF larger than the PNG files?
PNG is already lossless, and the PDF stores each image plus page objects. Unlike a JPEG-to-PDF conversion, there is no lossy re-encoding to reduce the size. For photo-heavy documents, converting to JPEG first may produce a smaller PDF at some quality cost.
Should I use Fit or A4?
Fit keeps the page identical to the image dimensions, which suits diagrams and screen captures. A4 centres the image with margins and picks portrait or landscape from the image, which suits documents meant to be printed or read page by page.
Are my PNG files uploaded to a server?
No. The images are embedded and the PDF is built inside the browser tab. You can confirm with the Developer Tools Network tab; there is no account requirement or watermark.
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