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Convert PNG to PDF free, without uploading
PNG to PDF stores the picture as a JPEG on one page, so photos shrink a lot (our portrait: 4.46 MB PNG → 254 KB PDF, −94%) while a flat chart barely changes (39.7 KB → 40.3 KB). Transparent areas turn white; keep the quality high for text and signatures. Nothing is uploaded.
PNG to PDF
PDF · no file-size limit · original pixel size · white background
No file-size limit is set: PixelFit saves at high quality and changes only the format and any pixel size you set.
Fit, background and padding white background · page the size of the picture
Saving presets is part of Pro.
The result appears here: the exact byte count, pixel size and quality, the size before and after, a preview and a download button.
The batch kit (one ZIP for up to 500 photos, several photos merged into one PDF) is part of Pro.
What changes from PNG to PDF
5 of these 6 points lose or alter something on the way from PNG to PDF; the rest carry over.
- Lost or changed: PDF pages from PixelFit hold a JPEG image, which cannot store transparency, so transparent areas of the PNG are filled with a background colour (white unless you pick another).
- Lost or changed: Animated PNGs (APNG) are rare, but if yours is one, only its first frame becomes the PDF.
- Lost or changed: A PixelFit PDF page holds a JPEG, which is lossy: the exact pixels of the PNG are approximated, which is invisible on photos at high quality but can blur sharp text and edges.
- Lost or changed: PNG can hold more than 8 bits per channel (1 to 16 bits per channel); a browser canvas works at 8 bits, so 10-, 12- or 16-bit files are reduced to 8 bits per channel.
- Lost or changed: Metadata is not carried over: the PNG's text chunks, eXIf and ICC data are dropped by the canvas.
- Kept: The PDF is a document with one page per image; the page size follows the pixel size and DPI, so the photo prints at the size you set.
Measured file size: PNG vs PDF
sharp 0.35.5 / libvips 8.18.7, 31 October 2026, long edge 1600 px; PDF saved as PixelFit's PDF writer, one page wrapping the quality 85 JPEG, PNG as lossless, zlib level 6, RGBA.
| Sample | PNG | Change | |
|---|---|---|---|
| portrait photo (1281×1600 px) | 4.46 MB (4,679,548 bytes) | 254 KB (260,507 bytes) | −94% |
| landscape photo (1600×1200 px) | 4.74 MB (4,972,383 bytes) | 641 KB (656,254 bytes) | −87% |
| scanned typed letter (1273×1600 px) | 2.59 MB (2,714,410 bytes) | 332 KB (339,628 bytes) | −87% |
| flat chart with a transparent background (1600×1000 px) | 39.7 KB (40,653 bytes) | 40.3 KB (41,225 bytes) | +1% |
What the numbers mean for PNG to PDF
Our portrait photo at 1281×1600 px: PNG 4.46 MB → PDF 254 KB (−94%, 18.0 times smaller).
Our landscape photo at 1600×1200 px: PNG 4.74 MB → PDF 641 KB (−87%, 7.6 times smaller).
Our scanned typed letter at 1273×1600 px: PNG 2.59 MB → PDF 332 KB (−87%, 8.0 times smaller).
Our flat chart with a transparent background at 1600×1000 px: PNG 39.7 KB → PDF 40.3 KB (+1%, about the same size).
Per pixel, the portrait took 18.27 bits as PNG and 1.02 bits as PDF, a difference of 4.21 MB on 2,049,600 pixels.
Per pixel, the chart took 0.20 bits as PNG and 0.21 bits as PDF, a difference of 0.56 KB on 1,600,000 pixels.
PDF was smaller than PNG on 3 of 4 samples (portrait photo, landscape photo, scanned typed letter) and larger on the flat chart with a transparent background, so the content of the picture decides.
The PDF is the JPEG plus a little structure: PixelFit's one-page PDF writer added only 729 bytes around the JPEG made from the PNG, so the PDF size is decided by the JPEG quality and pixel size inside it.
How to convert PNG to PDF
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Add the PNG file
Drop the .png file on the tool at the top of this page, tap to choose it, or paste it.
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Pick a background
Choose the colour that fills transparent areas of the PNG in the PDF; white is pre-selected because most forms and documents are white.
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Keep PDF selected
PDF is pre-selected. Add a maximum size in KB if a portal sets one; PixelFit lowers the JPEG quality inside the page until the PDF fits. Our PNG test portrait came out at 254 KB as PDF with no limit set.
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Download the PDF
Save the file ending in .pdf; its size in KB shows before you save.
PNG and PDF side by side
PNG (1996) next to PDF (1993); browser figures checked 31 October 2026.
| Property | PNG | |
|---|---|---|
| File extensions | .png | |
| MIME type | image/png | application/pdf |
| Compression | lossless | lossy or lossless |
| Transparency | yes | yes in general; PixelFit pages are JPEG, so no |
| Animation | yes | no |
| Largest size | 2,147,483,647 px per side | follows the embedded image |
| Colour depth | 1 to 16 bits per channel | whatever the embedded image uses |
| Metadata | text chunks, eXIf and ICC data | document info and XMP |
| First published | 1996 | 1993 |
| Opens in | Chrome, Edge, Firefox, Safari (every current browser); about 97.49% of browsers in use | not read as an image input |
| Good for | screenshots, logos, signatures on white and images with transparency | document uploads, printing and sending several photos as one file |
| Weak for | large photos, which come out several times bigger than a JPEG | profile pictures and web pages, which expect an image file |
| Specification | Portable Network Graphics (PNG) Specification, Third Edition (W3C) | PDF 2.0, ISO 32000-2 (Library of Congress format description) |
When not to change PNG to PDF
- Avoid PDF for screenshots, text, signatures and logos when the destination accepts PNG: JPEG compression softens hard edges, and on our flat chart the PNG to PDF change saved only +1%.
- If the transparent background of the PNG must stay (a logo over a coloured page, a sticker), keep the PNG or choose WebP instead of PDF.
- Do not upload a PDF where the form asks for a photo or signature image: those fields usually check for JPG or PNG, so a PNG photo for such a field should become a JPG instead.
Browser support for PNG and PDF (October 2026)
Reading PNG (.png): Chrome, Edge, Firefox, Safari (every current browser). caniuse puts PNG support at about 97.49% of browsers in use (data updated 29 October 2026).
Writing the PDF: PixelFit's own PDF writer (JPEG page images), every browser. The JPEG inside each page comes from canvas.toBlob, which Chrome 50+, Firefox 18+ and Safari 11+ support (MDN compatibility data, checked 31 October 2026).
Upload forms that ask for PDF
3 of the 61 application portals we checked accept PDF photos, 1 of them with a limit of 50 KB or less. A few of them, for this PNG file (verify with the official notice before you upload):
- Canada G5 sponsorship: PDF photo, up to 4 MB, 420 × 540 px (also takes JPG, PNG).
- Oman eVisa: PDF photo, up to 512 KB (also takes JPG, PNG).
- ICSI student: PDF photo, 20–50 KB (also takes JPG, PNG, GIF, BMP).
Where PNG files come from
PNG files are usually screenshots, exported graphics, scanned signatures or images with a transparent background. Photos saved as PNG are large because PNG keeps every pixel exactly.
Moving a PNG to PDF is mostly about accepted file types and file size.
Sources
- Portable Network Graphics (PNG) Specification, Third Edition (W3C), W3C, checked 31 October 2026: w3.org/TR/png-3/
- PDF 2.0, ISO 32000-2 (Library of Congress format description), Library of Congress, checked 31 October 2026: loc.gov/preservation/digital/formats/fdd/fdd000474.shtml
- caniuse.com “PNG alpha transparency” support table, data of 29 October 2026 (CC BY 4.0): caniuse.com/png-alpha
- Test photo “President Barack Obama.jpg” by Pete Souza (Official White House photo), public domain, measured by PixelFit with sharp 0.35.5 / libvips 8.18.7 on 31 October 2026: commons.wikimedia.org/wiki/File:President_Barack_Obama.jpg
Frequently asked questions
Can I convert PNG to PDF for free?
Yes. The PNG to PDF change runs free on your device, with no sign-up and no upload, one file or up to 25 at a time; Pro raises the batch to 500 with one ZIP download.
How do I convert PNG to PDF?
Drop the PNG on the tool above, keep PDF selected, pick a background colour for transparent areas, and download the .pdf file. Add a KB limit if the destination has one.
Does converting PNG to PDF reduce quality?
A PixelFit PDF page holds a JPEG, which is lossy: the exact pixels of the PNG are approximated, which is invisible on photos at high quality but can blur sharp text and edges. In our test a 1281×1600 px portrait went from 4.46 MB as PNG to 254 KB as PDF (−94%).
Will text and signatures stay sharp in a PDF made from PNG?
Mostly, at high quality. The page holds a JPEG, and JPEG softens hard edges a little at quality 85 (our chart: 39.6 KB) and more under tight limits (32.4 KB at quality 70). For a signature or a form scan, give the PDF the largest KB limit the portal allows.
Why is the PDF so much smaller than my PNG photo?
PNG keeps every pixel exactly, which cost 18.27 bits per pixel on our portrait; the JPEG inside the PDF took 1.02 bits per pixel, and the 729 bytes of PDF structure around it hardly count.
What happens to the transparent background of a PNG?
PixelFit PDF pages hold a JPEG image, and JPEG has no transparency, so transparent pixels of the PNG are filled with the background colour you pick, white by default. Choose PNG or WebP to keep transparency.
Related
More PNG format changes
- PNG to JPG same PNG input
- PNG to WebP same PNG input
Other files to PDF
- GIF to PDF also ends as PDF
- WebP to PDF also ends as PDF
- BMP to PDF also ends as PDF
- HEIC to PDF also ends as PDF
- JFIF to PDF also ends as PDF