How the conversion works
Your PDF is opened in the browser with pdf.js, the open-source reader built into Firefox. Each page you choose is drawn onto a canvas at your resolution and saved as a PNG. With the transparent option on, the canvas starts clear instead of white, so only what the PDF paints ends up in the picture. PNG compression is lossless, so the file holds exactly the pixels that were drawn.
Pixels across = page width in points ÷ 72 × DPI
Pixels down = page height in points ÷ 72 × DPI
Worked example: a company logo for a slide deck
Say the only copy of a logo is on page 1 of a brand-guide PDF, and the page is Letter size, 612 × 792 points. Type 1 in the Pages box, choose 300 DPI and tick Transparent background. The PNG is 612 ÷ 72 × 300 = 2550 pixels wide and 792 ÷ 72 × 300 = 3300 pixels tall. Crop it to the logo in any image editor and it sits on a dark slide with no white box around it.
When the background will and won't be transparent
| Kind of PDF | With the transparent option |
|---|---|
| Exported from Word, Google Docs, PowerPoint or Excel | Usually transparent: these apps rarely paint the paper. |
| Logos, charts and drawings from design apps | Transparent around the artwork, unless the designer added a background shape. |
| Slides with a colored or photo background | The background is part of the slide, so it stays. |
| Scanned documents and phone scans | Solid: each page is a photo of paper, including the white. |
PNG or JPG?
Pick PNG for text, screenshots of documents, charts, diagrams and anything you need transparent. Pick PDF to JPG for scans and photo-heavy pages, where JPG files are far smaller and look the same.
Privacy
All the work happens on your device after the page loads. There is no upload, no account and nothing stored on a server, so confidential documents stay confidential. If the PDF has a password, it is used only to read the file here and is never sent anywhere.
Limits
Browsers cap how large an image they can draw, so each page is kept under about 30 megapixels on a computer and 5 megapixels on a phone or tablet. A page that would be larger is made at a lower resolution, and the status line says so. Big PNGs also take memory: on a phone, convert long documents a section at a time. To turn PNG images back into a PDF, use PNG to PDF.
Questions people ask
Is my PDF uploaded anywhere?
No. The pages are drawn by pdf.js, Mozilla's open-source PDF reader, running inside this page on your device, and the PNG files are saved straight to your Downloads. Nothing is sent to a server.
How does the transparent background work?
Tick "Transparent background" and the page is drawn on a clear canvas instead of a white one. Anything the PDF actually paints, such as text, lines, logos and colored boxes, stays; the empty paper becomes see-through. PDFs exported from Word, PowerPoint or design apps usually have no painted background, so they come out transparent. Scanned pages are one big photo of the paper, so they stay solid.
Why are the PNG files so much bigger than JPGs?
PNG is lossless: every pixel is stored exactly, with no compression smudges around text. That makes PNG the sharper choice for text, charts and line drawings, but files are often several times larger than a JPG of the same page. For scans and photos, PDF to JPG gives much smaller files that look the same.
Which resolution should I pick?
150 DPI suits screens, slides and documents. 300 DPI is for printing or zooming into small print. A Letter page is 1275 × 1650 pixels at 150 DPI and 2550 × 3300 pixels at 300 DPI. You can also type any value from 36 to 600 DPI.
Can I convert only some pages?
Yes. Type pages and ranges in the Pages box, for example 2, 5-7 or 12- (page 12 to the end), or leave it empty for all pages. Download each image separately or all of them in one ZIP file.
Can I add a PNG of a PDF page to a slide or a website?
Yes, that is the most common use. A transparent PNG of a logo, chart or signature page sits cleanly on a colored slide background. For a website, 150 DPI or lower keeps the file size reasonable.