From lossless PNG to lossy WebP
PNG keeps every pixel exactly, which is ideal for editing but expensive in bytes. The WebP files Convertisio creates use lossy, quality-controlled compression: the encoder discards the detail that is least likely to be noticed and stores the rest far more compactly. The result is usually much smaller than the PNG, though no longer a pixel-for-pixel copy of it.
How much you save depends on the picture:
- Photos saved as PNG tend to shrink the most. PNG is a heavy way to store a photograph, usually several times larger than a JPG of the same image, and WebP is more compact still.
- Graphics, illustrations and screenshots can also shrink substantially, although PNG already handles large areas of flat colour fairly well, so the gap is often less dramatic.
Transparency comes along intact. WebP supports a full alpha channel, so logos, icons and cut-out product shots keep their transparent backgrounds and soft edges, which a JPG could not offer. If your photos are JPGs rather than PNGs, the JPG to WebP converter is the better starting point.
PNG vs WebP
| Aspect | PNG | WebP |
|---|---|---|
| Compression | Lossless | Lossy or lossless (Convertisio creates lossy WebP) |
| Transparency | Yes | Yes |
| Animation | APNG variant | Animated WebP |
| Typical file size | Large, very large for photos | Usually much smaller |
| Re-saving | No loss, however often you save | Each lossy save loses a little |
| Where it opens | Practically everywhere | All current major browsers; some older software does not accept it |
| Best for | Master copies, editing, exact pixels | Publishing on websites and in apps |
When to keep your PNG
WebP is a delivery format. It is excellent for the version of an image that visitors download, but less suited to being your only copy:
- Keep the PNG as your master. If you will edit the image again, work from the lossless original and export a fresh WebP afterwards, rather than editing and re-saving the WebP.
- Pixel-exact work. Pixel art, interface mock-ups and screenshots for documentation can show softened edges at lower quality settings. Use a high quality value, or keep them as PNG.
- Destinations that reject WebP. Some print services, email clients and older office software still do not accept it. If transparency is not needed there, PNG to JPG gives broad compatibility with a smaller file.
One more honest note: this converter produces lossy WebP only. If you specifically need lossless WebP output, it is not the right tool for that job.
Where the switch pays off
Images are often the heaviest part of a web page, so replacing large PNGs is one of the simplest ways to make a site feel quicker. The biggest wins usually come from:
- Screenshots in articles and documentation, which are frequently saved as full-size PNGs straight from the operating system;
- Product images with transparent backgrounds, where JPG is not an option but PNG is unnecessarily heavy;
- Illustrations and banners exported from design tools that default to PNG.
Before you switch, check that your content management system, theme or app accepts WebP uploads. Many current platforms do, but some older ones, along with some email clients, still expect PNG or JPG.
Getting the best WebP from a PNG
Quality
The default of 85 suits most web images. For screenshots and graphics with small text, try 90 or higher to keep edges crisp; for large photographs, values between 75 and 85 usually look clean while saving more space. Check one result at full size before converting a whole batch.
Dimensions
Resizing often saves more than lowering quality. A PNG exported 4,000 pixels wide but shown at 1,200 on your site wastes most of its bytes. Use Settings → Size to fit images within the largest width or height your layout displays; the aspect ratio is preserved and nothing is enlarged.
Animation, metadata and colour
Animated PNGs (APNG) are converted as a still image from their first frame, with a warning. EXIF metadata is not copied. Colours are converted to sRGB, the standard colour space of the web, so wide-gamut artwork may look slightly less saturated.
Safari
Some Safari versions cannot create WebP files natively. In that case Convertisio downloads a built-in WebP encoder of about 300 KB as soon as you choose WebP as the output, and the conversion still runs entirely on your device.