PNG's lossless compression works well for images with flat areas of solid color and simple, repeating patterns. A basic logo on a white background compresses efficiently because there's not much variation to store. But the moment you add semi-transparency — soft drop shadows, feathered edges, anti-aliased text, gradients that fade to transparent — the alpha channel alone starts contributing significantly to file size. PNG stores the alpha channel losslessly, meaning every pixel's transparency value gets the same meticulous treatment as the color data. A product image with a soft shadow on a transparent background can easily be 2 to 4MB as a PNG, even though visually it's a fairly simple image. The subtlety of the transparency transitions is what drives the size up.
AVIF handles transparency differently. It encodes the alpha channel using the same AV1-based compression as the color data, which means transparency information gets compressed with a modern, efficient codec rather than DEFLATE. The result is that even complex, graduated transparency — the kind that makes PNG files balloon — compresses to a fraction of the size. Soft shadows, glows, and feathered cutouts that would produce a 3MB PNG can often compress to 200 to 400KB as AVIF while the transparent areas look identical on screen.
Where AVIF quality settings matter most for transparent graphics
For opaque photographs, AVIF quality settings behave predictably: higher quality means larger file, lower quality means more visible compression. For graphics with transparency, quality settings interact with the alpha channel in a way that catches people out. At lower quality settings, AVIF may introduce very slight banding or softening around hard transparent edges — the kind of crisp cutout you get from a logo exported against a transparent background. This is usually only visible on close inspection, but if you're converting a logo that will be displayed at a large size on a dark background, it's worth checking the result at quality 80 before committing. For most web use at typical display sizes, quality 75 to 85 produces clean edges. If you need pixel-perfect edges for a logo that will be scaled up, quality 85 to 90 is the safer choice. Worth noting: this converter's slider defaults to 60, below that whole range, so it's worth raising before you convert anything where edge crispness matters.
The encoding speed issue is real and worth knowing about before you drop a batch of large PNGs into the converter. AVIF encoding in the browser using WebAssembly is considerably slower than PNG or JPEG encoding — a 2MB PNG might take 5 to 15 seconds to encode as AVIF depending on your device. This isn't a bug; it's the cost of the AV1 codec's compression complexity, and this converter already uses AVIF's faster speed:8 preset rather than the slowest, most exhaustive setting to keep that time reasonable. For a handful of files it's a minor inconvenience. For large batches, the PNG to WebP converter is significantly faster if you need to process many files quickly and the modest compression difference between WebP and AVIF isn't critical to your use case.
Using AVIF for product images and when to keep PNG as a fallback
Product photography on e-commerce sites is one of the strongest cases for PNG-to-AVIF conversion. A white-background product cutout that's 1.5MB as PNG might drop to 120KB as AVIF at quality 80 with no perceptible difference at the sizes product pages display images. Multiply that across hundreds of product images and the page load difference is meaningful. The practical consideration is fallback: browsers that don't support AVIF will get a broken image if you serve only AVIF. The standard approach on the web is to use an HTML picture element with an AVIF source and a PNG or JPEG fallback, so every browser gets an image it can render. If you're uploading to a platform rather than managing your own HTML, check whether the platform serves AVIF to supported browsers and falls back automatically, or whether it just serves whatever you upload. For platforms that handle format negotiation themselves, the JPG to AVIF converter covers the non-transparent product photo case where JPEG is your current format.