Choosing an image format is a trade-off between quality, file size, transparency, and browser support. Get it right and your pages load fast; get it wrong and you're shipping megabytes of unnecessary bytes — or worse, visual artifacts.
The short version
- PNG — lossless, full transparency. Best for logos, screenshots, and graphics with text.
- WebP — lossy or lossless, smaller than PNG and JPEG. The safe modern default.
- AVIF — best compression of the three, but heavier to encode and needs a capable browser.
What about JPEG?
JPEG still wins for huge photographic archives, but for most web use WebP at q75–85 looks as good at roughly half the size.
How to choose, practically
For screenshots and UI elements, keep PNG or convert to lossless WebP — text must stay crisp. For photos on your site, convert to WebP or AVIF and compare file sizes at equal quality. For icons that need to scale, keep vector SVG instead of any raster format.
ForgePlug's Image Converter turns PNG, JPEG, TIFF, WEBP, and more into any of these formats with a live preview showing exact pixel dimensions and file size before you commit. The Image Compressor lets you dial in quality with an interactive slider and see the size drop in real time — all in your browser, so your images never leave your device.
Convert and compress images
Convert between formats with smart recommendations, or compress with a live quality slider — batch supported, fully client-side.
Open Image ConverterWhy PNG is enormous for photos
PNG compression is lossless and works by finding repetition — it predicts each pixel from its neighbours and compresses the differences. On a screenshot or a logo, where large areas are identical flat colour and edges are hard, that prediction is extremely accurate and the file gets very small. On a photograph, where every pixel differs slightly from the one beside it because of sensor noise and natural gradients, there is almost nothing to predict and the file stays huge.
This is the mechanism behind the two classic mistakes. A photo saved as PNG is often five to ten times larger than a visually identical JPEG or WebP. A screenshot saved as JPEG gets visible fringing around every letter, because lossy compression discards exactly the high-frequency detail that makes text look sharp — and frequently ends up larger than the PNG would have been anyway.
Transparency is not equal across formats
JPEG has no transparency at all. PNG has full 8-bit alpha, meaning 256 levels of partial transparency, which is what makes soft shadows and anti-aliased edges look clean over any background. The useful thing about WebP and AVIF is that both support alpha in lossy mode — something JPEG cannot do and PNG can only do losslessly.
That combination matters more than it sounds. A product photo with a transparent background historically had to be PNG, and therefore large. In WebP or AVIF it can be lossy-compressed and keep its alpha channel, which is often a dramatic size reduction for exactly the images e-commerce sites have the most of.
The honest cost of AVIF
AVIF genuinely compresses better, particularly on gradients and flat-ish areas where JPEG and WebP produce banding — it supports higher bit depths, which gives it more room to represent a smooth sky without visible steps. The catch is encoding time. AVIF encoding is substantially slower than JPEG or WebP, sometimes by an order of magnitude at high effort settings. For a handful of hero images that is irrelevant; for a batch of several hundred, or an upload pipeline that encodes on demand, it is the deciding factor.
Every lossy re-encode loses quality
Converting JPEG to WebP to AVIF and back degrades the image at each lossy step, even at maximum quality, because the compression runs again on already-damaged data. Always convert from the original file rather than from a copy that has already been through the process.
Shipping more than one format
You do not have to pick a single winner. The picture element lets you offer several sources and have the browser take the first one it understands, falling back automatically. In practice that means listing AVIF first, WebP second, and a JPEG or PNG last as the universal fallback — modern browsers take the small file, older ones still get an image, and no user-agent sniffing is involved.
The performance payoff
Image bytes are the largest part of most pages. Switching from PNG to WebP typically cuts image weight substantially, and AVIF can go further again. Smaller images mean faster LCP, lower data costs, and a better Core Web Vitals score — which matters for both SEO and user experience.
One thing worth doing before any of this, though: check the pixel dimensions. Serving a 4000-pixel-wide photo into a 800-pixel-wide slot wastes more bytes than any format choice will recover. Resize to the size you actually display, then pick the format — in that order.