Choosing the wrong image format costs real performance: unnecessary bandwidth, slower page loads, and lower PageSpeed Insights scores. For years, the choice was simple — JPG for photos, PNG for anything needing transparency. Then WebP arrived and reduced file sizes by 25–34% at equivalent quality. Now AVIF promises reductions of 50% versus JPG with better quality at low bit rates. Converting your existing image library to the right format is one of the most impactful, zero-code web performance optimizations available.
The Four Main Web Image Formats Compared
JPG (JPEG) is the web's oldest photo format. It uses lossy compression designed specifically for photographic content — the algorithm exploits the fact that human eyes are less sensitive to color detail than to luminance. JPG produces small files for photographs but struggles with sharp edges, text, and solid-color areas, where compression artifacts become visible. JPG does not support transparency.
PNG (Portable Network Graphics) was created to replace GIF with lossless compression and full transparency support. PNG preserves every pixel exactly, making it ideal for logos, screenshots, and graphics with sharp edges. The trade-off is file size: a PNG screenshot is typically 3–5 times larger than an equivalent JPG. PNG has no lossy compression mode, so you cannot trade quality for smaller file sizes as you can with JPG.
WebP was released by Google in 2010 and is now supported by all modern browsers. It achieves 25–34% smaller files than JPG for photographs and up to 26% smaller than PNG for lossless graphics, while supporting both transparent and animated images. AVIF is newer still — derived from the AV1 video codec — achieving up to 50% better compression than JPG while maintaining superior quality, particularly at low bit rates. Browser support for AVIF reached approximately 95% by 2025.
When to Convert JPG to WebP
Converting existing JPG photographs to WebP is the single highest-impact image optimization for most websites. If your site hosts product photos, blog article images, or any photographic content, converting to WebP reduces file sizes by roughly 30% without any perceptible quality change at equivalent quality settings. For a site with 100 product images averaging 200 KB each, the conversion saves approximately 6 MB per page load — a dramatic reduction in bandwidth.
WebP supports both lossy and lossless compression. For photographs, use lossy WebP at quality 80–85 — this produces visually identical results to JPG at 80–85 while being smaller. For graphics, icons, and screenshots originally in PNG format, use lossless WebP — it will be smaller than the PNG while maintaining pixel-perfect quality.
The one remaining limitation of WebP is that it cannot be opened by older image editing applications. If you need to deliver files that clients or partners will edit in Photoshop or Illustrator, keep JPG or PNG as the source format and convert to WebP only for web delivery. Never discard your original source files after converting — recompressing from WebP introduces generation loss.
PNG vs. WebP for Logos and Screenshots
For logos, icons, and UI screenshots, the choice between PNG and WebP depends on your priorities. If your workflow involves editing the files regularly, PNG remains the better source format because of its universal editor support. For web delivery, lossless WebP is smaller and functionally equivalent. A PNG logo of 150 KB becomes approximately 80–100 KB in lossless WebP — a 30–50% reduction with zero quality loss.
Both PNG and lossless WebP support full alpha-channel transparency, so either can place a logo on any background color without a white box artifact. The advantage of lossless WebP becomes more pronounced with larger images — a 2 MB PNG screenshot can become 1.2–1.4 MB in lossless WebP.
SVG is often the best format for logos and icons that need to scale to any size without quality loss. Unlike PNG and WebP (both raster formats), SVG is vector-based — it scales perfectly from a 16×16 favicon to a 2000-pixel wide hero banner. If your logo was created in a vector tool like Figma or Illustrator, export as SVG for web use. Convert to raster formats only when the SVG is not appropriate, such as complex detailed illustrations or when a raster thumbnail is specifically required.
AVIF: The Next-Generation Format
AVIF (AV1 Image File Format) achieves significantly better compression than WebP — typically 30–50% smaller file sizes at equivalent quality — with particularly strong performance at low quality settings. A JPG at quality 60 that shows significant artifacts can be matched by AVIF at quality 60 with far less visible compression degradation.
The practical catch with AVIF is encoding speed. Encoding a single AVIF image takes considerably longer than encoding WebP or JPG — seconds to minutes for high-resolution images versus milliseconds for JPG. For large image libraries, AVIF encoding can be prohibitively slow for on-the-fly conversion. Offline batch conversion at build time, or using a CDN with AVIF transcoding, are the practical delivery methods.
The recommended approach in 2025 is to use a picture element with AVIF as the preferred source and WebP as the fallback. This serves AVIF to browsers that support it (the majority), WebP to the next tier, and JPG to legacy browsers. An image converter that exports multiple formats simultaneously makes building this multi-source pipeline straightforward.
Image format conversion is a one-time optimization with permanent performance benefits. Converting your existing JPG and PNG image library to WebP — or AVIF for the best compression — reduces page weight by 25–50% with no perceptible quality change. The practical priority: convert photographs from JPG to WebP first (highest volume, biggest savings), then convert PNG graphics to lossless WebP. Evaluate AVIF for new images if your encoding pipeline supports it. An image format converter lets you make these conversions directly in the browser without installing software — compare output formats and quality settings before committing to a workflow.