Image format checker

What the image format checker does

This tool scans a webpage, finds its images, and reports the file format of each one. It helps you see which image types a page uses and whether they align with modern performance practices.

Image formats differ in compression, transparency support, and browser compatibility. JPEG is common for photographs, PNG for graphics with transparency, GIF for simple animation, SVG for vector graphics, and WebP or AVIF for modern, efficiently compressed images.

Why image formats matter

Images often make up the largest share of a page's transfer size. Choosing an appropriate format can significantly reduce bytes without visible quality loss. A large photographic image saved as PNG, for example, is usually much heavier than the same image saved as JPEG or WebP.

Modern formats like WebP and AVIF offer better compression than older formats for many use cases. However, adoption should consider browser support and fallback strategies. The format list helps you spot opportunities to modernize and to find images that are likely oversized.

How to interpret the result

Review the reported formats against the role of each image. Photographs in JPEG or WebP are usually appropriate. Simple icons and logos may be fine as SVG or small PNGs. Large PNG photographs and uncompressed formats are candidates for conversion.

Format alone does not determine performance. Dimensions, compression settings, and responsive delivery matter just as much. An image in a modern format can still be heavy if it is served at a much larger size than needed. Use the format report together with size and loading checks.

Common image format issues

• Photographs saved as PNG. Usually much larger than necessary.
• Animated GIFs. Often large and limited in color; video or modern formats may be better.
• Missing modern formats. No WebP or AVIF where it would reduce size.
• Inconsistent formats. Similar images stored in different formats without a clear reason.
• Oversized images. Correct format but dimensions far larger than displayed.

Practical workflow

Review the formats on image-heavy templates. Identify large images in inefficient formats and convert them, keeping quality in check. Ensure the page serves appropriately sized images for the display context. Re-check after content updates, since editors may upload images in the wrong format.

Limitations

The checker reports formats based on image URLs and attributes in the HTML response. It does not measure actual file sizes or visual quality, and it may not detect images loaded dynamically.