JPEG, WebP, or PNG for a strict size limit

Output format matters as much as the quality setting. A photograph, a transparent logo, and a scanned signature have different visual structures. The format that works well for one can waste bytes or damage detail in another.

The first rule is practical: use a format accepted by the destination. A smaller WebP result is not useful if the upload form only accepts JPEG or PNG.

Quick decision guide

JPEG is the safe default for photos

JPEG uses lossy compression and is designed for continuous-tone images such as photographs. It is supported across browsers, editors, document systems, and old upload portals. When a form gives no format guidance, JPEG is usually the most compatible option.

JPEG does not support transparency. When a transparent PNG is converted to JPEG on this site, transparent pixels are filled with white. If the original contains a logo meant for a dark background, inspect the result carefully.

At very low file sizes, JPEG can produce block boundaries, ringing around sharp edges, and smeared fine text. A small reduction in dimensions can look better than forcing the quality to the bottom of the range.

WebP often keeps more quality per byte

WebP supports lossy and lossless compression, plus transparency. For many photographs, a lossy WebP can be smaller than JPEG at a similar visual quality. It is a strong option for websites, modern content systems, and any destination that explicitly lists WebP.

Compatibility with browsers is broad, but upload forms, older desktop software, and government systems may still reject it. Check the destination before you choose it.

The MDN image format guide describes WebP as supporting transparency and providing better compression than older PNG or JPEG in many web uses.

PNG protects exact pixels, not tiny file budgets

PNG is lossless. It is excellent for flat-color graphics, screenshots with sharp text, signatures, line art, and images that need a clean alpha channel. It is less efficient for detailed photographs because it tries to preserve every pixel exactly.

A PNG encoder does not expose the same useful quality range as JPEG or WebP. To fit a detailed PNG under a strict target, the compressor may have to reduce width and height. For a photo, converting to JPEG or WebP can preserve more useful resolution within the same number of bytes.

What about AVIF and HEIC?

Modern browsers can decode many AVIF files, so the site accepts AVIF input where the browser supports it. Canvas export support is less consistent, so the download choices remain JPEG, WebP, and PNG.

HEIC and HEIF are common on Apple devices. ImageCompressor.pics converts them locally before running the same compression pipeline. The first conversion can take longer because the browser loads a local decoder module. No image is sent to a conversion server.

Choose by destination, then by content

1. Read the upload form and note its accepted extensions.
2. If only JPEG is accepted, choose JPEG.
3. If WebP is accepted and the image is a photo, test WebP for better quality per byte.
4. If transparency or sharp line art matters, keep PNG or use WebP with transparency.
5. If the target is extremely small, crop and resize before lowering quality further.

Inspect the downloaded result

A successful byte count does not guarantee that the image is useful. Zoom in on faces, small text, stamps, hair, thin signature strokes, and color edges. If those details break down, reduce dimensions less aggressively by choosing a larger target, or crop unused space so more of the byte budget goes to the subject.