Choosing a Lossy Image Compression Format

Which lossy format is best?

There is no single best lossy image compression format for every situation, but there is a sensible default. For photos and camera snapshots shown on the web, AVIF usually produces the smallest files at a given visual quality, WebP is a strong and widely supported middle ground, and JPEG remains the safest choice when an image must open everywhere, including older software, email clients and printers.

A practical rule: use JPEG when compatibility matters most, WebP when you want smaller files with near-universal support in current browsers, and AVIF when file size matters most and you can confirm that the software receiving the image supports it.

How lossy compression works

Lossy compression makes files smaller by permanently discarding image information that viewers are less likely to notice, such as fine color detail and subtle texture. The encoder divides the image into blocks, converts them into frequency data and stores the less important parts with less precision. The result looks similar to the original at sensible settings, but the discarded data cannot be recovered.

The main formats differ in how cleverly they do this:

• JPEG: the long-established standard for photos. Supported by virtually every device, browser and editor. No transparency. Artifacts appear as blockiness and ringing around sharp edges at low quality.
• WebP: developed for the web, with both lossy and lossless modes. Lossy WebP can keep a transparent background, which JPEG cannot. Supported by all major current browsers.
• AVIF: based on the AV1 video codec. Generally more efficient than JPEG and WebP, supports transparency and higher bit depths, but encoding can be noticeably slower and support in older apps is weaker.
• HEIC/HEIF: the default photo format on many Apple devices. Efficient, but browser and Windows support is inconsistent, so it is often converted before sharing.
• JPEG XL: a newer format designed to replace JPEG, including lossless recompression of existing JPEG files. Support varies between browsers and versions, so check current support before relying on it.

Quality sliders are not comparable between formats or even between encoders. A quality value of 80 in one tool does not mean the same file size or appearance as 80 in another, so judge results by eye and by file size rather than by the number alone.

Picking a format for common tasks

Photos and webcam snapshots for a website

Export WebP or AVIF for the page and keep a JPEG fallback if your site or platform supports serving several formats. Resize to the pixel dimensions the image will actually be displayed at before compressing; a large camera frame scaled down by the browser wastes bandwidth regardless of format.

Sharing by email, chat or upload forms

Use JPEG unless you know the recipient's software handles newer formats. Many upload forms and older applications reject WebP, AVIF or HEIC files, and some messaging services recompress images anyway.

Images that need a transparent background

JPEG cannot store transparency. Choose WebP or AVIF for lossy images with transparency, such as a cut-out profile picture or an overlay for a video call background. If edges must stay perfectly crisp, consider a lossless format instead.

Screenshots, diagrams and text

Lossy compression handles flat colors and sharp text poorly, producing visible smudging around letters and lines. For screenshots of settings menus, error messages or interface elements, PNG or lossless WebP is usually the better choice.

A simple workflow

• Keep the original file from your camera or editor untouched.
• Crop and resize first, keeping the original aspect ratio unless you intend to change it.
• Export to the chosen format, starting at a moderate quality setting.
• Compare the result with the original at 100% zoom, paying attention to skin, sky gradients and edges.
• Lower or raise quality until artifacts are just invisible at normal viewing size.

Limits and related questions

What is the most popular lossy image compression format?

JPEG is still the most widely used lossy image format, mainly because of its universal compatibility. Popularity is not the same as efficiency, though: newer formats can achieve similar quality in smaller files, which is why WebP and AVIF are increasingly used on websites.

Repeated saving degrades quality

Each time a lossy file is edited and saved again, more information is discarded. This generation loss accumulates, so always edit from the original or a lossless master and export the lossy version as the final step. Converting a JPEG to WebP or AVIF does not restore lost detail; it only adds another round of compression.

Color, bit depth and HDR

Standard JPEG stores 8 bits per channel, which can cause banding in smooth gradients. AVIF and some other newer formats can store higher bit depths and HDR content, but only if the camera, editor, encoder and viewer all support it end to end.

Metadata and privacy

Photos can contain metadata such as camera model, capture time and, on phones, location. Whether a converter keeps or removes this data depends on the tool and its settings, so check the exported file before sharing it. If you use an online compressor, verify how it handles uploaded files, including whether they are processed locally in the browser or sent to a server and how long they are retained.

Support changes over time

Browser, operating system and application support for WebP, AVIF, HEIC and JPEG XL changes with software updates. Before standardizing on a newer file format, test it in the specific browsers, devices and services your audience uses.