PNG vs JPG vs WEBP vs AVIF: which image format should you use?

Every image you ship to a browser costs bytes, and those bytes cost page speed, mobile data, and sometimes conversions. Studies on web performance repeatedly show that images account for half or more of a typical page's weight, so the format you choose is not a minor technical detail — it is one of the largest levers you have over load time. At the same time, the wrong format can wreck a logo with jagged edges, band a gradient, or simply fail to open on a viewer someone emailed it to.

The good news is that the decision has become almost mechanical once you know four things about each format: how it compresses, whether it supports transparency, whether it supports animation, and where it actually opens. This guide compares PNG, JPG, WEBP, and AVIF on exactly those axes and gives you a decision rule you can apply in seconds.

PNG (Portable Network Graphics) was created in the mid-1990s as a patent-free replacement for GIF, and it became the default for anything on the web that needs to stay sharp. PNG compresses file size without discarding any pixel data — every time you open and re-save a PNG, the image quality stays exactly where it was. That property makes it the right home for logos, icons, screenshots, illustrations, and any image that will pass through an editing tool more than once.

PNG also supports full alpha-channel transparency, meaning a pixel can be partially transparent. That is why anti-aliased logo edges look smooth over any background when the logo is a PNG, and why designers reach for it by default. The cost of all this fidelity is size: photographic content stored as PNG is typically two to five times larger than the same photo as JPEG, because lossless compression cannot make sense of the fine, noisy detail that photographs contain.

• Lossless — no quality loss on repeated saves
• Full transparency including soft, semi-transparent edges
• Ideal for logos, icons, screenshots, line art, and UI
• Too heavy for photographs

JPEG (often written JPG) has been the standard photographic format since the early 1990s and is understood by essentially every device, camera, print lab, and piece of software ever shipped. Its compression is lossy: the encoder discards color and detail information that human vision rarely notices, guided by a quality setting you control (commonly 1–100). At quality 85–90, a photograph looks visually identical to the original while often being a tenth of the size of a PNG.

The trade-offs are equally well known. JPEG has no transparency support at all — a transparent PNG opened and saved as JPEG will gain a solid background, usually white or black. Every re-save compounds compression artifacts, so the format works best as a final delivery format rather than a working format. Text and hard edges are JPEG's weakest point; they develop ringing and "mosquito noise" artifacts much faster than smooth photographic detail does.

• Lossy with an adjustable quality slider
• No transparency, no animation
• Ideal for photographs, emails, documents, and print uploads
• Avoid for logos, text-heavy images, and repeated editing

WEBP was released by Google in 2010 with one mission: make the web faster. It compresses photographs at roughly 25–35% smaller than JPEG at equivalent visual quality while also supporting transparency like PNG — a combination no single older format offers. It supports both lossy and lossless modes, plus animated variants that loop like GIF but with far better quality per byte.

That combination is why WEBP is now the sensible default for web delivery. Every current browser supports it, major CDNs transcode to it automatically, and content management systems increasingly ship it when you upload an image. Its remaining weakness is legacy: some older design programs, niche industrial software, and very old operating systems cannot open WEBP without a plugin or converter. If your audience includes people on decade-old systems, keep a JPEG or PNG fallback available.

• Both lossy and lossless modes
• Transparency and animation supported
• Typically 25–35% smaller than JPEG for the same look
• Rare legacy tools may not open it yet

AVIF (AV1 Image File Format) is the newest mainstream format, standardized in 2019 and derived from the royalty-free AV1 video codec. It pushes compression further than anything else browser-ready: AVIF files are commonly 50% smaller than JPEG at the same perceptual quality, and it handles the artifacts that plague other formats — blocking around faces, banding in gradients, smearing on flat color — remarkably well.

AVIF supports lossy and lossless modes, full transparency, wide color gamuts, and even HDR. Its costs are encoding time and compatibility tail. Producing AVIF takes noticeably more CPU than JPEG or WEBP, so real-time conversion on low-end devices can lag, and support is thinner on legacy systems than WEBP's. For modern sites with an image CDN doing the encoding, AVIF is increasingly the first choice; as a hand-transferred file you send to unknown recipients, it remains the riskiest of the four.

• Best compression available in browsers today
• Transparency, HDR, and wide color support
• Encoding is heavier — batch conversion may be slower
• Newest format, so the oldest devices may not open it

If you remember nothing else, remember this comparison. PNG is lossless with transparency — use it for graphics and editing masters. JPG is lossy without transparency — use it for photographs you are delivering to everyone. WEBP compresses better than both and supports transparency — use it as the default web image. AVIF compresses the best of all but travels to the fewest old systems — use it when performance matters and your pipeline can transcode.

A practical delivery strategy for websites combines them: serve AVIF first with a WEBP fallback, and keep PNG or JPEG for content that must open literally anywhere. When you only get to pick one format for a file someone else will open — an attachment, a document, an upload form that lists allowed types — JPEG for photos and PNG for graphics remain the safe answers.

• Graphics, logos, screenshots → PNG
• Photos for universal delivery → JPG
• Web images, product photos, thumbnails → WEBP
• Maximum performance on modern pipelines → AVIF

Converting is straightforward when the tool runs in your browser: no upload, no account, no waiting for a server queue. Open the ConvertKit image studio, drop your files in, pick the output format, and download the results — batches of files convert together and export as a ZIP. Because the work happens on your own device, private or client material never leaves your machine.

1. Open the image converter and drop in one or more files (PNG, JPG, WEBP, HEIC, AVIF, BMP, GIF, or TIFF are accepted as input).
2. Choose the target format from the output picker — the quality slider appears automatically for lossy formats.
3. Adjust quality if needed: 85–90 for photographs, 100 when the source is a logo or text-heavy graphic.
4. Press Convert, preview the results side by side with the originals, then download individually or as a batch ZIP.

The first mistake is converting from an already-compressed copy. Every lossy generation stacks on the last, so always start from your highest-quality original — the camera file, the design export, not the version you saved from a chat app. The second is choosing PNG for photographs "because it is lossless": the fidelity is real, but the byte cost is enormous, and a quality-90 JPEG will look the same on a screen at a fraction of the size.

The third mistake is ignoring transparency in the target format. JPEG cannot store it, GIF only stores it in binary form (fully on or fully off), and flattening happens silently during conversion — you discover white halos around your logo after you have already shipped it. If transparency matters, stay in PNG, WEBP, AVIF, or TIFF, and check the preview before downloading.