There are three image formats that account for the vast majority of images on the web, and each one has a specific job it does well. The problem is that most people pick a format out of habit — they save everything as JPG because that's what their camera produces, or everything as PNG because that's what their design tool exports, without thinking about whether that format is actually right for the content. The result is images that are larger than they need to be, lower quality than they should be, or both.

This guide explains what each format actually does, what it's suited for, and how to make the decision quickly every time — including when the newer WebP format is worth the switch.

JPG: The Workhorse for Photographs

JPG (also written JPEG) has been the dominant format for photographic images since the mid-1990s, and for good reason — it was specifically designed to compress the kind of continuous-tone, complex color information that photographs contain. Its lossy compression algorithm discards subtle color and detail variations that human vision is least sensitive to, achieving dramatic file size reductions while keeping photographs looking sharp and natural.

Where JPG excels: photographs, product images, hero images, anything with complex color gradients, skin tones, outdoor scenes, or detailed textures. On this type of content, a well-compressed JPG at 80–85% quality is visually indistinguishable from the original at a fraction of the file size.

Where JPG falls apart: images with sharp edges, flat areas of solid color, text, logos, or line art. JPG compression creates artifacts — slight blurring and color halos — around hard edges. On a photograph those artifacts are invisible, buried in the surrounding detail. On a logo or a screenshot with crisp text, they're immediately obvious. JPG also doesn't support transparency, so if you need a background-free image, JPG isn't an option at all.

One more thing worth knowing about JPG: it degrades a little every time you re-save it. Each save applies another round of compression on top of the previous one, and artifacts accumulate. If an image is going to go through multiple rounds of editing before its final version, keep it in a lossless format until the final export. Re-saving a JPG ten times produces noticeably worse results than saving once from the original.

PNG: The Right Choice for Graphics, Screenshots, and Transparency

PNG uses lossless compression — it reduces file size without discarding any image data, and the compressed file can be perfectly reconstructed to the original. This means no artifacts, no quality degradation, no matter how complex the content or how many times you save it.

Where PNG excels: logos, icons, UI screenshots, diagrams, charts, anything with text overlaid on an image, and anything that needs a transparent background. On this type of content, PNG is the only format that does the job correctly — the crisp edges and solid colors that JPG mangles are preserved perfectly, and transparency is fully supported.

Where PNG is the wrong choice: photographs. Because PNG compression is lossless, it can't achieve the dramatic file size reductions that JPG achieves on photographic content. A photograph saved as PNG might be 5–10× larger than the same photograph saved as a high-quality JPG, with no visible quality benefit on screen. Using PNG for photos is one of the most common causes of unnecessarily bloated web pages.

The transparency trap: A common mistake is saving a photograph as PNG just because it needs a transparent background — say, a product photo with the background removed. The result is a massive file for what's essentially photographic content. The better approach: if transparency isn't actually needed on the final page (because the background color is known), export as JPG instead. Save PNG transparency for cases where it's genuinely doing something the alternative can't.

WebP: The Modern Format That Does Both Jobs Better

WebP was developed by Google and released in 2010, with the explicit goal of replacing both JPG and PNG with a single format that outperforms both. It supports lossy and lossless compression, supports transparency, and consistently produces smaller files than either JPG or PNG at equivalent visual quality.

The numbers are meaningful: WebP lossy compression typically produces files 25–35% smaller than JPG at the same visual quality. WebP lossless compression typically produces files 20–30% smaller than PNG. That's not a marginal improvement — on a page with a dozen images, switching from JPG/PNG to WebP can cut total image weight by a quarter or more.

Browser support is now essentially universal. Chrome, Firefox, Safari, Edge, and Opera all support WebP, covering well over 95% of web users. The holdouts are very old browser versions that represent a vanishingly small share of traffic for most sites. For most web use cases, WebP is simply the better choice over both JPG and PNG.

Where WebP has limitations: it's not universally supported outside browsers. Some older image editing applications, email clients, and content management systems don't handle WebP well. If your images need to work in email, be downloaded and printed, or be opened in software that might not support WebP, JPG and PNG remain the safer choice. For images that live exclusively on the web and will be viewed in browsers, WebP is the better default.

GIF: One Very Specific Use Case

GIF is worth a brief mention because it still gets used inappropriately. For static images, GIF is strictly inferior to PNG — it's limited to 256 colors, produces larger files, and has no meaningful advantages. If you have a static GIF, convert it to PNG or WebP.

For simple animations, GIF is widely supported but inefficient — animated GIFs are typically very large for what they deliver. WebP animation is more efficient, and short animations are increasingly handled by MP4 video, which achieves far better compression than GIF for motion content. GIF's main advantage today is its near-universal compatibility, which matters in older email clients or messaging apps. For web use, prefer WebP animation or MP4.

The Quick Decision Guide

In practice, the format decision comes down to a short set of questions:

  • Is it a photograph or complex photographic imagery? Use WebP (lossy) if browser-only. Use JPG if it needs to work outside browsers or be downloaded for print.
  • Does it have hard edges, text, a logo, flat color areas, or a transparent background? Use WebP (lossless) if browser-only. Use PNG if it needs broader compatibility.
  • Is it a static image currently saved as GIF? Convert to PNG or WebP. There's no reason to use GIF for static content.
  • Does it need to work in email or be downloaded and used in software? Stick with JPG or PNG. WebP support outside browsers is still inconsistent.
  • Not sure? Try WebP. The WebP Converter converts from any format in seconds, and you can compare file sizes before committing.

A Few Things to Know About Converting Between Formats

Converting JPG to PNG doesn't improve quality. If a JPG already has compression artifacts, converting it to PNG locks those artifacts in losslessly — you get a large PNG file that still looks like a compressed JPG. PNG preserves what's there; it can't restore what JPG already discarded. If you need a high-quality version of an image, go back to the original source file.

Converting PNG to JPG discards transparency. Any transparent areas in the PNG will be filled with a background color (usually white or black, depending on the tool) in the JPG output. Check what's happening to transparent areas before committing to the conversion.

Converting to WebP is generally safe and reversible. The WebP Converter handles both directions — JPG/PNG to WebP, and WebP back to JPG or PNG — so you can convert to WebP for the web-facing version of an image while keeping the JPG or PNG as your working copy.

Format choice is one of those decisions that's easy to get right once you know the rules, and the payoff — smaller files, better quality, faster pages — is immediate. If you're currently using PNG for photographs or JPG for logos, fixing that alone will make a noticeable difference.