JPEG vs PNG vs WebP: Which Format Should You Use?

The Three Pillars of Web Images

Every image you see on the web is encoded in a specific format, and each format was designed to solve a different problem. JPEG, PNG, and WebP are the three formats that power the vast majority of images online today. Choosing the right one for each situation can dramatically reduce your page load times and bandwidth costs while maintaining visual quality.

JPEG: The Everyday Champion

JPEG (Joint Photographic Experts Group) has been the default format for photographs and complex images since 1992. It uses lossy compression, which means it permanently discards some image data to achieve smaller file sizes. For photographs, this trade-off is excellent — the human eye barely notices the difference between a high-quality JPEG and an uncompressed original, even though the file might be 90% smaller.

JPEG excels at photographs, gradients, and images with millions of colors. It does not support transparency, which means any transparent areas become solid (usually white or black). It also struggles with sharp edges, text, and flat-color graphics — these tend to develop visible artifacts called "ringing" around hard boundaries.

A high-quality JPEG at 80-85% quality is the sweet spot for most photographs. Below 60%, artifacts become noticeable. Above 90%, the quality improvement is negligible but file sizes increase significantly. For more on the encoder mechanics, see how MozJPEG differs from standard JPEG.

PNG: Pixel-Perfect Precision

PNG (Portable Network Graphics) was created in the mid-1990s as a patent-free replacement for GIF. It uses lossless compression, which means every single pixel is preserved exactly as it was in the original. This makes PNG ideal for screenshots, logos, icons, text overlays, and any image where precise edges matter.

PNG supports full alpha transparency, which means you can have partially transparent pixels — essential for logos and UI elements that need to sit on top of different backgrounds. PNG files also support a wider color depth, including 8-bit indexed color (similar to GIF) and full 24-bit or 32-bit color with transparency.

The downside is file size. A photograph saved as PNG will be three to ten times larger than the same image saved as a high-quality JPEG. This is the cost of lossless compression on complex imagery. For simple graphics with large areas of flat color, PNG actually compresses very efficiently.

WebP: The Modern Contender

WebP was developed by Google and released in 2010. It supports both lossy and lossless compression, plus transparency and even animation. In lossy mode, WebP typically achieves 25-34% smaller files than JPEG at the same visual quality. In lossless mode, it beats PNG by about 26%.

Browser support for WebP is now universal — all major browsers have supported it since 2020. The remaining concern is ecosystem support: some email clients, older image editors, and certain content management systems may not handle WebP natively. For email specifically, see the email image guide. But for the web specifically, WebP is a strong default choice.

WebP does have a maximum resolution of 16,383 x 16,383 pixels, which is rarely a practical limitation. It also does not support progressive loading the way JPEG does, though this matters less with modern connection speeds.

When to Use Each Format

Use JPEG for photographs and complex images where file size matters more than pixel-perfect accuracy. Use PNG for screenshots, logos, icons, and any image with text or sharp edges that need to remain crisp. Use WebP when you need the smallest possible file size and your delivery platform supports it — which for the web is essentially everywhere.

For a compression tool like TinImg, the best approach is to try multiple formats and compare the results. A photograph might compress best as WebP, while a screenshot with text might actually be smaller as a well-optimized PNG than as a lossy WebP.

A Worked Example: One Photo, Three Formats

Take a typical 4032×3024 iPhone photograph — a holiday picture with sky, faces, and foliage. The original HEIC straight off the camera might be around 3.2 MB. Here is what happens when you save the same pixels in each web-friendly format at quality 80:

• Standard JPEG (libjpeg, q=80): roughly 480 KB. Good baseline, broadly compatible.
• MozJPEG (q=80): roughly 430 KB. Visually identical to the libjpeg version, ~10% smaller, and decodes in any standard JPEG viewer.
• WebP lossy (q=80): roughly 340 KB. About 30% smaller than standard JPEG. Universal browser support but a few mail clients and older editors still don't read it.
• PNG (lossless): roughly 4.8 MB. About ten times the size of the JPEG. PNG was never the right choice for a photograph.

The takeaway: for photographs, lossy compression is mandatory, and the choice between MozJPEG and WebP is mostly about delivery context. For the public web, WebP usually wins. For email or "save and send a single file to a colleague," MozJPEG is the safer bet.

Common Misunderstandings

• WebP is not always smaller than JPEG. For photographs, yes. For images that already compress poorly (heavy noise, film grain), WebP and JPEG land within a few percent of each other.
• PNG is not the right choice for photos. PNG is lossless, which means a photograph saved as PNG keeps every micro-variation of every leaf and every JPEG artifact in the source. The result is a giant file with no visible benefit. Use PNG for screenshots, logos, and graphics with flat color.
• A higher quality number does not always mean a better-looking image. Above quality 90, JPEG files grow rapidly while looking identical to the human eye. The encoder is preserving frequencies you cannot see.

Frequently Asked Questions

Q: Should I always convert my JPEGs to WebP?

For images served on a website, yes — use the `<picture>` element with a WebP source and a JPEG fallback. The browser picks the best supported format automatically, and you save 25–30% on bandwidth. For images stored locally or sent via email, JPEG remains the safer choice because the recipient may use a tool that doesn't handle WebP.

Q: Is there a reason to use lossless WebP instead of PNG?

Lossless WebP is typically about 25% smaller than equivalent PNG with no visual difference. If your delivery target is the web, lossless WebP wins on size. If your target includes desktop image editors or older mail clients, PNG is still the universal default.

Q: How do I pick the right quality setting?

For most photographs, quality 75–85 in MozJPEG or WebP gives the best balance: visually indistinguishable from the original at small enough file sizes that they load fast on mobile networks. See how image compression works for the full explanation of why this range is the sweet spot.