WebP vs PNG: Which Format Should You Use?

WebP is the format every web developer whispers about, and PNG is the format everyone already trusts. Both support transparency, both are lossless-capable, and both get used for completely different reasons. Here's how to pick, and how to convert between them when you need both.

What is WebP?

WebP is Google's image format, designed specifically for the web. It combines:

Excellent compression, typically 25–35% smaller than JPEG and PNG at the same visual quality
Lossy and lossless modes in a single format
Transparency (like PNG)
Animation (like GIF, but far smaller)

Every major browser has supported WebP since around 2020, so it's safe to use for website images today.

What is PNG?

PNG is a lossless raster format that has been a web staple since the 1990s. It's the default choice for screenshots, graphics with text, and anything requiring pixel-perfect transparency. Its weakness is file size: PNG files are large compared to modern formats.

WebP vs PNG: side by side

	WebP	PNG
File size	Much smaller	Larger
Lossless mode	Yes	Yes
Transparency	Yes	Yes
Animation	Yes	No
Photo quality at same size	Better	Good
Browser support	All modern browsers	Universal
Tool support	Good, improving	Universal
Best for	Web images, photos, animations	Screenshots, UI graphics, printing

When to use WebP

Choose WebP for anything that lives on the web:

Website photos and product images
Blog post illustrations
Animated images (replace GIFs)
Images where every kilobyte counts (page speed, Core Web Vitals)

When to use PNG

Choose PNG when compatibility or precision matters more than size:

Screenshots with sharp text
UI mockups and design deliverables
Images going into documents or presentations
Files that will be edited later (lossless round-trips)
Older software, email clients, or printing workflows that don't understand WebP

How to convert between them

The Image Converter on SlimImg converts between JPG, PNG, and WebP in your browser, no uploads, no accounts.

Open the converter
Drop in your images (batch is supported)
Choose WebP or PNG as the output
Download the converted files

Converting WebP to PNG is lossless in both directions, the pixels are preserved, only the container changes. Converting PNG to WebP lossy is where the size savings come from.

Choosing the right conversion settings

PNG → WebP lossy: quality 75–80 looks identical to the PNG for photos and cuts size dramatically
PNG → WebP lossless: use for graphics with text or sharp edges, smaller than PNG, still lossless
WebP → PNG: always lossless; no settings needed

If you're not sure which direction makes sense, read the PNG to JPG and WebP to JPG guides too.

A real comparison: the same image, both formats

"25–35% smaller" is abstract until you see it on one image. Here's a typical website hero photo and a UI graphic, sized in both formats:

Image	PNG	WebP lossless	WebP lossy (q78)
Photo (hero, 1600 px)	4.2 MB	3.1 MB	520 KB
UI graphic with text	190 KB	140 KB	, (lossy mangles text)

Two lessons from the table. First, for photos, the lossy WebP is the real winner, 8× smaller than PNG with an invisible difference. Second, for graphics with text, you use lossless WebP (still ~25% smaller than PNG), the lossy column is intentionally blank because it would ruin the glyphs.

The one question that decides it

Every WebP-vs-PNG decision collapses to one question: who will consume the file?

If it's a web browser → WebP. Every modern browser supports it, and the size savings directly improve load time and Core Web Vitals.
If it's a person, a document, or a legacy tool → PNG. Email clients, print workflows, presentation software, and older operating systems all handle PNG without a thought.
If it's your own future editing → PNG (or WebP-lossless). Both round-trip without degradation; PNG wins on universal tool support.

When in doubt, keep a PNG master and serve WebP copies on the web, you get the size win where it matters and the compatibility where it counts.

Decision table for common tasks

Task	Format	Why
Website hero image	WebP lossy q75–80	Smallest file, invisible loss
Blog screenshot with code	WebP lossless	Sharper than PNG, 25% smaller
Image for a client email	PNG	Compatibility
Print-ready export	PNG (or TIFF/PDF)	WebP isn't a print format
Animated sticker/GIF replacement	WebP (animation)	Animates at a fraction of the size
App icon for app store	PNG	Store pipelines expect PNG

Converting between them the right way

The Image Converter handles the direction you need:

PNG → WebP lossy (photos): quality 75–80, looks identical, dramatically smaller
PNG → WebP lossless (graphics): smaller than PNG, still lossless
WebP → PNG: always lossless, no settings to worry about

One warning: converting lossless PNG to lossy WebP is a one-way door. Keep the PNG master if you might need the original detail later. And when you're deciding between more than two formats, the image formats guide compares the whole field.

A 60-second test for your own files

Not sure which side your image falls on? Run the practical test:

Convert a copy to WebP lossy at quality 78
Open the original PNG and the WebP side by side at 100%
Look at text edges, gradients, and fine detail
If you can't tell them apart, WebP is safe for the web. If text or edges look soft, use WebP lossless or keep PNG

This takes under a minute and gives you a decision based on your actual image, not a general rule, the general rule (photos → lossy WebP, graphics → lossless/PNG) is only a starting point.

WebP vs PNG questions

Does WebP support transparency?

Yes. WebP supports full alpha transparency, exactly like PNG, in both lossy and lossless modes.

Is WebP smaller than PNG?

Almost always. For the same image, WebP lossless is typically 20–50% smaller than PNG, and WebP lossy is dramatically smaller.

Can I use WebP for print?

No, print workflows expect PNG, TIFF, or PDF. Convert WebP to PNG first using the Image Converter.

Should I replace all my PNGs with WebP?

On websites, yes, if the platform supports it. For files you share with other people, PNG is still the safer default. When in doubt, keep a PNG master and serve WebP copies on the web.

Does converting between WebP and PNG lose quality?

No, both formats support lossless conversion between each other. The pixels survive the round trip; only the container changes.

For a full comparison of every common format, see the image formats guide.

A default that rarely needs revisiting

Serve WebP on the web and keep PNG for anything you hand to other people. When in doubt, keep a PNG master and let the platform convert to WebP, so you get the size win where it matters and the compatibility where it counts.