How to Convert PNG to WebP Online (Free, No Signup)

WebP has become the default choice for web images because it typically shrinks file size by 25-35% compared to PNG at a visually similar quality, which means faster page loads and better Core Web Vitals scores. If you've got a folder of PNG screenshots, product photos, or icons that need converting, here are the three practical routes, with the trade-offs of each spelled out.

Why Bother Converting PNG to WebP

PNG is a lossless format, which makes it great for screenshots, logos, and images with transparency, but the files are often larger than they need to be. WebP supports both lossless and lossy compression, plus transparency (alpha channel), so it can replace PNG in almost every use case while cutting file size noticeably. Google's own PageSpeed Insights will flag large PNGs and recommend WebP (or AVIF) as a fix, so if you're optimising a website, this conversion is usually one of the first wins available.

The main downside: WebP support in older software (some CMS plugins, older image viewers, certain email clients) can be patchy, so keep a PNG fallback if you're serving images to a very mixed audience. Browser support itself is not an issue any more - Chrome, Firefox, Edge, and Safari (from version 14) all render WebP natively.

Method 1: Convert Online (Fastest for One-Off Jobs)

For a handful of images, or when you don't want to install anything, a browser-based converter is the quickest option. The general steps are the same across most tools:

1. Open the converter in your browser.
2. Drag and drop your PNG file(s), or click to browse and select them.
3. Choose WebP as the output format, and set a quality level if the tool offers one (80-85 is a sensible default for photos; use lossless or 95+ for graphics with sharp edges or text).
4. Convert and download the result, either individually or as a zip if you've batched several files.

Konomic's file conversion tool at / works this way - upload your PNGs, pick WebP as the target format, and download the converted files without creating an account. Because Konomic runs on servers based in Germany and deletes uploaded files automatically within an hour, it's a reasonable option if you're converting anything you'd rather not leave sitting on a US-based server indefinitely. It's one of several solid choices though - iLovePDF and Smallpdf both offer similar image conversion features bundled alongside their PDF tools, and Sejda has a straightforward converter with a daily task limit on the free tier. If you're doing this occasionally, any of them will do the job; the differences show up in file size limits, batch handling, and where your data is processed.

Method 2: Command Line with cwebp (Best for Batches and Automation)

If you're converting dozens or hundreds of images, or you want this baked into a build pipeline, Google's own cwebp tool (part of libwebp) is the standard approach.

Install it via your package manager:

• macOS: brew install webp
• Ubuntu/Debian: sudo apt install webp
• Windows: download the precompiled binaries from Google's WebP project page

Convert a single file:

cwebp -q 80 input.png -o output.webp

Batch-convert an entire folder (macOS/Linux):

for file in *.png; do cwebp -q 80 "$file" -o "${file%.png}.webp"; done

The -q flag sets quality from 0-100; drop to -lossless if you need pixel-perfect output (useful for icons, logos, or diagrams with flat colour and text). This method gives you full control over compression and is genuinely faster than uploading files anywhere, since nothing leaves your machine.

Method 3: Image Editors (GIMP, Photoshop, Affinity Photo)

If you're already editing the image, exporting straight to WebP saves a step.

GIMP (free): File > Export As, type a filename ending in .webp, click Export, then adjust the quality slider and toggle lossless/lossy in the dialog that appears.

Photoshop (2020 and later): File > Export > Export As, choose WebP from the format dropdown, and set quality. Older Photoshop versions need a plugin, since native WebP support was only added a few years ago.

Affinity Photo: File > Export, select WebP, and adjust the quality slider in the export dialog.

This route makes sense when you're already doing colour correction, cropping, or resizing and want to finish with the right output format in one pass.

Choosing the Right Quality Setting

A few practical guidelines that save trial and error:

• Photographs: quality 75-85 is usually indistinguishable from the original at normal viewing sizes, and gives the biggest file size reduction.
• Screenshots and UI graphics with text: go higher, 90-100, or use lossless mode - text edges degrade noticeably at lower quality settings.
• Icons and logos with flat colours: lossless WebP often still beats PNG in file size while keeping perfect edges.
• Images with transparency: WebP handles alpha channels in both lossy and lossless modes, so transparent PNGs convert cleanly either way - just check the output at 100% zoom if the image has fine transparent detail.

If you're unsure, convert one test image at a couple of settings and compare file size against visual quality before batch-processing the rest.

Privacy: Where Do Your Images Actually Go?

This is easy to overlook, but worth a moment's thought if the images contain anything sensitive - internal documents, ID scans, unreleased product photos, or personal photos. When you upload to an online converter, the file typically lands on the provider's servers, gets processed, and should then be deleted. The details vary a lot between services: some state a retention window, some don't specify one clearly, and jurisdiction affects what legal protections apply to that data in the meantime.

If that matters for your files, look for tools that are explicit about deletion timing and are based in a jurisdiction with strong data protection law - EU-based processing under GDPR gives you clearer rights than services hosted elsewhere with vaguer policies. For genuinely sensitive material, the command-line or desktop editor routes above avoid the question entirely, since nothing leaves your computer.

Wrapping Up

For occasional conversions, an online tool is the path of least resistance - Konomic, iLovePDF, Smallpdf, and Sejda all handle PNG to WebP conversion competently, so pick whichever fits your file size limits and comfort with where the data is processed. For bulk jobs or repeatable workflows, cwebp on the command line is faster and keeps files local. Either way, WebP is worth the switch for most web use cases - the file size savings add up quickly across a whole site or image library.