How to Convert PNG to WebP (and Cut Your Image Files in Half)

If you publish images on the web, PNG → WebP is the single biggest "free" file-size win available. WebP is ~50% smaller than PNG for graphics and screenshots, ~25% smaller than JPEG for photographs, and is supported by every modern browser. Server-side bandwidth goes down, Largest Contentful Paint goes down, your Core Web Vitals score goes up.

This guide covers the conversion, the lossy/lossless choice, and when PNG is still the right format.

Why WebP wins on size

PNG uses zlib-style deflate compression, which works well for uniform regions but poorly for noisy / photographic content. WebP uses two different modes:

• Lossless WebP — backward-reference prediction + arithmetic coding. For PNG-style content (screenshots, logos, illustrations), output is typically 50-80% smaller than PNG with zero quality loss — pixel-perfect identical to the source.
• Lossy WebP — VP8 video-style block prediction. For photographic content, output is 2-5× smaller than PNG with visually identical quality, though technically not pixel-perfect.

The "convert" tool picks the right mode automatically based on the image: photos go lossy, graphics go lossless.

Convert with Dropvert

Convert PNG to WebP. Drop the file (or many — bulk is supported), click convert, download. Encoded entirely in your browser via @jsquash WebP WASM — no upload, no account, no file-size limit.

If you want explicit control over the lossy quality slider, use Compress Image with WebP picked as output format. The default quality (80) is visually indistinguishable from the source for most photographs.

When to keep PNG instead

A few specific cases:

• You need the alpha channel preserved bit-perfectly and the consumer is older software (legacy CMS, old Photoshop versions, ancient mail clients). WebP's alpha works in modern software but isn't universal.
• You're sending the file to be printed. Print pipelines often only accept PNG, JPEG, or TIFF.
• The image will be opened by a non-web user — designers, partners on old computers, etc. PNG is universally readable; WebP support outside browsers is improving but uneven.
• The file is going into a Word document or email signature. Office's WebP support is recent (since 2021). If the recipient might have an older version, PNG is safer.

For everything that lives on a website or in modern apps, WebP is the right choice.

When AVIF is better than WebP

AVIF compresses about 20% tighter than WebP and supports all the same features. The trade-off: AVIF encoders are slower (5-10× WebP), and Safari support arrived later. For raw bandwidth savings, AVIF wins; for "ship it and don't worry", WebP is the safe default.

Convert PNG to AVIF if you want to try it. The output file will be smaller; the encode takes ~5× longer than the WebP path.

Reverse direction

If you receive a WebP and need PNG (e.g. for printing or for an older tool): Convert WebP to PNG. The conversion is lossless on either direction when WebP is in its lossless mode; converting back from lossy WebP recovers a PNG, but the data the WebP encoder discarded stays discarded.

FAQ

Will WebP work in email? Modern clients render it (Gmail, Apple Mail, Outlook 2021+). Older Outlook versions render a broken-image placeholder. For marketing emails to a broad audience, JPEG remains safer.

Can I keep the transparency? Yes — WebP supports full alpha in both lossy and lossless modes. Drop your transparent PNG and the output WebP keeps the alpha intact.

Does the conversion run on my computer or yours? Yours. The WebP encoder runs as a WebAssembly module in your browser. The file never leaves your device. This is also why there's no file-size limit — your machine's resources are the only constraint.