PNG→WebP変換ツール

What actually changes when you convert PNG to WebP

PNG is a lossless format built for flat colour: screenshots, diagrams, logos, interface mockups. WebP can do lossless too, but its real advantage is that it can also do lossy compression — and for anything photographic, that is where the size win comes from. The same photograph typically lands 25–35% smaller as a lossy WebP than as a JPEG, and the gap against a PNG is far larger.

The important detail is that the conversion is a one-way decision. WebP lossy discards information that cannot be recovered by converting back to PNG later. If the image is a screenshot with text in it, the loss shows up first on the letter edges.

Lossless or lossy: which to pick

• Text, UI screenshots, line art, logos — use WebP lossless. You typically still save 20–30% against the PNG with no visible change at all.
• Photographs and scanned images — use WebP lossy. The saving is much larger, and the artefacts are far less visible on continuous-tone content.
• Anything you will edit again — keep the PNG. Convert a copy for delivery and leave the master alone.

When to keep PNG instead

• You need a format that every tool and platform accepts without question — PNG has universal support, WebP does not.
• The image has fine monochrome detail such as a screenshot of source code or a one-pixel grid, where lossy compression is most visible.
• You are producing an asset for print or for a desktop application, where the browser support argument does not apply.