Image to WebP Converter: Resize and Compare File Size
Convert a JPEG, PNG or WebP image to WebP in your browser, with quality, maximum dimensions and a before/after size comparison.
Your inputs
Static images only. Limit: 20 MiB and 16 megapixels. Conversion stays in your browser.
Your result
Enter your values, then choose Calculate.
Check the preview and actual file size before using the converted image.
Calculation breakdown
Method, assumptions and worked example
How it works
The browser decodes the image, fits it within both maximum dimensions while preserving aspect ratio, and encodes the canvas as WebP at your chosen quality. Smaller images are not enlarged. The page checks the returned MIME type so a browser PNG fallback is never mislabeled as WebP.
Worked example
A 4,000 × 3,000 image fitted inside 1,920 × 1,920 becomes 1,920 × 1,440. File size depends on the image and encoder; conversion can sometimes make a file larger. The example button creates a small local demonstration image.
Using the result
Use static JPEG, PNG or WebP files up to 20 MiB and 16 million decoded pixels. Animation and original metadata are not preserved; a decoded frame is converted. Transparency is retained where supported. Browser color handling and compression can change appearance, so inspect the output before publishing. No selected image is submitted to a conversion server.
Frequently asked questions
Is conversion always smaller?
No. The result compares actual bytes and reports an increase when applicable.
Can this preserve GIF or animated WebP?
GIF is not accepted. Animated WebP is not preserved as animation; use this tool for static images.
Method review and references
Formula and content reviewed on 10 October 2026. Worked examples are hypothetical. Methods and assumptions are explained on each page. Health estimates are not clinical measurements; symbolic tools are for entertainment.