Guide
JPG, PNG or WebP: Which Format?
Start with the receiving application's requirements, then consider transparency and compression. A different extension does not create more image detail.
Reviewed October 12, 2026
Use JPG for a photo when JPEG is accepted and a small file matters. Use PNG when you need transparent pixels or a lossless export of a graphic. Use WebP when the destination accepts it and you want a format that supports transparency and efficient compression. No format is always the smallest for every image.
Image format comparison
| Format | Transparency | Compression | A practical choice for |
|---|---|---|---|
| JPG / JPEG | No alpha channel | Usually lossy | Photos and services that require JPEG |
| PNG | Yes | Lossless | Transparent graphics, screenshots, and precise edges |
| WebP | Yes | Lossy or lossless | Web images where the receiving system supports WebP |
This table describes format capabilities. ToolFoundry exports lossy JPG and WebP, or lossless PNG, from a decoded still image. Its converters do not preserve animation, source metadata, or every color-management property.
Example: a transparent logo
A 600 x 600 WebP logo with transparent corners stays 600 x 600 in either output. WebP to PNG keeps those corners transparent. WebP to JPG fills them with white. This affects how the logo looks on a colored background, even though its pixel size is unchanged.
Example: a photo for an upload form
If a form requires JPEG, 1200 x 900 pixels, and less than 200 KB, treat these as three separate constraints. Crop to 4:3 if necessary, resize to 1200 x 900 and export JPG, then use the KB reducer for the byte limit. Its compression may reduce dimensions when needed; recheck all requirements on the final output.
Does JPG to PNG improve quality?
Converting JPG to PNG avoids adding another JPEG encoding stage to the decoded image. It does not remove existing JPEG artifacts, sharpen a blurry picture, or make its background transparent. A photographic PNG may be substantially larger than the JPEG source.
Does PNG to JPG always save space?
No. JPEG often works well for photos, but simple graphics can already compress well as PNG. Text and thin lines can develop artifacts during JPEG encoding. Try the PNG to JPG converter, inspect the preview, and compare actual output bytes. Keep PNG when preserving transparent pixels matters.
Format conversion is different from resizing
Changing the encoding does not inherently change the number of pixels. Nor does a new DPI tag give a picture more detail. Inspect dimensions with the dimensions checker, and use the print pixel chart to plan physical output.
Sources and scope
Format capabilities follow the MDN image file type and format guide, reviewed October 12, 2026. Examples describe ToolFoundry workflows, rather than measured compression benchmarks. Actual bytes, visual quality, and compatibility depend on the source image and receiving application.