The short answer
Use WebP for modern web delivery when your browser and publishing stack support it. Use JPG when a photograph must work in older software, office documents, print services, or upload forms that reject WebP.
Neither extension guarantees a smaller or better-looking file. Dimensions, encoder, quality setting, and image content all matter. Compare representative outputs in the actual workflow.
Compression and image quality
JPG uses lossy compression designed around photographic content. WebP supports both lossy and lossless modes and can encode an alpha channel. At comparable visual quality, WebP is often efficient, but that does not mean every converted file will be smaller.
Conversion between lossy formats is a new generation. It cannot recover source detail, and aggressive settings may reveal ringing, blocking, or smearing around texture and edges.
- Keep the highest-quality original as the source of future derivatives.
- Resize to real display dimensions before relying only on lower quality.
- Judge detail at the intended display size and at 100% for critical assets.
Transparency and animation
WebP can carry transparency; baseline JPG cannot. Converting a transparent WebP to JPG requires blending transparent pixels onto a solid background. PNG is the more direct replacement when alpha must remain.
WebP can also contain animation. A still-image converter does not preserve the animation timeline, so use a dedicated animation workflow for animated sources.
Compatibility and editing
All current major browsers support WebP. Compatibility gaps are more likely in older desktop applications, legacy content systems, document pipelines, and specialist hardware. JPG remains one of the safest interchange formats for photographs.
For repeated editing, keep a lossless or high-quality master. Both a lossy WebP and a JPG are delivery formats rather than ideal multigeneration working files.
A practical decision rule
If the destination accepts WebP and the file meets your quality and size needs, there is no reason to convert it. Convert to JPG for compatibility, to PNG for transparency or lossless decoded pixels, and from JPG or PNG to WebP when you are preparing tested web derivatives.