JPG is mature and broadly compatible. WebP is a modern web-oriented format with flexible compression and current browser support.
What should you consider?
Choose JPG when broad compatibility is the priority. Choose WebP when your website workflow supports it and delivery efficiency matters.
Practical workflow
Start with the destination requirement, make a copy rather than overwriting an important original, and compare the output at the size where it will actually be used. If the file is still too large, consider whether resizing, compression or a different format solves the real problem.
Related tool
Tip: The smallest file is not automatically the best file. Compatibility and visible quality matter too.