Fit featured images and content images to the optimal size for blogs and websites.
Select an option to continue to cropping.
Drag the image to reposition it
JPEG does not support transparency; transparent areas will use a white background.
Uploading larger images than necessary is one of the most common causes of a slow-loading website. 1920×1080 px is enough for full-width banners, and 1200×800 px covers almost any in-article content image.
It helps, since you're reducing file size, but for best results combine it with additional compression in your CMS or optimization plugin.
JPG for photographs, PNG only if you need transparency or sharp lines (screenshots, logos).