Charlotte - Recommended Image Sizes
Featured Image Size
For your featured images, images should be no smaller than 1000x850px. Larger is fine. That size will ensure your images display correctly in all areas of the theme (front page, blog page, category pages, etc).
Post Image Size
The width of the blog post column depends on which layout you're using:
- Full-width layout (no sidebar): 950px
- Sidebar layout: 750px
For the clearest possible display, we recommend uploading images roughly twice the post column (1500 to 1900px).
If page speed is a concern, then you can upload images right at the post column size (950/750px). Larger images won't affect your page speed all that much, unless you have a huge number of images in one post.