WordPress automatically generates multiple image sizes when you upload, but starting with properly sized source images gives the best quality. WordPress default sizes are thumbnail (150x150), medium (300x300), medium-large (768xAuto), and large (1024x1024).
For featured images, most WordPress themes recommend 1200x628 (Open Graph compatible) or the theme-specific featured image size. Check your theme documentation for exact recommendations.
With ImgTools, resize your images before uploading to WordPress. This gives you control over the quality and reduces the processing load on your WordPress server. Upload images at the largest display size needed (typically 1200-1600px wide for full-width content).
Save as JPEG at 80-85% quality. WordPress will further compress images, so uploading at slightly higher quality ensures the final result is sharp.
All processing happens in your browser. No plugin installation needed.