recommended size for featured images

1200 pixels wide.

Hi,

Thanks. Where did you find that size info?

The recommended Featured Image size is 1200 wide.

its present on TwentySixteen official page (right at bottom )
https://theme.wordpress.com/themes/twentysixteen/

that is on wordpress.com
is it the same on www.ads-software.com?

I believe so, but it will only display a 1200 wide image if you have no sidebar, otherwise it is 840 px wide. If you have a sidebar showing, you would be better to size your images to 840 wide before uploading