How to change media size presets?

It’s not recommended to change the WordPress core. Your best bet is to find or create a plugin that does what you want. But I’m not sure what you’re asking for is necessary… there’s some flexibility with how you display images once you’ve inserted them into a post/page.

You can always edit the image after you insert it and use the Advanced Settings tab to specify a width/height. It’s not a true “resize,” and it’s obviously not recommended if there’s a drastic size difference between the original file and the tweaked one, but it works in a pinch.

Also good to note: If you’ve changed the Media Settings, any images previously uploaded to the Media Library will not be resized automatically. You either need to upload the same images again to get them at the new sizes or use a plugin like Regenerate Thumbnails.

Well, thanks for the reply.

But I would prefer that my client did not mess with the pictures size, so
if there was a way to create the size presets , then when they uploaded,
they just needed to select Thumbnail, Medium or Large, and it would fit
perfect on the HTML div, without them to have to go into the html code
to specify a width/height.

You see, I have all the design made with HTML/CSS, and the div′s where
supposed to be the content from the wordpress back-end have
their own specific size.
But I just can′t figure out why on uploading some media , its goes over the
div size, even if the _loop is constrain inside the div.

Confused? me too ??

You could set the div style to overflow: hidden.

There might be a plugin that will crop to an exact size upon upload for Thumbnail, Medium and Large sizes. WP natively crops the Thumbnail if you set that option, but the other two will auto-resize proportionally based on the longest side of the uploaded file and your Media Settings.

Thanks for the help!

The overflow:hidden can do the trick for now! ??

Still Iam going to keep gather information how to create media size presets.

Thanks again.