tinymce-docs-4x/_includes/configuration/height.md

height

Set the height of the editable area in pixels.

Note that this sets the height of the editable area only. It does not include the space required for the menubar, toolbars or status bar.

Type: Number

Example:

tinymce.init({
  selector: "textarea",  // change this value according to your html
  height : 300
});