The standard convention for writing artwork dimensions is to list them as height x width (x depth, if applicable for three-dimensional works). This format is widely accepted in the art world, including galleries, museums, and art publications.

 

So, you should write the dimensions with the height first, followed by the width, and depth if necessary. For example:

For a painting: 24 x 18 inches
For a sculpture: 24 x 18 x 12 inches
 

This convention helps maintain consistency and clarity in the presentation of art dimensions.