Does a mermaid petticoat change length of dress?

Adding a mermaid petticoat willchange the length of a dress. Just like if you were to take a full skirt and hold it out on each side, it will make the dress shorter on the sides and look shorter all the way around. Make sure you choose a dress that has allowances so that the length of the dress is still appropriate. Unlike a ball gown that adds volume from the waist down, mermaid style adds more of an outward poof.

Hope this helps!