Flat irons are like shoes — they’re not one size fits all. Depending on the length and thickness of your hair, the right size iron will straighten your hair more efficiently and decrease the risk of damaging hair, Moticka says.

For short hair: Use an iron with narrow plates ranging in size from 1/2-inch to 1-inch thick. This will allow you to iron smaller sections.

For long hair: Use an iron with wider plates ranging in size from 1 1/2-inches to 2-inches wide so you’re able to cover more surface area in less time.