The size dimensions given are for the full design. The first number is always the width (or, side-to-side), from the furthest left point of the design, to the furthest right. The second number is always the height (or, up-and-down), from the highest point of the design, to the lowest.
In this first example, which includes multiple lines of text and an embellishment, you can see that the height (second number) is inclusive of the whole design, and not individual lines or letters.
In this second example, which only has one line of text, you can see that the height (second number) starts at the top of the tallest letter (often letters with ascenders, such as: b, d, f, h, etc.), and extends to the bottom of the lowest letter (usually letters with descenders, such as y, j, g, etc.), and does not represent the height of any individual letters. It is the measurement of the whole design.
Please measure your space before ordering to ensure the size you choose will fit well in your space. Keep in mind that the sizes we offer for each design range considerably, from very small (to fit on a plaque or door) to very large (to extend the full width of a king size bed, for example). Not all sizes will work well in all applications, so it's important to measure your space and choose the size which will compliment the space and the room.
Someday I'll swim with mermaids.