When you're submitting an order request online, you'll be asked for your art's dimensions in whole inches. When measuring your art, you can round up to the nearest inch. So 20.5" can be entered at 21". The sizing entered when placing your order only needs to be approximate.
Our design experts will hand-measure your artwork down to an 1/8" when it is received in our studio so we can craft a completely custom frame for the exact dimensions of your piece.