Swingin' 60s spiral dress

Truly not sure if this is a dress or a beach cover-up because it would be perfect for both. A vintage polyester wrap dress I picked up in Scotland, this is in mint condition. Double measurements for bust, waist and hips. True it's a wrap so there's some wiggle room for sizing, but not much. It would be best-suited to the below measurements as a maximum. Bust: 16.5 inches Waist: 13 inches Hips: 16.5 inches Arm length: 8 inches Length: 34 inches