Abstract: A necklace sizer useful for determining a necklace size for a prospective wearer employs a flexible measuring chain having a clasp at one end which is detachably attachable to the flexible measuring chain to provide a closed-loop measuring chain of selected length. The flexible measuring chain can be made up of a number of measuring links and at least one length-indicating tag. The measuring links, which can be ring-like are each of known length along the measuring chain and each measuring link can have the same length. The at least one length-indicating tag can be connected between and to each of two of the measuring links, can bear a length-indicating marking and can also have a predetermined length. Optionally, the at least one length-indicating tag can be apertured to receive the clasp. Useful embodiments of the necklace sizer can provide easily made and accurate size determinations. Some embodiments can simulate the look and feel of a necklace around the wearer's neck.