A.T. Robertson Commentary Revelation 21:17

"And he measured the wall thereof, a hundred and forty and four cubits, [according to] the measure of a man, that is, of an angel." — Revelation 21:17 (ASV)

A hundred and forty and four cubits (εκατον τεσσερακοντα τεσσαρων πηχων). Another multiple of 12 (12x12=144) as in 7:4; 14:1. It is not clear whether it is the height or the breadth of the wall that is meant, though υψος (height) comes just before. That would be 216 feet high (cf. verse 12), not enormous in comparison with the 7,000,000 feet (1500 miles) height of the city.

According to the measure of a man, that is, of an angel (μετρον ανθρωπου, ο εστιν αγγελου). No preposition for "according to," just the accusative case of general reference in apposition with the verb εμετρησεν. Though measured by an angel, a human standard was employed, man's measure which is angel's (Bengel).