John Calvin Commentary Exodus 38:21

"This is the sum of [the things for] the tabernacle, even the tabernacle of the testimony, as they were counted, according to the commandment of Moses, for the service of the Levites, by the hand of Ithamar, the son of Aaron the priest." — Exodus 38:21 (ASV)

This is the sum of the tabernacle.³⁰² This is to say that this was the computation, or these were the numbers.

For he gives us to understand that not only was the tabernacle thus at once completed, but its several parts were also numerically distinguished and, as it were, consigned to registers,³⁰³ to be entrusted to the Levites, so that no part of it would be lost.

For the reference here is not so much to the physical structure or architecture of the tabernacle, but rather to its ongoing preservation—namely, that Ithamar the priest deposited its several parts with the Levites, and this was in accordance with the command of Moses.

³⁰² “These are the counted-things.” — things.” — Lat. So also Ainsworth.. So also Ainsworth.

³⁰³ “Afin que les Levites sceussent ce qu’ils devoyent avoir en garde;” in order that the Levites might know what they ought to have in charge. — Fr..