A lot vs. Alot: 9 Grammatical Pitfalls
1863, "devised beforehand," past participle adjective from calculate. Earlier, "suited, apt" (1722).
1560s, "to compute, to estimate by mathematical means," from Latin calculatus, past participle of calculare "to reckon, compute," from calculus (see calculus). Meaning "to plan, devise" is from 1650s. Replaced earlier calculen (mid-14c.), from Old French calculer. Related: Calculable.