estimate vs calculate

estimate is a noun but calculate is not a noun.

Word	Noun	Adjective	Verb	Adverb
estimate	Yes	No	Yes	No
calculate	No	No	Yes	No

As verbs, calculate is a hypernym of estimate; that is, calculate is a word with a broader meaning than estimate:

Other hypernyms of estimate include cipher, compute, cypher, figure, reckon, work out.

As verbs, estimate and calculate are synonyms defined as:

Other synonyms of estimate include count on, figure, forecast, reckon.

estimate (noun)	calculate (noun)
a judgment of the qualities of something or somebody
an approximate calculation of quantity or degree or worth
the respect with which a person is held
a document appraising the value of something (as for insurance or taxation)
a statement indicating the likely cost of some job

estimate (verb)	calculate (verb)
judge tentatively or form an estimate of (quantities or time)	make a mathematical calculation or computation
judge to be probable	specifically design a product, event, or activity for a certain public
	judge to be probable
	have faith or confidence in
	predict in advance
	keep an account of