add up vs summate

add up and summate both are verbs.

Word	Noun	Adjective	Verb	Adverb
add up	No	No	Yes	No
summate	No	No	Yes	No

As verbs, add up and summate are synonyms defined as:

Other synonyms of add up include add, add together, sum, sum up, tally, tot, tot up, total, tote up.

add up (verb)	summate (verb)
determine the sum of	determine the sum of
be reasonable or logical or comprehensible	form or constitute a cumulative effect
to measure up to in kind or quality
add up in number or quantity