It's harder than that!. . . PLUS it has to be ratified by 2/3rds of all the States. . .
A successful Constitutional Amendment has to pass both houses of Congress by 2/3's and then by ratified by 3/4's of states.
So, right now with 50 states, 3/4's is 37.5. But you can't get half a state. So, a successful Constitutional Amendment has to be ratified by at least 38 states.