There are four formal ways to amend the US Constitution: 1) a two-thirds vote in both houses of Congress and ratification by three-fourths of state legislatures; 2) a proposal by Congress and ratification by state conventions in three-fourths of states; 3) a proposal by a national convention called by Congress and ratification by three-fourths of states; and 4) a proposal by national convention and ratification by state conventions in three-fourths of states. The Constitution can also be informally amended through legislative, executive, judicial, party practices, and customs that change how it functions without changing the text.