How long did it take to write the Declaration of Independence?

Although it is based on other historical documents, and may have been considered by Thomas Jefferson and others prior to its proposal, the period of its drafting is fairly certain. It was drafted by Thomas Jefferson between June 11 and June 28, 1776, and revised by members of Congress including Benjamin Franklin and John Adams. It was adopted on July 4, 1776.
there is no amount of time that it took but it was finished in July 4, 1776
It took Thomas Jefferson 17 days to write the Declaration of Independence.