every little bit helps
Any contribution can be useful, as in He can only give us one day, but every little bit helps. This expression, with slightly different wording (everything helps), dates from the late 1500s.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.