come to think of it
Remember or consider on reflection. For example, Come to think of it, I've got to send in my order now, or I was going to lend him a saw, but come to think of it, he already has one. [First half of 1800s]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.