off the top of head

Related to off the top of head: Off the Top of My Head

off the top of (one's) head

From memory or without much or careful consideration. A: "How much can we expect to earn this quarter?" B: "Off the top of my head, it should be around $200,000, but I'll have to check the figures when I get to the office." I know of two people who are coming off the top of my head, but I'm pretty sure more said they'd be here. John can list the capital cities of all 50 states off the top of his head.
See also: head, of, off, top
Farlex Dictionary of Idioms.

(right) off the top of one's head

Fig. without giving it too much thought or without precise knowledge. Mary: How much do you think this car would be worth on a trade? Fred: Well, right off the top of my head, I'd say about a thousand. Tom: What time does the morning train come in? Bill: Off the top of my head, I don't know.
See also: head, of, off, top
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

off the top of (one's) head

Informal
In an impromptu way: She recited the poem off the top of her head.
See also: head, of, off, top
American Heritage® Dictionary of the English Language, Fifth Edition.
See also:
  • on mature consideration
  • on mature reflection/consideration
  • be careful
  • if you can't be good, be careful
  • puzzle out
  • puzzle out (something)
  • snap decision
  • nut out
  • rubber stamp
  • snap judgment