off the top of my head

así de improviso, sin pensarlo mucho

• Off the top of my head, I'd say we have around fifty customers.
• Off the top of my head, I can't remember his last name.
• She gave an answer off the top of her head during the interview.

This idiom is used in informal situations when someone gives an immediate answer without much thought. It is common in casual conversation, especially when emphasizing that the information may not be entirely accurate.

A common mistake is saying 'out of the top of my head', which is not English. The correct phrase is 'off the top of my head'.

• back to square one
  volver a empezar, vuelta a empezar
• to make a long story short
  para resumir, en resumen
• out of the blue
  de la nada, de repente
• by the way
  por cierto, a propósito