What does 'Back-of-the-envelope calculation' mean?

A back of the envelope calculation is a figure that was arrived at quickly or by using estimation--as if someone had grabbed the first scrap of paper they found and made a quick guess.

• Category: General
• Contributed By: Amanda

Idioms similar to 'Back-of-the-envelope calculation'

• Push the envelope
• Back to back
• Back number
• Back burner
• Take a back seat
• Get back on the horse that bucked you
• Cast your mind back
• Back to the drawing board