how long is a piece of string

Meaning

1. how long is a piece of string?

   used to say that there is no definite answer to a question

   'How long will it take?''How long's a piece of string?'

From the same entry

• as long as your arm
• at long last
• at the longest
• by a long way
• go back a long way
• go a long way
• have come a long way
• have a long way to go
• in the long run
• it's a long story
• the long arm of
• the long and short of it