Question

at the outside How long will it take to get there? Three hours at the outside.

Accepted Answer

When talking about the length of time or amount of money necessary to do something, at the outside indicates the highest estimate or the largest amount.

Phrase/Idiom	at the outside
Definition	When talking about the length of time or amount of money necessary to do something, at the outside indicates the highest estimate or the largest amount.
Example	How long will it take to get there? Three hours at the outside.

Talking Length Time Amount Money Highest Estimate Largest