Formula
Sum of (Resolution time - Ticket open time) / Number of resolved tickets
How to measure
Timestamp ticket creation and resolution for every closed ticket, then average the elapsed time across the period.
Why track it
Resolution time directly affects customer effort and satisfaction, and tracking it by issue type reveals which problems need process or product fixes.
Example
Billing-related tickets take an average of 3 days to resolve, far longer than the 4-hour average for password resets.