I would like to figure out the service ceiling for Cessna 172N and I couldn't find it anywhere in the POH.
Where can I find it? In POH or somewhere else? If in POH, please post a snapshot of it.
It is in the Pilots Operating Handbook allright.
As @Dave pointed out, this value can change depending on configuration and other limitation/alterations.
It is in the pilot handbook, before the title page [PDF], under "performance-specifications"