Find SQL Server Page Life Expectancy

-- Page Life Expectancy (PLE) value for default instance

SELECT cntr_value AS [Page Life Expectancy]

FROM sys.dm_os_performance_counters WITH (NOLOCK)

WHERE [object_name] = N'SQLServer:Buffer Manager' -- Modify this if you have named instances

AND counter_name = N'Page life expectancy' OPTION (RECOMPILE);

-- PLE is a good measurement of memory pressure.

-- Higher PLE is better. Watch the trend, not the absolute value.