Ah, I see you just started restoring that 1TB monster and now everyone wants to know when it's going to be finished, where you're at in the process, etc. Fear not, Microsoft is very good at making up fictional numbers for us to use as rough estimates! I usually add 10-20% on top of these estimates just incase the database gremlins wander by to ruin your day again. Or incase you encounter "storage issues."
select percent_complete AS [PercentComplete] ,estimated_completion_time/1000.0/60.0 AS [RemainingMinutes] ,total_elapsed_time/1000.0/60.0 AS [ElapsedMinutes] ,(estimated_completion_time+total_elapsed_time)/1000.0/60.0 AS [TotalMinutes] ,DATEADD(MILLISECOND, estimated_completion_time, GETDATE()) AS [EstimatedTimeOfCompletion] ,st.text AS [CommandSQL] from sys.dm_exec_requests r cross apply sys.dm_exec_sql_text(r.sql_handle) st WHERE command LIKE '%RESTORE DATABASE%'