Server’s (PHP) and client’s (JavaScript) date & time

Server

Date/time : Sat, 16 Feb 2019 23:26:01 UTC/GMT
2019-02-17T00:26:01+0100 [ISO, local]
Time zone : CET; Vienna, Austria [+1 hour to UTC/GMT]
UNIX Epoch: 1,550,359,561

Client

To get the time difference navigate to the Time Zone Converter.
In the 1^st pulldown menu [From Time Zone:] select [your location].
In the 2^nd pulldown menu [To Time Zone:]   select [Austria - Europe/Vienna].
Click Convert Time Now
See the Converter Results at the top of the page.
You have to calculate the time difference manually (first line – second line).Example:
Your local Date: February 02 2018; Time: 15:30:00
From [Asia/Kolkata] to [Europe/Vienna] gives
  15:30:00 Thursday February 2, 2018 in Asia/Kolkata converts to
  11:00:00 Thursday February 2, 2018 in Europe/Vienna
Hence, the time difference for your profile is 15:30 – 11:00 = +4:30.