Karachi is 4.5 hours behind Adelaide
Best overlap: 12:30 PM to 6:30 PM in Adelaide is 8:00 AM to 2:00 PM in Karachi.
Your shared working hours run 12:30 PM to 6:30 PM in Adelaide (8:00 AM to 2:00 PM in Karachi). Karachi is 4.5 hours behind Adelaide, and with 6 hours of overlap you can even run back-to-back calls without stepping outside business hours. Heads up: because Adelaide changes its clocks and Karachi doesn't, the difference moves by an hour twice a year. Confirm the overlap around the DST switch.