Reykjavik is 2 hours behind Cairo
Best overlap: 10:00 AM to 6:00 PM in Cairo is 8:00 AM to 4:00 PM in Reykjavik.
The overlap falls at 10:00 AM to 6:00 PM in Cairo, or 8:00 AM to 4:00 PM if you're in Reykjavik. Reykjavik is 2 hours behind Cairo, and with 8 hours of overlap you can even run back-to-back calls without stepping outside business hours. Heads up: because Cairo changes its clocks and Reykjavik doesn't, the difference moves by an hour twice a year. Confirm the overlap around the DST switch.