Colombo is 2.5 hours ahead of Cairo
Best overlap: 8:00 AM to 4:00 PM in Cairo is 10:30 AM to 6:30 PM in Colombo.
Plan around 8:00 AM to 4:00 PM in Cairo, which is 10:30 AM to 6:30 PM in Colombo, to catch everyone during office hours. Colombo is 2.5 hours ahead of Cairo, but you'd hardly notice — 8 hours of shared hours makes this feel like working in neighbouring time zones. Don't be caught out by clock changes — Cairo observes daylight saving and Colombo doesn't, so the offset varies by an hour through the year.