Oslo is 1-2 hours ahead of Reykjavik. Reykjavik uses Greenwich Mean Time (GMT, UTC+0) year-round while Oslo uses Central European Time (CET/CEST, UTC+1/+2). When it's 12:00 PM in Reykjavik, it's 1:00 PM in Oslo (winter) or 2:00 PM (summer).
Iceland does not observe daylight saving time, while Norway does. During European summer time (late March to late October), the difference increases to 2 hours.
Best calling time: 9:00 AM - 5:00 PM Reykjavik time. This corresponds to 10:00 AM - 6:00 PM (or 11:00 AM - 7:00 PM in summer) in Oslo, covering business hours.
Both Iceland and Norway are Nordic countries with strong cultural ties. Icelandair connects Reykjavik and Oslo with direct flights taking about 2.5 hours.