Reykjavik is 8 hours behind Shanghai
Best overlap: 4:00 PM to 6:00 PM in Shanghai is 8:00 AM to 10:00 AM in Reykjavik.
For the smoothest call, aim inside 4:00 PM to 6:00 PM in Shanghai, i.e. 8:00 AM to 10:00 AM in Reykjavik. Overlap is at a premium — roughly 2 hours — so claim 4:00 PM in Shanghai (8:00 AM in Reykjavik) for recurring calls and keep them on time.