Shanghai is 16 hours ahead of San Francisco during standard time (or 15 hours during PDT). San Francisco uses Pacific Time (PT, UTC-8/-7) while Shanghai uses China Standard Time (CST, UTC+8). When it's 12:00 PM in San Francisco, it's 4:00 AM the next day in Shanghai.
China does not observe daylight saving time, so the difference varies between 15 and 16 hours depending on whether San Francisco is on PST or PDT.
Best calling time: 5:00 PM - 7:00 PM San Francisco time. This corresponds to 9:00 AM - 11:00 AM the next day in Shanghai, catching Chinese morning business hours.
San Francisco and Shanghai are both major financial and tech centers. Shanghai is China's business capital with a growing tech scene. Many Silicon Valley companies have significant operations in Shanghai. Direct flights connect them in about 12-13 hours.