Singapore is 16 hours ahead of San Diego during standard time (or 15 hours during PDT). San Diego uses Pacific Time (PT, UTC-8/-7) while Singapore uses Singapore Standard Time (SGT, UTC+8). When it's 12:00 PM in San Diego, it's 4:00 AM the next day in Singapore.
Singapore does not observe daylight saving time, so the difference varies between 15 and 16 hours depending on whether San Diego is on PST or PDT.
Best calling time: 5:00 PM - 7:00 PM San Diego time. This corresponds to 9:00 AM - 11:00 AM the next day in Singapore, catching morning business hours.
San Diego's biotech and technology companies have growing partnerships with Singapore. The city's port also handles significant trade with Southeast Asia. Evening calls from California reach Singapore's morning business hours.