In view of the fact that there are no direct flights from Moscow to San Francisco, the travel time will depend heavily on the selected airlines and route. For example, if you fly Delta with one change in New York, the net flight time to your destination will take 17 hours and 45 minutes plus a docking time of about 4 hours. The total travel time is approximately 22 hours

If you fly to New York by Aeroflot planes, and from it to San Francisco by US Airways, the total travel time is reduced to 18-19. Each of the flights is shorter by half an hour, and docking by 2.

You can change to Los Angeles, to which Aeroflot or Delta is driving for 13 hours and where from San Francisco US Airways or Alaska Airlines fly an hour with little. The total travel time in this case will be approximately 16-17 hours.

The rest of the options, mostly less convenient and longer, even without the connection time. If you fly through Dubai, then only in the air you have to spend about 21 hours, through Seoul - 18 hours, and via Hong Kong - 22 hours