4 hr 25 min is the shortest flight time from Chicago to San Francisco.

The cheapest days to fly are usually in October. Typical prices range from $115 to $185.

The best round-trip deal recently found on Google Flights from Chicago to San Francisco was with Frontier from $49. The best one-way deal was with Frontier from $19.

There are direct flights from Chicago to San Francisco on a daily basis.

Southwest, Frontier, United, American and Alaska fly direct from Chicago to San Francisco.

The cheapest round-trip flight from Chicago to San Francisco starts at $49 from Sat, Sep 21 to Fri, Sep 27. The cheapest one-way flight starts at $19 and departs on Sat, Sep 21.

Apr–Dec is when most people visit San Francisco, with crowds peaking in summer. Although average temperatures are higher then, mornings and evenings often have damp, chilly fog. In summer, street fairs and cultural institutions offer free outdoor entertainment. Winter visitors will find the opera and ballet seasons in full swing. Major annual events include Chinese New Year (Feb), Bay to Breakers footrace (May), San Francisco Pride parade and festival (Jun), and San Francisco Fleet Week (Oct).

It's easy to use Google Flights to find the cheapest days to fly from Chicago to San Francisco.
Just click the Departure label near the top of the page to open the calendar. Choose a start date and a return date to see how the round-trip fare changes on those specific days.
Adjust the trip type to see one-way fares. The cheapest available flights are highlighted and easy to spot. Once you settle on dates, click the Search button to see flight options and book the deal.

You can also turn on price tracking to get alerts if the price changes for a route or flight.