$129 Cheap United flights Boston (BOS) to San Diego (SAN)

Finding cheap one-way United Airlines flights from BOS to SAN from $129 on Expedia couldn't be simpler --- just filter by "Price (lowest to highest)." Or check out our affordable return fares from $247 for your next exciting getaway.**These prices were available on Expedia within the past 7 days, for flights departing within the next year. Prices and availability are subject to change. Additional terms apply.

Begin your search one to three months ahead of your travel date to get cheap fares on United Airlines flights from Logan Intl. Airport (BOS) to San Diego Intl. Airport (SAN). You can save 25% by booking your domestic flight 34 to 86 days in advance versus last-minute reservations made 6 to 12 days out. You could also cut costs by buying your fare on a Sunday, as it's 6% cheaper on average than a Monday, the most expensive day to book.* Get the timing right, and you can enjoy significant savings on domestic flights.*Ideal booking window recommendation is based on average round-trip ticket prices for January through November for 2024. Best day of the week to book recommendation is based on average round-trip ticket prices for January through October 2024. All data sourced from ARC's global airline sales database.

To find the earliest departure from BOS to SAN with United Airlines, filter your search by "Early Morning" and "Morning." Choosing an early flight usually means cancellations are less likely.**Most reliable time of the day recommendation is based on January through August 2024 flight status data sourced from OAG's global flight data platform.

Offering a rewarding loyalty program, United Airlines is a favorite of many travelers heading from BOS to SAN. Plus, as a United Mileage Plus and One Key™ member booking through Expedia, you could earn OneKeyCash™* on eligible flights on top of your airline miles.*OneKeyCash™ disclaimer - OneKeyCash™ is not redeemable for cash and can only be used on Expedia, Hotels.com and Vrbo.