$129 Cheap Delta flights Seattle (SEA) to Philadelphia (PHL)

You'll find cheap round-trip Delta Air Lines flights from $269 from SEA to PHL by sorting your results from "Price (lowest to highest)" on Expedia. Or look for deals from $129 for a one-way trip.**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.

For cheap Delta Air Lines fares from Seattle - Tacoma Intl. Airport (SEA) to Philadelphia Intl. Airport (PHL), start searching one to three months before your planned departure. Securing domestic flights 34 to 86 days in advance could save you 25% compared to booking just 6 to 12 days ahead. The day you book can also affect how much you pay. Sunday is typically the cheapest, while Monday is often the most expensive for domestic flights. You can save 6% on average by booking on a Sunday.**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.

Browse Delta Air Lines's earliest flights from SEA to PHL by checking the "Morning" and "Early Morning" filters. Not only will you arrive at your destination sooner, early departures are also 20% less likely to be canceled.**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.

Delta Air Lines makes traveling from SEA to PHL enjoyable with an excellent in-flight experience and a rewarding loyalty program. You could even start collecting points with Delta SkyMiles. Remember to sign up to our free One Key™ rewards program to earn OneKeyCash™*, which can be redeemed on future trips.*OneKeyCash™ disclaimer - OneKeyCash™ is not redeemable for cash and can only be used on Expedia, Hotels.com and Vrbo.