$338 Cheap Delta flights Philadelphia (PHL) to Castries (SLU)

Make use of the "Price (lowest to highest)" filter on Expedia to look for cheap Delta Air Lines round-trip flights from $557 from PHL to SLU. Affordable one-way fares from $338 are also on offer.**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.

Scoring the best Delta Air Lines deals from PHL to SLU is typically all about timing. You can save 17% on international flights when you book 18 to 29 days before takeoff instead of four to five months ahead. To top it off, you can pocket 17% on average by buying your fare on a Sunday compared to a Friday, which is usually the most expensive day to book.* It's smart to kick off your flight search about one month before your departure date.*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.

Sort your results by "Early Morning" and "Morning" to browse the earliest departures from PHL to SLU. Heading off early means you're less likely to experience cancellations.**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.

Traveling from PHL to SLU with Delta Air Lines means enjoying a host of benefits, such as an excellent in-flight experience and a rewarding loyalty program. Plus, when booking through Expedia, One Key™ members can earn OneKeyCash™* to spend on select future travel purchases. That's in addition to the Delta SkyMiles points you can earn with Delta Air Lines.*OneKeyCash™ disclaimer - OneKeyCash™ is not redeemable for cash and can only be used on Expedia, Hotels.com and Vrbo.