$481 Cheap Frontier Airlines flights Grand Rapids (GRR) to Islip (ISP)

You'll find affordable round-trip Frontier Airlines flights from $155 from GRR to ISP by filtering your results from "Price (lowest to highest)" on Expedia. Or look for options from $481 for a one-way journey.**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 cheaper fares on Frontier Airlines flights from Gerald R. Ford Intl. Airport (GRR) to MacArthur Airport (ISP). You can save 25% by booking your domestic flight 34 to 86 days in advance compared to last-minute reservations made 6 to 12 days out. You could also reduce 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 your timing spot on, 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 departures from GRR to ISP with Frontier Airlines, filter your results by "Early Morning" and "Morning." Choosing an early flight generally means you'll experience fewer 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.

Journey from GRR to ISP with Frontier Airlines and you'll enjoy a range of perks including a rewarding loyalty program. When you book through Expedia as a Frontier Miles and One Key™ member, you could also earn OneKeyCash™* to use on select future travel purchases.*OneKeyCash™ disclaimer - OneKeyCash™ is not redeemable for cash and can only be used on Expedia, Hotels.com and Vrbo.