$178 Cheap United flights Washington (IAD) to Cancun (CUN)

Grab affordable round-trip United Airlines flights from $379 from IAD to CUN by sorting your results from "Price (lowest to highest)" on Expedia. Or look for deals from $178 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.

Getting the best United Airlines deals from IAD to CUN often comes down to timing. You can save 17% on international flights when you book 18 to 29 days before takeoff instead of four to five months ahead. What's more, you can pocket 17% on average by buying your fare on a Sunday rather than a Friday, which is often the most expensive day to book.* It's a good idea to start checking out flights about one month before your travel dates.*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.

Departing IAD at 8:30AM UTC-5, the earliest United Airlines flight to CUN arrives at 12:20PM UTC-5. Flying earlier in the day means you're less likely to encounter delays or cancellations.* Don't like early starts? The last United Airlines flight from IAD to CUN departs at 12:50PM UTC-5 and touches down at 4:40PM UTC-5.*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.

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