St. Louis (STL) to San Juan (SJU) flight deal from $225 USD in economy class

UAUnited Airlines

Round Trip•Economy

STL

Lambert-Saint Louis International Airport

St. Louis, United States

SJU

Luis Muñoz Marín International Airport

San Juan, Puerto Rico

$522 USD

-57%$225 USD

Verified Dec 1, 2025 at 5:21 AM

January 2026

Today

Mon

Tue

Wed

Thu

Fri

Sat

Sun

29$752 30$625 31$358 1$342 2$448 3$362 4$338 5$338 6$293 7$339 8$358 9$348 10$407 11$293 12$248 13$248 14$415 15$490 16$467 17$330 18$225 19$225 20$225 21$225 22$339 23$398 24$293 25$225 26$225 27$225 28$225 29$302 30$398 31$293 1

Rare Availability

5% of dates checked are available within 10% of the lowest price

Friday, January 9th, 2026

10 round-trip options

Returning

Wed, Jan 14, 2026•5 Day Trip

$348 USD

Google Flights

Returning

Thu, Jan 15, 2026•6 Day Trip

$348 USD

Google Flights

Returning

Fri, Jan 16, 2026•7 Day Trip

$416 USD

Google Flights

Returning

Sat, Jan 17, 2026•8 Day Trip

$438 USD

Google Flights

Returning

Sun, Jan 18, 2026•9 Day Trip

$648 USD

Google Flights

Returning

Mon, Jan 19, 2026•10 Day Trip

$717 USD

Google Flights

Returning

Tue, Jan 20, 2026•11 Day Trip

$482 USD

Google Flights

Returning

Wed, Jan 21, 2026•12 Day Trip

$371 USD

Google Flights

Returning

Thu, Jan 22, 2026•13 Day Trip

$348 USD

Google Flights

Returning

Fri, Jan 23, 2026•14 Day Trip

$371 USD

Google Flights