United Flight 521 Deals & Information (2025/2026)

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United Flight 521 Route Deals From $65

The cheapest prices found with in the last 7 days for return flights were $108 and $65 for one-way flights to Newark Liberty Intl. Airport for the period specified. Prices and availability are subject to change. Additional terms apply.

Tue, Sep 23 - Tue, Sep 30
BOS
Logan Intl.
EWR
Newark Liberty Intl. Airport
$108 Roundtrip, found 19 hours ago
$108
Roundtrip
found 19 hours ago
Select United flight, departing Tue, Sep 23 from Logan Intl. to Newark Liberty Intl. Airport, returning Tue, Sep 30, priced at $108 found 19 hours ago
Mon, Oct 6 - Wed, Oct 8
BOS
Logan Intl.
EWR
Newark Liberty Intl. Airport
$121 Roundtrip, found 17 hours ago
$121
Roundtrip
found 17 hours ago
Select United flight, departing Mon, Oct 6 from Logan Intl. to Newark Liberty Intl. Airport, returning Wed, Oct 8, priced at $121 found 17 hours ago
Sun, Sep 21 - Tue, Sep 23
BOS
Logan Intl.
EWR
Newark Liberty Intl. Airport
$122 Roundtrip, found 21 hours ago
$122
Roundtrip
found 21 hours ago
Select United flight, departing Sun, Sep 21 from Logan Intl. to Newark Liberty Intl. Airport, returning Tue, Sep 23, priced at $122 found 21 hours ago
Mon, Oct 6 - Wed, Oct 8
BOS
Logan Intl.
EWR
Newark Liberty Intl. Airport
$126 Roundtrip, found 17 hours ago
$126
Roundtrip
found 17 hours ago
Select United flight, departing Mon, Oct 6 from Logan Intl. to Newark Liberty Intl. Airport, returning Wed, Oct 8, priced at $126 found 17 hours ago
Mon, Oct 6 - Wed, Oct 8
BOS
Logan Intl.
EWR
Newark Liberty Intl. Airport
$127 Roundtrip, found 17 hours ago
$127
Roundtrip
found 17 hours ago
Select United flight, departing Mon, Oct 6 from Logan Intl. to Newark Liberty Intl. Airport, returning Wed, Oct 8, priced at $127 found 17 hours ago
Mon, Oct 6 - Wed, Oct 8
BOS
Logan Intl.
EWR
Newark Liberty Intl. Airport
$132 Roundtrip, found 17 hours ago
$132
Roundtrip
found 17 hours ago
Select United flight, departing Mon, Oct 6 from Logan Intl. to Newark Liberty Intl. Airport, returning Wed, Oct 8, priced at $132 found 17 hours ago
Tue, Nov 4 - Tue, Nov 11
BOS
Logan Intl.
EWR
Newark Liberty Intl. Airport
$137 Roundtrip, found 1 day ago
$137
Roundtrip
found 1 day ago
Select United flight, departing Tue, Nov 4 from Logan Intl. to Newark Liberty Intl. Airport, returning Tue, Nov 11, priced at $137 found 1 day ago
Fri, Sep 26 - Mon, Sep 29
BOS
Logan Intl.
EWR
Newark Liberty Intl. Airport
$142 Roundtrip, found 1 hour ago
$142
Roundtrip
found 1 hour ago
Select United flight, departing Fri, Sep 26 from Logan Intl. to Newark Liberty Intl. Airport, returning Mon, Sep 29, priced at $142 found 1 hour ago
Mon, Oct 6 - Wed, Oct 8
BOS
Logan Intl.
EWR
Newark Liberty Intl. Airport
$143 Roundtrip, found 17 hours ago
$143
Roundtrip
found 17 hours ago
Select United flight, departing Mon, Oct 6 from Logan Intl. to Newark Liberty Intl. Airport, returning Wed, Oct 8, priced at $143 found 17 hours ago
Thu, Sep 18 - Fri, Sep 19
BOS
Logan Intl.
EWR
Newark Liberty Intl. Airport
$145 Roundtrip, just found
$145
Roundtrip
just found
Select United flight, departing Thu, Sep 18 from Logan Intl. to Newark Liberty Intl. Airport, returning Fri, Sep 19, priced at $145 just found

Frequently asked questions

What route does flight number UA521 take?
UA521 travels from John F. Kennedy Intl. Airport (JFK) to San Francisco, CA Airport (SFO-San Francisco Intl.) directly. This service usually takes 6 hours and 35 minutes.
What terminal does UA521 fly out of?
Flights between JFK and San Francisco, CA Airport (SFO-San Francisco Intl.) are served by UA521, and travelers with a seat booked on this route normally take off from Terminal 7.
What kind of plane is on flight number UA521?
The Boeing 767-300 is the plane that's mostly used for flight number UA521. This flight nearly always heads off from New York, NY Airport (JFK-John F. Kennedy Intl.) and arrives at San Francisco Airport.
If I am not able to travel due to COVID-19, can I change my flight to a later date?
For more info about changing your UA521 flight with Travelocity, please visit our Customer Service Portal.