United Flight UA645 Deals & Information (2025/2026)

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United Flight 645 Route Deals From $109

The cheapest prices found with in the last 7 days for return flights were $193 and $109 for one-way flights to Sioux Falls Regional for the period specified. Prices and availability are subject to change. Additional terms apply.

Wed, Jul 9 - Sun, Jul 13
DEN
Denver Intl.
FSD
Sioux Falls Regional
$193 Roundtrip, found 3 days ago
$193
Roundtrip
found 3 days ago
Select United flight, departing Wed, Jul 9 from Denver Intl. to Sioux Falls Regional, returning Sun, Jul 13, priced at $193 found 3 days ago
Fri, Sep 5 - Sun, Sep 7
DEN
Denver Intl.
FSD
Sioux Falls Regional
$194 Roundtrip, found 1 day ago
$194
Roundtrip
found 1 day ago
Select United flight, departing Fri, Sep 5 from Denver Intl. to Sioux Falls Regional, returning Sun, Sep 7, priced at $194 found 1 day ago
Wed, Aug 6 - Sat, Aug 9
DEN
Denver Intl.
FSD
Sioux Falls Regional
$197 Roundtrip, found 3 days ago
$197
Roundtrip
found 3 days ago
Select United flight, departing Wed, Aug 6 from Denver Intl. to Sioux Falls Regional, returning Sat, Aug 9, priced at $197 found 3 days ago
Sat, Aug 9 - Sun, Aug 10
DEN
Denver Intl.
FSD
Sioux Falls Regional
$198 Roundtrip, found 3 days ago
$198
Roundtrip
found 3 days ago
Select United flight, departing Sat, Aug 9 from Denver Intl. to Sioux Falls Regional, returning Sun, Aug 10, priced at $198 found 3 days ago
Fri, Sep 5 - Sun, Sep 7
DEN
Denver Intl.
FSD
Sioux Falls Regional
$199 Roundtrip, found 1 day ago
$199
Roundtrip
found 1 day ago
Select United flight, departing Fri, Sep 5 from Denver Intl. to Sioux Falls Regional, returning Sun, Sep 7, priced at $199 found 1 day ago
Thu, Oct 2 - Sun, Oct 5
DEN
Denver Intl.
FSD
Sioux Falls Regional
$214 Roundtrip, found 10 hours ago
$214
Roundtrip
found 10 hours ago
Select United flight, departing Thu, Oct 2 from Denver Intl. to Sioux Falls Regional, returning Sun, Oct 5, priced at $214 found 10 hours ago
Wed, Oct 1 - Sun, Oct 5
DEN
Denver Intl.
FSD
Sioux Falls Regional
$219 Roundtrip, found 10 hours ago
$219
Roundtrip
found 10 hours ago
Select United flight, departing Wed, Oct 1 from Denver Intl. to Sioux Falls Regional, returning Sun, Oct 5, priced at $219 found 10 hours ago
Thu, Oct 2 - Sun, Oct 5
DEN
Denver Intl.
FSD
Sioux Falls Regional
$254 Roundtrip, found 10 hours ago
$254
Roundtrip
found 10 hours ago
Select United flight, departing Thu, Oct 2 from Denver Intl. to Sioux Falls Regional, returning Sun, Oct 5, priced at $254 found 10 hours ago
Thu, Oct 2 - Sun, Oct 5
DEN
Denver Intl.
FSD
Sioux Falls Regional
$258 Roundtrip, found 10 hours ago
$258
Roundtrip
found 10 hours ago
Select United flight, departing Thu, Oct 2 from Denver Intl. to Sioux Falls Regional, returning Sun, Oct 5, priced at $258 found 10 hours ago
Wed, Oct 1 - Sun, Oct 5
DEN
Denver Intl.
FSD
Sioux Falls Regional
$259 Roundtrip, found 10 hours ago
$259
Roundtrip
found 10 hours ago
Select United flight, departing Wed, Oct 1 from Denver Intl. to Sioux Falls Regional, returning Sun, Oct 5, priced at $259 found 10 hours ago
Thu, Oct 2 - Sun, Oct 5
DEN
Denver Intl.
FSD
Sioux Falls Regional
$267 Roundtrip, found 10 hours ago
$267
Roundtrip
found 10 hours ago
Select United flight, departing Thu, Oct 2 from Denver Intl. to Sioux Falls Regional, returning Sun, Oct 5, priced at $267 found 10 hours ago

Frequently asked questions

What route does flight number UA645 take?
UA645 serves multiple routes, but the most common is between FCA and DIA airport. If your flight goes direct, you'll land in around 2 hours and 6 minutes. Multi-stop flights can also use this number, as can services on other routes.
What kind of plane is on flight number UA645?
UA645 is a flight number that is used on many routes. If you've booked a ticket on the most popular one, Glacier Park Intl. Airport (FCA) to Denver Intl. Airport (DEN), chances are you'll be hopping aboard the Boeing 737-800.
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 UA645 flight with Travelocity, please visit our Customer Service Portal.