$307 Cheap Flights from Denver (DEN) to Sidney (SDY)

View $307 flight on Tue, Jun 23, 2026Opens in a new window

Popular airlines from Denver Intl. Airport (DEN) to Sidney, MT (SDY-Sidney-Richland Municipal)

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Cheap Flights from Denver to Sidney (DEN-SDY)

Prices were available within the past 7 days and start at $307 for one-way flights and $481 for round trip, for the period specified. Prices and availability are subject to change. Additional terms apply.

United
Fri, Mar 20 - Sat, Mar 28
DEN
Denver
SDY
Sidney
$481 Roundtrip, found 4 days ago
$481
Roundtrip
found 4 days ago
Select United flight, departing Fri, Mar 20 from Denver to Sidney, returning Sat, Mar 28, priced at $481 found 4 days ago
United
Fri, Mar 20 - Sat, Mar 28
DEN
Denver
SDY
Sidney
$491 Roundtrip, found 4 days ago
$491
Roundtrip
found 4 days ago
Select United flight, departing Fri, Mar 20 from Denver to Sidney, returning Sat, Mar 28, priced at $491 found 4 days ago
United
Fri, Mar 20 - Sat, Mar 28
DEN
Denver
SDY
Sidney
$506 Roundtrip, found 4 days ago
$506
Roundtrip
found 4 days ago
Select United flight, departing Fri, Mar 20 from Denver to Sidney, returning Sat, Mar 28, priced at $506 found 4 days ago
United
Fri, Mar 20 - Sat, Mar 28
DEN
Denver
SDY
Sidney
$526 Roundtrip, found 4 days ago
$526
Roundtrip
found 4 days ago
Select United flight, departing Fri, Mar 20 from Denver to Sidney, returning Sat, Mar 28, priced at $526 found 4 days ago
United
Fri, Mar 20 - Sat, Mar 28
DEN
Denver
SDY
Sidney
$551 Roundtrip, found 4 days ago
$551
Roundtrip
found 4 days ago
Select United flight, departing Fri, Mar 20 from Denver to Sidney, returning Sat, Mar 28, priced at $551 found 4 days ago
United
Fri, Mar 20 - Sat, Mar 28
DEN
Denver
SDY
Sidney
$571 Roundtrip, found 4 days ago
$571
Roundtrip
found 4 days ago
Select United flight, departing Fri, Mar 20 from Denver to Sidney, returning Sat, Mar 28, priced at $571 found 4 days ago
United
Fri, Mar 20 - Sat, Mar 28
DEN
Denver
SDY
Sidney
$635 Roundtrip, found 4 days ago
$635
Roundtrip
found 4 days ago
Select United flight, departing Fri, Mar 20 from Denver to Sidney, returning Sat, Mar 28, priced at $635 found 4 days ago
United
Fri, Mar 20 - Sat, Mar 28
DEN
Denver
SDY
Sidney
$645 Roundtrip, found 4 days ago
$645
Roundtrip
found 4 days ago
Select United flight, departing Fri, Mar 20 from Denver to Sidney, returning Sat, Mar 28, priced at $645 found 4 days ago
United
Fri, Mar 20 - Sat, Mar 28
DEN
Denver
SDY
Sidney
$655 Roundtrip, found 4 days ago
$655
Roundtrip
found 4 days ago
Select United flight, departing Fri, Mar 20 from Denver to Sidney, returning Sat, Mar 28, priced at $655 found 4 days ago
Alaska Airlines
Wed, Jun 10 - Sat, Jun 13
DEN
Denver
SDY
Sidney
$784 Roundtrip, found 3 days ago
$784
Roundtrip
found 3 days ago
Select Alaska Airlines flight, departing Wed, Jun 10 from Denver to Sidney, returning Sat, Jun 13, priced at $784 found 3 days ago

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Frequently asked questions

How much does a flight from Denver Intl. Airport (DEN) to Sidney-Richland Municipal Airport (SDY) cost?
Get a cheap one-way flight from $307 or cheap return flight from $481 from Denver Intl. Airport (DEN) to Sidney-Richland Municipal Airport (SDY) with Expedia. Enter your travel dates and sort by "Price (lowest to highest)" to find our cheapest flight deals on this route.
What is the cheapest month to fly from Denver Intl. Airport (DEN) to Sidney-Richland Municipal Airport (SDY)?
The cheapest month to fly from DEN to SDY is March, when there's less demand. Off-peak season is usually when airlines offer lower prices between these airports.
What is the cheapest airline that flies from Denver Intl. Airport (DEN) to Sidney-Richland Municipal Airport (SDY)?
Expedia's filter tool lets you easily compare different airlines, departure times and fares all in one place. Tailor the search to your trip, then sort by "Price (lowest to highest)" to see which carrier offers the cheapest DEN to SDY flight.
How many flights per day from Denver Intl. Airport (DEN) to Sidney-Richland Municipal Airport (SDY)?
Direct flights from Denver Intl. Airport (DEN) to Sidney-Richland Municipal Airport (SDY) aren't available daily, so you'll need to take a flight with a layover. Explore your options with Expedia's filters. Enter your travel dates and select either "1 Stop" or "2+ Stops."
What day of the week has the most flights from DEN to SDY?
Friday is usually the busiest day for flights, while Tuesday is often the quietest.* Keep in mind that flight schedules can change based on a number of factors, such as the airline and season.*Busiest/quietest day to travel is based on Expedia flight demand through January to December 2024.
What is the best time to fly from Denver Intl. Airport (DEN) to Sidney-Richland Municipal Airport (SDY)?
To reach Sidney-Richland Municipal Airport (SDY) without delays, select a flight that takes off from Denver Intl. Airport (DEN) before 3 PM. The likelihood of cancellations is 22% higher, on average, for departures after this hour.**Most reliable time of the day and month to travel recommendation is based on January through August 2024 flight status data sourced from OAG's global flight data platform.
What airports do you fly into for Sidney from Denver Intl. Airport (DEN)?
If you're on a direct flight from Denver Intl. Airport (DEN) to Sidney, Basin Intl. Airport (XWA) is the only airport you can land at.
Is it cheaper to buy a plane ticket from Denver Intl. Airport (DEN) to Sidney-Richland Municipal Airport (SDY) last-minute?
Booking your flight from DEN to SDY shortly before your journey is generally more expensive. But if you're flexible with your schedule, you could land a cheap last-minute fare.
Is it cheaper to book a DEN to SDY flight and hotel package?
Compared with arranging flights and hotels separately, booking a DEN to SDY flight and hotel package with Expedia could lead to significant savings. What's more, having it all in one place will take the stress out of travel planning. Just secure your flights and choose from our extensive range of hotels, then tailor your trip with other add-ons like tours, car rentals and activities.
Can I cancel or change the date of my flight from Denver Intl. Airport (DEN) to Sidney-Richland Municipal Airport (SDY)?
In most cases, you can reschedule or cancel your DEN to SDY flight. However, there may be additional charges, especially if you made your booking more than 24 hours ago. Check your itinerary for the airline's policies and fees on flight changes, or if you'd like more details, go to our Customer Service portal.

Travel information

Origin airport
Denver Intl.
Destination airport
Sidney-Richland Municipal
Roundtrip price
$481
Distance
543 mi

Book with confidence

Denver to Sidney Flights

The cheapest times to fly from Denver to Sidney

On average, Thursday can be the cheapest time to fly, according to data from the Airlines Reporting Corporation (ARC), one of the world's biggest databases for global airline sales. The data reveals that you could save up to 16% by flying on a Thursday—the cheapest day to travel on average—instead of a Sunday—the most expensive. Some of the most affordable flights from Denver to Sidney are during the month of March. You can find some of the cheapest flights from Denver to Sidney with Expedia's search tool and vast selection of airlines.

 

The best time to book a flight from Denver to Sidney

Sunday is one of the best days to book for cheap flights from Denver to Sidney: Tickets reserved on a Sunday cost between 6% and 13% less than those reserved on a Friday, according to ARC data. The data also suggests booking early can also lead to cheaper airfares. You could save 24% by buying your tickets for domestic flights at least a month in advance and 10% by booking international flights 2 months in advance.

 

How to find cheap round-trip tickets from Denver to Sidney

Being flexible with your dates and using Expedia's Price Drop Protection and Price Tracking features are some of the best ways of finding a cheap ticket from Denver to Sidney in 2026. You can also book with separate airlines for your outbound and return journeys, from $307 one-way. Expedia also offers Price Drop Protection, so if the cost of your airfare goes down after booking, you'll receive a credit for the difference*. This is available for a small fee, and is free to One Key Gold and Platinum tier members.

 

Expedia's Price Tracking feature means you can stay on top of airfares without manually checking every day. It sends you automated price alerts for cheap Denver to Sidney flights and uses historical data to indicate when the best time to book is. Download Expedia's free app to activate this handy tool in a few easy taps.

 

You could also save big by booking one of Expedia's vacation packages. Bundling together your Denver to Sidney airfare with your accommodations and car rental is often cheaper than booking everything separately. There’s also One Key, Expedia's generous rewards program. Join for free and you could earn One Key cash on most bookings to save on future adventures.

 

*Terms apply.

 

Disclaimer: ARC The statistics are based on average round-trip ticket prices between January and August 2023. The percentages you see are averages.

 

Denver to Sidney Flights

*Flight schedules are subject to change.

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*Available to One Key members.