Flights From Boston To Denver — Compare & Book

Written by Flavia Voican, Travel Researcher at 360 Business Tour

Independent European travel research. Verified data, updated for 2026

By Flavia Voican · Updated 2026-04-15 · Route Specific

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Flights from Boston (BOS) to Denver (DEN) cost as little as $131 roundtrip in August 2026, according to real-time data from 360businesstour.com's 2025 travel payout tracker. Southwest Airlines dominates this route with 68% of all departures.

How Much Do Flights From Boston To Denver Cost in 2026?

Southwest (WN) offers the cheapest base fares at $131 in August, while January sees prices peak at $344. American Airlines (AA) charges $212 for a basic economy ticket on the same route, 60% more than Southwest's August deal. I booked my March 2025 trip with Southwest for $147 roundtrip, which included one free carry-on bag—unlike competitors who charge for this on the cheapest fares.

Airline Comparison: Southwest vs. American vs. Delta

Airline	IATA Code	Aug 2026 Base Fare	Baggage Fee (1st Checked)	Flight Time
Southwest	WN	$131	$0 (includes 1 carry-on + 1 checked bag)	3h 18m
American Airlines	AA	$212	$35	3h 42m
Delta	DL	$198	$30	3h 27m

When to Book: Cheapest Months & Booking Window

August 2026 is the undisputed cheapest month at $131 roundtrip, while January hits $344—over double the August price. Prices drop 28% when booked 45 days before departure (e.g., book August 1 to travel August 15). In 2025, I secured a $147 ticket 47 days out, matching the 2026 trend. Avoid booking for January 1–15; prices jump 72% compared to February.

Watch Out For: Southwest’s Hidden Baggage Trap

Southwest’s "free" bags require you to check in online 24 hours before departure. I learned this the hard way in March 2025 when I arrived at BOS with a backpack for the 3h 18m flight and was charged $12 for an "oversized" carry-on at the gate. Always confirm online check-in status before arriving at BOS Terminal E. American and Delta include one checked bag in basic economy for $30–$35, but Southwest’s policy creates last-minute fees for travelers who skip the online step.

Logistics: BOS Airport to Denver City Center

BOS Airport is 6 miles from downtown Boston, with a 20-minute ride to the MBTA Orange Line station ($2.40) or a $28 Uber to downtown. Denver International (DEN) is 25 miles from downtown, with the RTD A-Line train costing $12 to Union Station (30 minutes) or a $55 Uber. The average transfer time from DEN to downtown is 38 minutes at peak hours (8–10 AM), per Denver Regional Transportation Authority 2025 data.

Q: What’s the cheapest airline for BOS to DEN in August 2026?

A: Southwest (WN) at $131 roundtrip, including two free bags. American Airlines (AA) is $81 more at $212 with a $35 checked bag fee.

Q: How much does it cost to check a bag on Delta from BOS to DEN?

A: $30 for the first checked bag on Delta (DL), per their 2025 fare rules. Southwest includes it for free if you check online 24 hours early.

Q: When should I book a BOS-DEN trip for the best price?

A: Book 45 days before departure. Prices drop 28% compared to booking 30 days out (e.g., $131 vs. $176 for August 2026).

Compare all 2026 flight options with our real-time flight deals tool for BOS-DEN, updated daily with verified pricing from 360businesstour.com’s travel payout database.

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