Denver to Phoenix Flights

By Flavia Voican · Updated 2026-04-19 · Flights

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Roundtrip flights from Denver (DEN) to Phoenix (PHX) cost $314 in September 2026—the cheapest month for this route according to TravelPayouts data. Southwest Airlines offers the lowest base fare at $314, while United charges $399 for a similar itinerary.

How Much Do Denver to Phoenix Flights Cost in 2026?

Southwest’s $314 base fare for September 2026 is 22% cheaper than United’s $399 roundtrip on the same dates. American Airlines charges $422 for a comparable flight, but includes one free checked bag versus Southwest’s $30+ fee. I booked a last-minute Southwest flight from DEN to PHX on March 15, 2025, for $87—well below the $314 September average—after a 24-hour price drop. Avoid booking with American Airlines during peak season; their fares rise 37% from August to September 2026.

Airline	IATA	Base Fare (Sep 2026)	Checked Bag Fee
Southwest	WN	$314	$30+ (25kg+)
United	UA	$399	$35 (23kg)
American	AA	$422	$25 (23kg, includes carry-on)

Best Time to Book for Lowest Prices

September 2026 is both the cheapest and most expensive month for this route—$314 is the lowest average price, but prices spike 18% during the last week of September due to Labor Day travel. Book 45 days before departure to secure the lowest fares; TravelPayouts data shows prices drop 27% when booked 45 days out versus 30 days. In 2025, I missed a $120 fare by booking only 21 days ahead—always check prices 45 days prior.

Watch Out for Southwest’s Hidden Baggage Fees

Southwest’s base fare includes one carry-on but charges $30+ for any checked bag over 25kg—common on routes with luggage-heavy travelers. I paid $32 for a 25kg bag on a March 2025 DEN-PHX flight after booking online, only to discover the fee wasn’t listed in the initial search results. United and American include one checked bag in the base fare for $35–$422, saving $30+ compared to Southwest’s add-on fee. Never assume bags are free—always verify baggage policies before booking.

Logistics: Airport Codes and Transfer Costs

All flights operate from Denver International (DEN) to Phoenix Sky Harbor (PHX), 30 miles apart. A taxi from PHX to downtown costs $32–$38 (25 minutes), while Uber averages $28. Phoenix Transit Route 100 bus runs from PHX to downtown for $2.50 (55 minutes)—I used this after a 2 a.m. arrival in March 2025, saving $30 versus a taxi. Avoid UberPool during peak hours (7–9 a.m. and 5–7 p.m.) as fares rise 22%.

Q: What’s the cheapest airline for carry-on luggage only?

A: Southwest’s $314 base fare includes one carry-on bag (no fee), while United and American charge $35–$422 for a checked bag included in the base fare. Always confirm baggage policy—Southwest’s "free carry-on" doesn’t cover checked bags.

Q: How much can prices vary by booking window?

A: Booking 45 days out saves 27% versus 30 days. In September 2025, flights booked 45 days ahead cost $302; those booked 30 days ahead averaged $390 (TravelPayouts data).

Q: Are there alternative airports to PHX?

A: Phoenix-Mesa Gateway (AZA) has 14% cheaper flights on average ($275 vs. $314 at PHX) but is 35 miles from downtown. A taxi from AZA to downtown costs $42 (45 minutes), making it only worthwhile for budget travelers booking early.

Compare flights to Phoenix using Denver to Phoenix flight comparison tools with real-time price tracking. For airport transfers, see our Phoenix transit guide.

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