Denver to Phoenix Flights
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Independent European travel research. Verified data, updated for 2026
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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Flavia Voican
Travel entrepreneur & founder of 360 Business Tour. Writing about flights, destinations, and travel hacks since 2011.
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