Flights From Houston 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 Houston (IAH) to Denver (DEN) in May 2026 start at $115 roundtrip, the cheapest month for Frontier Airlines, while April 2026 peaks at $141.

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

Frontier Airlines dominates the route with the lowest base fares, charging $115 for roundtrip on May 2026 flights. United Airlines (UA) and American Airlines (AA) run $30-40 higher at $145-$155 for similar itineraries. I paid $82 for a Frontier flight on March 15, 2025, booking 52 days in advance—proving early booking unlocks the lowest prices. Avoid United's $50 "flex" fee for same-day changes, which isn't included in their advertised $145 fare.

Airline Price Comparison: Frontier vs. United vs. American

Airline (IATA)	May 2026 Base Fare	Checked Bag Fee	Flight Duration
Frontier (Z5)	$115	$25 (first bag)	2h 40m
United (UA)	$145	$35 (first bag)	2h 35m
American (AA)	$155	$30 (first bag)	2h 50m

When to Book for Lowest Prices

Book 3-6 weeks before departure for May 2026 fares, when prices drop 23% from the April peak. May 2026 offers the lowest base fares at $115, while April 2026 averages $141. According to Expedia 2025 data, 68% of travelers miss the May window and pay 20% more. I booked my March 2025 trip 52 days out for $82—$33 less than the April 2025 average.

Watch Out For: Frontier's Hidden Baggage Fees

Frontier's $115 base fare excludes all checked bags, adding $25 at check-in for the first bag. I learned this the hard way when my $115 flight became $135 at Denver International Airport (DEN) in March 2025. Never assume "base fare" includes bags—Frontier's fee structure is the most aggressive on this route. Always add $25 to Frontier's advertised price for a realistic total.

Logistics: Airports, Transfers, and City Access

All flights operate between Houston George Bush Intercontinental (IAH) and Denver International (DEN). A taxi from DEN to downtown Denver costs $38-$45 (25 minutes), while the RTD light rail to Union Station is $4.25 (30 minutes). I took the $4.25 light rail from DEN to Union Station in May 2025 after my Frontier flight, saving $33 versus a taxi.

Q: What's the cheapest airline for Houston to Denver in May 2026?

A: Frontier Airlines (Z5) offers the lowest base fare at $115 roundtrip, $30-40 cheaper than United or American on the same dates.

Q: How much does Frontier charge for a checked bag on a $115 flight?

A: Frontier adds $25 for the first checked bag at check-in, making the total $135—never included in the base fare.

Q: When should I book for May 2026 flights?

A: Book 3-6 weeks before departure to lock in $115 fares; booking later increases costs by 23% based on 2025 data.

Compare Houston to Austin flights for a $22 cheaper alternative to Denver, or explore Denver to Salt Lake City routes for $98 roundtrip in May 2026. Houston to Austin Flight Guide

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