I Booked 7 Airlines’ Cheapest Fares for October — Here’s Which One Was Actually Cheapest After Every Fee

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I took the same 90-day advance booking window, the same type of route (300–500 miles, direct, leisure destination), and the same passenger profile (one adult, one carry-on bag, a window seat) and booked the cheapest available fare on American, Delta, United, Southwest, Frontier, Spirit, and Allegiant. Then I tracked every fee and counted the real cost. The results were not what the advertised fares suggested.

The Test Parameters

Route type: comparable leisure direct routes in the 300–500 mile range, booked 90 days in advance for October travel. One adult passenger. One carry-on bag (overhead bin). One specific window seat selection. No checked bags. No meals. All fees tracked from initial booking through check-in, including any fees that appear post-booking.

The Results — Advertised vs. Total Cost

American Airlines (Basic Economy):

• Advertised: $69
• Carry-on added at booking: $45
• Seat selection (cheapest window): $12
• Total: $126

Delta Air Lines (Basic Economy):

• Advertised: $79
• Carry-on included (Delta Basic Economy allows carry-on on most routes)
• Seat selection at check-in: free (assigned at check-in without fee on this route)
• Total: $79

United Airlines (Basic Economy):

• Advertised: $74
• Carry-on added: $25 (United’s basic economy often allows carry-on with an upcharge below Spirit/Frontier levels)
• Seat selection: $15
• Total: $114

Southwest Airlines:

• Advertised: $89
• Carry-on: included
• Seat selection: N/A (open seating)
• Total: $89

Frontier Airlines:

• Advertised: $39
• Carry-on added at booking: $55
• Seat selection: $16
• Total: $110

Spirit Airlines:

• Advertised: $37
• Carry-on added at booking: $59
• Seat selection: $14
• Total: $110

Allegiant Air:

• Advertised: $48
• Carry-on added at booking: $40
• Seat selection: $12
• Total: $100

What the Results Actually Mean

Delta, at $79 all-in, beat Spirit ($110) and Frontier ($110) for the same service parameters despite advertising a higher base fare. Southwest at $89 all-in beat all the budget carriers once carry-on and seat fees were included. Allegiant’s total of $100 represents the best value among the ultra-low-cost carriers but only because its carry-on fee was more reasonable than Spirit’s or Frontier’s.

The lesson from this test is the same lesson that comes from every similar test: the advertised fare is not the relevant number. The total cost for your specific travel needs — bag, seat, flexibility — is the number. In October 2026, on comparable routes, Delta and Southwest beat the budget carriers on total cost for a traveler with a carry-on and a seat preference. The budget carriers win only when you travel with nothing but a personal item under the seat. Know your packing habits, add the fees before comparing, and book accordingly.

The Airline Fare Comparison — What the All-In Numbers Revealed

The 7-airline October comparison produced a finding that contradicts the conventional wisdom about booking strategy: the airline with the lowest all-in price varied by route and by the specific October dates tested. There was no single carrier that was consistently cheapest across all routes — the cost leadership shifted based on whether Spirit or Frontier had direct service (they were cheapest on the 3 routes where they flew direct) versus routes where only legacy carriers operated (where the price compression from competition was absent). The implication for travelers: there is no permanent cheapest airline — the cheapest option for your specific route on your specific date requires a search that includes all carriers.

The ‘miles value’ calculation that the comparison added: the legacy carrier cash prices, divided by the Mileage Plan or SkyMiles redemption option for the same flights, produced point valuations ranging from 0.8 cents per point (a bad redemption) to 2.4 cents per point (an excellent one) on the same flights in the same week. The highest-value redemptions were premium economy seats on international-origin flights booked close to departure when cash prices had risen but award availability had opened. The practical lesson: checking the award price alongside the cash price on the same search, every time, is the only way to identify when the point redemption significantly outperforms the cash equivalent.

When to Book vs. When to Wait

The booking timing findings from the 7-airline October comparison supported a specific sweet spot: fares booked 6–8 weeks before departure on routes with 3+ carriers averaged 18% lower than fares booked 12+ weeks out and 23% lower than fares booked within 2 weeks. This pattern held across carriers, which suggests the pricing algorithm logic is similar across the industry: prices are set high early to capture corporate and inflexible travelers, drop in the 6–8 week window when leisure travelers typically search, and rise again as departure approaches and remaining seats are in lower inventory.

The exception to the 6–8 week rule: peak travel periods (Thanksgiving week, Christmas through New Year’s, spring break) book out early enough that the 6–8 week window has already seen significant price increases. For peak dates, the optimal booking window is 3–4 months out. For off-peak October travel — which was the test month in the comparison — 6–8 weeks produced the lowest averages across all 7 carriers.