Moving a departure by a day or a week is the most common change airlines process, and yet it is the change that most often surprises people at the payment screen. The number the airline shows you is not a fee - it is a fare difference, calculated against today's cheapest available seat in your original fare class on the new flight.
The arithmetic of a date change
There are only three inputs to the number.
- Your original ticket's fare bucket (a single letter like Q, T, V, K, etc).
- The cheapest available fare bucket on the new date in the same or lower class.
- The airline's change fee, which for most legacy carriers on non-Basic tickets is $0.
The fare difference is line 2 minus line 1. If line 2 is lower, most airlines will not refund the difference in cash - it becomes a travel credit. Air France and KLM are the two exceptions that regularly refund the difference to the original card.
Cheap-day to expensive-day
Moving from a Tuesday to a Friday, or from a shoulder-season week to a peak week, is where the number can spike. On the same route the peak fare can be triple.
| Route | Tuesday fare | Friday fare | Change delta |
|---|---|---|---|
| Chicago-Denver Feb 3 to Feb 6 | $118 | $268 | +$150 |
| London-Milan Mar 4 to Mar 7 | GBP 88 | GBP 210 | +GBP 122 |
| Los Angeles-Boston Jan 21 to Jan 24 | $219 | $412 | +$193 |
| Sydney-Melbourne Feb 11 to Feb 14 | AUD 149 | AUD 289 | +AUD 140 |
In every case above the change is legal and the airline system will process it, but the fare-difference charge exceeds the value of many original tickets. Before you accept, price the new date as a fresh booking - occasionally a new ticket is cheaper than the change quote if the airline has released more inventory in the new fare bucket for new customers.
Expensive-day to cheap-day
Moving from a Friday to a Tuesday can be free, or even give you a travel credit for the difference.
- Delta, United, American: eCredit for the difference, usually valid one year from the original issue date.
- Southwest: credit is refunded to Travel Funds, valid one year from purchase.
- British Airways: eVoucher for the difference, one year to book.
- Air France / KLM: often refunded to the original card without asking.
- Emirates, Qatar: credit against future travel.
Tools that help
Two habits make date changes cheaper on average.
Use Google Flights Explore. Enter your route and see a whole-month fare grid. This makes the cheap-day vs expensive-day arithmetic visible before you even open the airline's change tool.
Watch for airline waivers. During weather events, staffing issues, or route restructurings, airlines issue blanket waivers that let you move dates freely within a set window. These are announced on the airline's travel advisories page. If a waiver is active on your route, the fare-difference charge is often waived along with the change fee.
For more: how to change your flight without losing money, same-day flight changes, and airline change policies for a side-by-side view of what different carriers charge.
Frequently asked
Can I change the date multiple times?+
Yes on most non-Basic fares. Each change reprices to the current fare on the new date. There is no cumulative penalty for multiple changes.
What if I only want to change the return date on a round-trip?+
That is a standard operation. The airline will reprice the fare, keeping the outbound as-flown and re-pricing the return leg at today's fare on the new date.
Are there specific days that are always cheapest to move to?+
In North America, Tuesday and Wednesday. In Europe, midweek plus Saturday. In Asia, patterns vary more but Tuesday remains a good default.
Marta Reyes
Senior travel editor at AirHelpService
Writes about air travel operations, passenger rights and airport procedures. Reader questions and corrections welcome via our contact page.
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