Price What Cancelling Would Cost Before You Book — Free
The flexible fare looks like the expensive option until the day you need to move the trip — then the change fee plus the fare difference makes the cheap ticket the costly one. Put both prices and the change fee into the same receipt and the comparison stops being a feeling; the difference is a number you can decide against.
The proof surface
Free path: the card computes locally in the browser with no key and no account. Where an AI step helps, any free chat assistant works — Google AI Studio's free tier and Groq's free tier were both no-card and rate-limited when this page was reviewed on 2026-09-13 (limits change; check before you rely on them).
Why the flat version breaks
Booking screens show two prices and no decision. What matters is the third number nobody displays: the fee you pay when plans change, multiplied by the chance they will. The receipt makes that number visible next to the fare you were comparing it with.
How to run the comparison in four passes
Fares move. Comparing a quote from Tuesday with one from Friday tells you about the airline's pricing, not about the risk you are insuring against.
The fee appears in the fare conditions, often per change and per sector. Four travellers on a connecting route can turn a 95 fee into a 380 one, which is exactly the number that changes the decision.
If you always pay for a bag, the flexible fare's included bag is worth real money and belongs in the comparison. If you travel with hand luggage, it is worth nothing and should be zero.
The card gives you the gap. The airline's own fare rules decide what a change really costs — take a screenshot of them at the moment of booking, because conditions are what you will be arguing from later.
SAMPLE DATA, NOT A VERIFIED CLAIM: LIS → BRS · 12 Feb 2027 · flexible 412 · restricted 168 · change fee 95 · bag 38. Replace these values with your own source before you rely on anything.
What breaks first
Leaving the change fee at zero
A restricted fare with no change fee is a flexible fare with a different name. Enter the published fee or the comparison silently becomes a comparison of the two headline prices.
Comparing a refundable fare with a refundable-plus-extras booking
Seat, bag and insurance bundles sit outside the fare conditions. If you add them to one side and not the other, you are no longer comparing like with like.
Reading the difference as a guarantee
The card compares the numbers you typed. It cannot price a schedule change, a route cancellation or a medical emergency clause — those live in the conditions, and some of them pay out regardless of the fare you bought.
What you pay otherwise
| The usual route | What it leaves out | Cost |
|---|---|---|
| Changing a restricted fare late | Fare difference plus the fee, both decided on the day | the fee, at the worst time |
| Abandoning the trip | The whole restricted fare, with taxes possibly refundable | the full ticket value |
| Buying travel insurance in a rush | A policy taken after booking rarely covers the reason you need it | a policy that will not pay |
| This page + the free perforated fare ticket | Computed in your tab, result on screen before you type anything | $0 |
Try the free perforated fare ticket
A Lisbon fare comparison is already priced with the change fee included and the difference stated. Set the change fee to 240 and the ranking flips in the ticket.
Open the free perforated fare ticket →Keep the work if you will use it again
Both fares, the fee, the extras and the difference, plus the stub figure, with no account.
Both fares, the fee and the difference stay free. The one-time tier adds the printable ticket with the decision figure on the stub plus the saved comparisons behind it.
Boundary: This compares fares you type in; it is not financial or insurance advice, and it does not interpret the airline's conditions. Read the fare rules and any insurance policy wording for the journey you are actually buying.