How the planner finds it
- Long-haul legs only, and at most two of them, because that is where the gap is big enough to survive a card fee.
- Each is re-quoted as if bought from the foreign end's country, in that country's currency, through the same live search with a point-of-sale override.
- The result is converted to dollars with European Central Bank reference rates fetched fresh and cached for a day.
- It is only reported when the foreign quote is at least 3% and at least $10 cheaper.
- The card does the arithmetic you would otherwise forget, naming what a 3% foreign-transaction fee would eat out of the saving.
Worked example
Dallas → Milan, re-quoted from Italy in euros
example output- US point of sale
- $514 per person
- Italian point of sale
- €442 ≈ $514
- Difference after conversion
- $0
- Shown on the plan?
- No
Drawn as the zero, because zero is the common result: both long-haul legs come back identical once converted and nothing is shown. This is the check that catches the routes where the gap is 15%, and that tells you when it is nothing rather than implying it is not.
When it does not work
- Card foreign-transaction fees and dynamic currency conversion at checkout can erase a small saving entirely. Pay in the local currency, with a card that has no FX fee.
- Some airlines require a billing address in the point-of-sale country. Online travel agents usually do not.
- Exchange rates move between quoting and paying.
- Only long-haul legs are checked, at most two per plan, because each check costs a live search.
Risk
Low risk
Buying from another country's site is ordinary commerce, not a trick against the airline. The exposure is FX fees and a possible billing-address wall.