Glossary entry
Margin
A margin is an amount a provider adds to the wholesale exchange rate before offering it to you. It is often not shown as a separate fee, which makes it easy to overlook: a provider can advertise no commission and still give a rate that costs more than a competitor charging a clear, small fee. You can measure it by comparing the yen you are offered with the amount the reference rate would give, and the shortfall is the cost. See also: spread, foreign transaction fee, and the guide Mid-Market Rate vs the Rate You Actually Get.
A short definition for orientation. The guides and the institutions' own documents are the places for the details.