Prepared by A-J | Author brand: 盡職生活｜阿J的普通人理財筆記
About the author/site · Vocus @WUCJ ↗ · Editorial policy
Page version: 2026-08-16 | Official or primary sources are preferred for material rules and figures. AI may assist structure, translation, and code, but is not used as the sole factual source.
About the author/site · Vocus @WUCJ ↗ · Editorial policy
Page version: 2026-08-16 | Official or primary sources are preferred for material rules and figures. AI may assist structure, translation, and code, but is not used as the sole factual source.
Key distinction: Market FX, a bank's posted rate, and your executable transaction rate can differ.
Buying foreign currency uses the higher bank-sell side
You pay the bank's selling price when acquiring foreign currency.
Converting back uses the lower bank-buy side
Selling the currency back typically receives the bank-buy rate.
The gap is an important conversion cost
The wider the spread, the larger the favorable market move needed to break even.
Frequent small conversions can compound costs
Small spreads repeated many times can become meaningful over time.
Primary / official sources
Posted rates change continuously. Actual transactions use the rate and fees shown by the executing bank, broker, or payment provider.