Currency Conversion - Exchange Rates and How to Use Them
Currency conversion is the process of exchanging one country’s currency for another’s. Every international purchase, foreign holiday, or overseas business transaction involves an exchange rate. Knowing how exchange rates work – and how to perform the calculations – protects you from being overcharged and helps you compare deals.
Professional currency exchange is centuries old: money changers at the great medieval trade fairs of Champagne, France, in the 12th and 13th centuries converted coinage between the dozens of different currencies then circulating across Europe, and Italian merchant banking families such as the Medici built vast fortunes in the 14th and 15th centuries partly through bills of exchange that let merchants convert and transfer money between cities without physically transporting gold. The modern system of freely floating exchange rates, where rates change constantly as this page describes, is much younger: it dates only to 1971, when U.S. President Richard Nixon ended the direct convertibility of the US dollar into gold, collapsing the fixed-rate Bretton Woods system that had governed international currency values since 1944.
What Is an Exchange Rate?
An exchange rate states how much of one currency you get for one unit of another.
Example: GBP/USD = 1.27 means 1 British pound buys 1.27 US dollars.
Exchange rates change constantly, driven by trade, investment flows, interest rates, and market confidence.
Converting Between Currencies
To convert from the base currency:
Foreign amount = Home amount × Exchange rate
To convert to the base currency:
Home amount = Foreign amount ÷ Exchange rate
Common Exchange Rate Pairs
| Pair | Reading | Example rate |
|---|---|---|
| GBP / USD | Pounds to US dollars | 1 GBP = 1.27 USD |
| GBP / EUR | Pounds to euros | 1 GBP = 1.16 EUR |
| USD / JPY | Dollars to Japanese yen | 1 USD = 149.50 JPY |
| EUR / GBP | Euros to pounds | 1 EUR = 0.86 GBP |
Buy Rate vs Sell Rate
Banks and bureaux de change use two rates:
Buy rate – the rate at which they buy foreign currency from you (lower). You receive fewer pounds when selling foreign currency.
Sell rate – the rate at which they sell foreign currency to you (higher). You pay more pounds to buy foreign currency.
The difference between the two rates is called the spread – this is the bank’s profit.
Worked Examples
Euros = 500 × 1.16 = 580 EUR.
Pounds = 380 ÷ 1.27 = £299.21.
Buying 600 EUR at sell rate: 600 ÷ 1.20 = £500.00.
Selling 600 EUR at buy rate: 600 ÷ 1.14 = £526.32.
The bureau makes £526.32 − £500.00 = £26.32 on this transaction.
Pounds = 8 500 ÷ 149.50 = £56.86.
At 1.16: 800 × 1.16 = 928 EUR.
At 1.10: 800 × 1.10 = 880 EUR.
The tourist gets 48 fewer euros due to the weaker pound – the holiday costs more in real terms.
Cross Rates
A cross rate converts between two currencies indirectly through a third (usually USD).
Example: To convert EUR to JPY when only EUR/USD and USD/JPY rates are given:
EUR/JPY = EUR/USD × USD/JPY.
If EUR/USD = 1.09 and USD/JPY = 149.50, then EUR/JPY = 1.09 × 149.50 = 162.96.
Factors Affecting Exchange Rates
| Factor | Effect on currency |
|---|---|
| High interest rates | Attracts foreign investment, strengthens currency |
| High inflation | Reduces purchasing power, weakens currency |
| Strong economic growth | Increases demand for currency, strengthens it |
| Political instability | Reduces investor confidence, weakens currency |
| Trade surplus | More demand for exports, strengthens currency |
Key Takeaways
- To convert out: multiply by the exchange rate. To convert back: divide by it.
- The sell rate is always higher than the buy rate – the difference is the bank’s spread.
- Cross rates let you convert between currencies that do not have a direct quote.
- Exchange rates are driven by interest rates, inflation, economic growth, and market sentiment.
Practice: Converting Currencies
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