Exchange Rates: The Price of One Currency in Another

What this means

Currency is bought and sold, and like anything bought and sold it has a price. That price is the exchange rateThe price of one country's currency expressed in units of another country's currency.. If you can buy one euro for a certain number of dollars, that number is the price of a euro in dollars, in exactly the same sense that a price tag states the price of a jacket in dollars.

Exchange rates are quoted in two directions, and mixing them up is the single most common source of error in this entire topic. Dollars per euro and euros per dollar are reciprocals of each other. Before you calculate anything, say out loud which currency is being priced and which is doing the pricing. A quote of 150 yen per dollar and a quote of 0.0067 dollars per yen describe the same market; one is priced in yen and one is priced in dollars.

The foreign exchange marketThe worldwide market in which currencies are bought and sold, operating continuously across time zones. is where this price is set. For most major currencies it is set the ordinary way, by supply and demand, with no authority announcing the number.

Demand for a currency comes from anyone who needs it. Importers buying goods priced in that currency, tourists planning a trip, investors purchasing assets denominated in it, and firms paying wages or suppliers there all must acquire it first. Supply comes from the mirror image: holders of that currency who want something priced in another. When more people want to hold a currency relative to how much is offered, its price rises. When fewer do, its price falls.

Two terms name those movements. A currency appreciatesRising in value against another currency, meaning it now buys more of that other currency than before. when its price in terms of another currency rises, and depreciatesFalling in value against another currency, meaning it now buys less of that other currency than before. when that price falls. These are always statements about a pair. A currency cannot appreciate in the abstract; it appreciates against something.

Not every currency floats freely. Some governments fix or manage their exchange rate rather than letting the market set it, which is why the standard says supply and demand determine the rate for most major currencies rather than for all of them. The supply-and-demand model still explains the pressures such a currency is under; it simply does not get the last word on the observed number.

Why it matters

Any time you compare a price in one country to a price in another, the exchange rate is doing silent work. A shirt marked 30 in London and a shirt marked 3000 in Tokyo cannot be compared until both are expressed in the same unit, and the number that makes that conversion possible is a market price that changed while you were reading this sentence.

This is not only a tourist's concern. It determines whether an imported laptop is affordable, whether a family sending money to relatives abroad can send enough, whether a company's overseas revenue is worth more or less when brought home, and whether a domestic manufacturer can compete with a foreign one. The exchange rate sits underneath a very large number of ordinary decisions.

Try it

1. Set up the comparison. You will price a comparable shirt in the United Kingdom, Japan, and South Africa. Define "comparable" before you start, specifying material, style, and roughly equivalent quality, so you are not comparing a designer shirt in one country to a basic one in another.
2. Find local prices. Using retailer websites in each country, record the price of your chosen shirt in British pounds, Japanese yen, and South African rand. Record the retailer, the exact item, and the date. Note whether the listed price includes that country's sales or value-added tax, since including it in one country and excluding it in another will corrupt your comparison.
3. Look up current exchange rates for all three currencies against the U.S. dollar from a source you can cite, and record the date and time you retrieved them. Rates move continuously, so all three must be captured at roughly the same moment.
4. Write each rate in both directions before converting. For each currency, state the rate as dollars per unit and as units per dollar, and confirm the two are reciprocals. This step exists to prevent the direction error and should not be skipped.
5. Convert all three prices into U.S. dollars. Show the full arithmetic for each conversion, including which form of the rate you used and why. Then sanity-check every result: if a shirt converts to a number that seems implausible for a shirt, you have almost certainly multiplied where you should have divided.
6. Rank the three shirts by U.S. dollar price and identify the cheapest and most expensive. Then write a short analysis of what could explain the gap, considering local labor and rent costs, taxes, tariffs on imported clothing, shipping distance, and differences in typical local incomes.
7. Test the sensitivity. Suppose the dollar appreciates by ten percent against all three currencies. Recompute the dollar prices of all three shirts and state precisely what happened to how expensive foreign goods are for a U.S. buyer. Then do the same for a ten percent depreciation.
8. Reverse the perspective. Take one U.S.-priced item, convert it into each of the three local currencies, and answer the question a shopper in each of those countries would ask: is the U.S. item cheap or expensive from where they stand? Explain why the answer can differ across the three countries even though the U.S. price never changed.

Check yourself