How to Calculate an Exchange Rate's Effect on Prices

Multiply a foreign price by the exchange rate to convert it, then compare before and after to see what a stronger or weaker currency does to that price.

The Exchange Rate Price Effect formula

Price in the other currency = original price × exchange rate (quoted as the other currency per 1 unit of the starting currency)
To convert the other way, divide by that rate, which is the same as multiplying by its reciprocal (1 ÷ rate)
Appreciation or depreciation % = (new rate − old rate) ÷ old rate × 100, using the rate quoted per 1 unit of the currency you are tracking

Calculator

See what a change in the yen-per-dollar rate does to the dollar price of an import and the yen price of an export.

Import price in yen

The Japanese seller's price, which does not change.

Export price in dollars

The American seller's price, which does not change.

Old rate (yen per dollar)

New rate (yen per dollar)

Import price after

$300

Yen price divided by the new yen-per-dollar rate.

Import price before: $330
Export price after (yen): 2,200,000
Export price before (yen): 2,000,000
Dollar appreciation: 10%

How to calculate Exchange Rate Price Effect, step by step

1
Write down which currency the rate is quoted per unit of. A rate of 100 yen per dollar means one dollar buys 100 yen. The same pair can also be quoted as dollars per yen, the reciprocal: 1 ÷ 100 = 0.01 dollars per yen.
2
Convert the price using the matching side of the rate. To turn a yen price into dollars, divide by the yen-per-dollar rate. To turn a dollar price into yen, multiply by that same rate.
3
Recompute after the rate changes. Run the same conversion with the new rate, holding the foreign-currency price fixed, so the only thing that moved is the exchange rate itself.
4
Compare the two converted prices. A rise in the converted price of an import means the home currency weakened against it. A fall means the home currency strengthened. The same logic prices out what an export now costs a foreign buyer.

Worked example: Exchange Rate Price Effect

Suppose the rate moves from 100 yen per dollar to 110 yen per dollar, a stronger dollar. A Japanese camera priced at 33,000 yen costs Americans 33,000 ÷ 100 = 330 dollars before the move and 33,000 ÷ 110 = 300 dollars after, a cheaper import. An American export priced at 20,000 dollars costs Japanese buyers 20,000 × 100 = 2,000,000 yen before the move and 20,000 × 110 = 2,200,000 yen after, a pricier export that can cost the seller sales.

Reading the same rate from either side

Every exchange rate can be quoted in two directions, and mixing them up is the most common source of a wrong answer. A quote of 100 yen per dollar and a quote of 0.01 dollars per yen describe the exact same market price, one is simply the reciprocal of the other: 1 ÷ 100 = 0.01, and 1 ÷ 0.01 = 100.

The fix is mechanical rather than conceptual. Before converting anything, write the rate as units of the currency you want per one unit of the currency you are giving up, flipping the quoted number if it is not already in that form. Multiply the amount you hold by that rate, and the units cancel correctly. Skip that step and it is easy to multiply where you should have divided, which is off by a factor of the rate squared rather than just wrong by a little.

Why the two percentages never match

When a rate moves from 100 to 110 yen per dollar, it is tempting to say the yen fell by the same 10 percent that the dollar rose. It did not. The dollar's move is measured against its own old value, 100, while the yen's move has to be measured against the yen's own old value in dollars, 1 ÷ 100 = 0.01.

The yen's new value is 1 ÷ 110 ≈ 0.00909 dollars. Its percent change is (0.00909 − 0.01) ÷ 0.01 × 100 ≈ −9.1 percent. So a 10 percent dollar appreciation is a smaller 9.1 percent yen depreciation, not a matching 10 percent fall. The gap grows with the size of the move, so on a free-response question that asks for both currencies' percentage change, recompute each one from its own starting value rather than assuming the numbers mirror each other.

Carrying the price effect into net exports

The two converted prices in the worked example are the mechanism behind a line that shows up across the AP Macro curriculum: a stronger currency tends to lower net exports, and a weaker currency tends to raise them.

When the dollar strengthens, every foreign good priced in its own currency converts into fewer dollars, which is why American buyers see cheaper imports and tend to buy more of them. At the same time, every American good priced in dollars converts into more units of the foreign currency, so foreign buyers see pricier exports and tend to buy fewer. Imports up and exports down both point the same way: net exports (exports minus imports) fall, which pulls on aggregate demand. A weaker dollar runs the same chain in reverse.

Exchange Rate Price Effect questions

Do you multiply or divide by the exchange rate?

Multiply when the rate is quoted as the currency you want per one unit of the currency you are converting from, and divide when it is quoted the other way. A rate of 100 yen per dollar converts dollars to yen by multiplying and converts yen to dollars by dividing.

How do you calculate the percent appreciation or depreciation of a currency?

Percent change = (new rate − old rate) ÷ old rate × 100, with the rate quoted per one unit of the currency you are tracking. A move from 100 to 110 yen per dollar is a 10 percent dollar appreciation; the yen's own percentage, worked out from the reciprocal, is a smaller fall of about 9.1 percent, since each currency's percentage divides by its own starting value.

Why does a stronger dollar hurt American exporters?

A stronger dollar means foreign buyers need more of their own currency to buy the same dollar-priced good, so the good gets more expensive to them even though its dollar price never changed. That price increase in the buyer's currency is what can push export sales down.

Why does a stronger dollar help American shoppers buying imports?

The foreign price of the imported good has not changed, but each dollar now converts into more of the foreign currency, so the same foreign price translates into fewer dollars. That is why economists tie a stronger dollar to cheaper imports and a weaker dollar to more expensive ones.

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Last updated September 5, 2026

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