How do differences in real interest rates drive capital flows and exchange rates?
Topic 6.6 Real Interest Rates and International Capital Flows: explain how differences in real interest rates between countries drive international capital flows, exchange rates, and net exports.
A focused answer to AP Macroeconomics Topic 6.6, covering how relative real interest rates drive international capital flows, how those flows change the exchange rate and net exports, and how this links the loanable funds market, the foreign exchange market, and the AD-AS model, with a worked chained question.
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What this topic is asking
Topic 6.6 closes Unit 6 and the whole course by tying the financial sector to the open economy: how differences in real interest rates drive international capital flows, and how those flows move exchange rates and net exports. The College Board wants you to chain the loanable funds market, the foreign exchange market, and the AD-AS model, the most integrated reasoning on the exam.
Real interest rates and capital flows
From capital flows to the exchange rate and net exports
Capital flows move the foreign exchange market, which then moves net exports:
The link to the loanable funds market
Capital flows also connect to the loanable funds market:
Try this
Q1. Which way does financial capital flow when a country's relative real interest rate rises? [1 point]
- Cue. Into the country (a net capital inflow), to earn the higher return.
Q2. A capital inflow appreciates the currency. What happens to net exports? [1 point]
- Cue. Net exports fall (exports dearer, imports cheaper).
Exam-style practice questions
Practice questions written in the style of College Board exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
AP 2019 (style)1 marksMultiple choice. If real interest rates in a country fall relative to the rest of the world, the most likely sequence of effects is (A) capital inflows, currency appreciation, net exports fall. (B) capital outflows, currency depreciation, net exports rise. (C) capital inflows, currency depreciation, net exports rise. (D) capital outflows, currency appreciation, net exports fall. (E) no change in capital flows.Show worked answer →
The answer is (B). Lower relative real interest rates make domestic assets less attractive, so financial capital flows out to chase higher returns abroad. Capital outflows mean residents supply more domestic currency (to buy foreign assets), so the currency depreciates, which raises net exports.
(A) describes a rise in relative rates. (C) and (D) mix up the directions. (E) ignores the capital-flow response. Lower relative rates cause outflows, depreciation, and higher net exports, so (B).
AP 2022 (style)6 marksFree response. A country's central bank raises real interest rates above those abroad. (a) Explain the effect on international capital flows. (b) Draw a correctly labelled foreign exchange market graph for the domestic currency and show the effect of the capital flows. (c) State whether the currency appreciates or depreciates. (d) Explain the effect on net exports. (e) On an AD-AS graph, show the effect of the change in net exports. (f) Explain how this international channel relates to the loanable funds market.Show worked answer →
A 6-point chained FRQ.
(a) Capital flows (1 point): higher relative real interest rates attract foreign financial capital, so there is a net capital inflow.
(b) Forex graph (1 point): exchange rate on the vertical axis, quantity of the domestic currency on the horizontal axis; the inflow raises demand for the domestic currency, shift demand right.
(c) Result (1 point): the currency appreciates.
(d) Net exports (1 point): a stronger currency makes exports dearer and imports cheaper, so net exports fall.
(e) AD-AS (1 point): lower net exports shift aggregate demand left, lowering output and the price level (relative to what they would have been).
(f) Loanable funds link (1 point): the capital inflow adds to the supply of loanable funds, which moderates the domestic real interest rate, so capital flows connect the loanable funds market and the foreign exchange market.
Markers reward the capital inflow, the rightward currency demand shift, the appreciation, the fall in net exports, and the loanable-funds link.
Related dot points
- Topic 6.4 Effect of Changes in Policies and Economic Conditions on the Foreign Exchange Market: identify the determinants that shift currency supply and demand, including interest rates, income, prices, and tastes.
A focused answer to AP Macroeconomics Topic 6.4, covering the determinants that shift currency supply and demand in the foreign exchange market, including relative interest rates, relative income, relative price levels, tastes, and speculation, and how monetary policy moves exchange rates, with a worked graphing question.
- Topic 6.3 The Foreign Exchange Market: draw the foreign exchange market for a currency, explain the supply of and demand for it, and find the equilibrium exchange rate.
A focused answer to AP Macroeconomics Topic 6.3, covering the supply of and demand for a currency in the foreign exchange market, the equilibrium exchange rate, what each curve represents, and how to read appreciation and depreciation off the graph, with a worked graphing question.
- Topic 6.5 Changes in the Foreign Exchange Market and Net Exports: explain how appreciation and depreciation change net exports, and trace the effect on aggregate demand.
A focused answer to AP Macroeconomics Topic 6.5, covering how currency appreciation and depreciation change exports and imports, the effect on net exports, and how this feeds through the foreign exchange market into aggregate demand and the AD-AS model, with a worked chained question.
- Topic 4.7 The Loanable Funds Market: draw the loanable funds market, explain the supply of saving and demand for borrowing, and show how shifts determine the real interest rate.
A focused answer to AP Macroeconomics Topic 4.7, covering the loanable funds market, the supply of saving and demand for borrowing, the real interest rate, the determinants that shift each curve, and the contrast with the money market, with a worked graphing question.
- Topic 5.5 Crowding Out: explain how government deficit borrowing raises the real interest rate and reduces private investment, using the loanable funds market.
A focused answer to AP Macroeconomics Topic 5.5, covering the crowding-out effect, how government deficit borrowing raises the real interest rate and reduces private investment in the loanable funds market, the long-run growth consequences, and the contrast with monetary policy, with a worked graphing question.
Sources & how we know this
- AP Macroeconomics Course and Exam Description — College Board (2023)