IB Economics: Exchange Rates FAQ

Exchange rates form a subtopic of International Economics in the IB Economics guide, covering how currencies are priced, why they move, and who gains or loses. Both SL and HL students learn demand/supply diagrams and policy effects; HL students also calculate rates and revenue changes. It's examined on Paper 1, Paper 2 and, for HL, Paper 3.

A floating rate is set purely by market demand and supply, with no central bank intervention. A fixed rate is pegged to another currency or to gold and defended through constant central bank buying and selling. A managed float sits between the two — mostly market-driven, with occasional intervention to smooth swings.

Exchange rates are compulsory for both SL and HL IB Economics students. The core diagrams, definitions and the Marshall-Lerner condition apply to everyone. HL students carry extra depth: numerical calculations of exchange rate changes and their effect on export and import revenue, assessed specifically on Paper 3.

The Marshall-Lerner condition states that a currency depreciation improves a country's trade balance only if the sum of the price elasticities of demand for exports and imports is greater than 1. If demand is inelastic, depreciation can actually worsen the trade balance in the short run — which is what the J-curve describes.

The J-curve shows a country's current account balance initially worsening after a currency depreciation, before eventually improving — because contracts, habits and supply chains take time to adjust to new relative prices. Plotted over time, the balance dips first, tracing the downward stroke of a J, then rises once quantities catch up.

Write the rate as currency A per unit of currency B, decide whether the question wants you to multiply or divide, and always sense-check the direction: if a currency weakens, buying foreign goods should cost more, not less. HL Paper 3 questions almost always follow this same three-step logic.

The most common error is mislabelling the axes — students draw quantity against price of currency but forget to state which currency's price sits on the vertical axis. Examiners also dock marks when a shift arrow isn't tied to a stated cause, such as a change in interest rates or export demand.

A strong essay names the exchange rate system in question, draws a fully labelled diagram showing the relevant shift, and explains the transmission mechanism step by step before evaluating with a real-world example plus a counter-argument, such as time lags or the Marshall-Lerner condition. Structure earns marks as much as content does.

Recent papers have asked students to evaluate how currency depreciation affects a country's trade balance, discuss why central banks intervene to manage their exchange rate, and compare the trade-offs of fixed versus floating systems for a named economy. Expect a dated, real-world context in almost every question.

Exchange rates appear on Paper 1 (extended response, all levels), Paper 2 (data response using real statistics, all levels), and Paper 3 (HL only, quantitative and case-study questions requiring calculations). SL students are never asked to calculate exchange rate changes numerically — that's an HL-only skill.

Yes — HL students calculate export and import values before and after a rate change and interpret these alongside the Marshall-Lerner condition on Paper 3. SL students cover the same theory and diagrams but are only assessed on written analysis and evaluation, never on numerical exchange rate calculations.

Exchange rates connect directly to trade protection, the balance of payments and trade agreements, all housed under the same International Economics unit. A depreciation acts a bit like an informal tariff — making imports pricier without any government policy — so examiners often ask you to compare the two mechanisms directly.

Exchange rates make popular Internal Assessment and Extended Essay topics because they're constantly in the news — a central bank rate decision, a currency crisis, a trade dispute — giving students real, dated articles to analyse. The risk is picking a topic too broad to cover properly within the IA's 800-word commentary limit.

Exchange rates rank among the trickier International Economics topics because they combine diagrams, real-world policy and — at HL — arithmetic, all in one question. Students who struggle usually haven't drilled enough past-paper data-response questions; those who practise the calculations early tend to find it becomes one of their stronger topics by the mocks.

The most effective revision combines clear notes explaining the diagrams and the Marshall-Lerner condition, topic-specific worksheets that drill HL exchange rate calculations, and full timed mock papers closer to exams. Past papers from the IB store and a teacher's specimen questions are useful too, but targeted practice on the calculation type matters most.