Q.Distinguish between the nominal exchange rate and the real exchange rate. If you were to decide whether to buy domestic goods or foreign goods, which rate would be more relevant? Explain.

The nominal exchange rate is the rate at which one currency exchanges for another in the foreign exchange market—it tells you how many units of domestic currency you must pay to get one unit of foreign currency (or vice versa). For instance, if $1 = ₹75$, that is the nominal rate.

The real exchange rate, on the other hand, adjusts the nominal rate for price levels in the two countries. It is defined as

where $P_f$ is the foreign price level and $P_d$ is the domestic price level. The real exchange rate measures the relative price of foreign goods in terms of domestic goods—essentially, how much of the domestic good you must give up to buy one unit of the foreign good.

When deciding whether to buy domestic or foreign goods, the real exchange rate is more relevant. The nominal rate alone does not account for differences in purchasing power. Even if the nominal rate makes foreign currency cheaper, foreign goods may still be expensive if their prices (in foreign currency) are high. The real rate captures this: a rise in the real exchange rate means foreign goods have become relatively more expensive (or domestic goods cheaper), discouraging imports and encouraging domestic purchases. Conversely, a fall makes foreign goods relatively cheaper, encouraging imports.

The Nominal Exchange Rate

The nominal exchange rate is the straightforward market rate at which one currency trades for another. If the rupee–dollar rate is ₹80 per dollar, that's the nominal rate. It tells you how many units of domestic currency you need to buy one unit of foreign currency, or vice versa. This is the number you see on currency-exchange boards and in financial news.

Formally, if $e$ denotes the nominal exchange rate (units of domestic currency per unit of foreign currency), then $e = 80$ means ₹80 buys $1.

The nominal rate fluctuates with supply and demand in the foreign-exchange market, driven by trade flows, capital movements, interest-rate differentials, and speculation. But on its own, the nominal rate says nothing about what those currencies can actually buy in their respective economies. A rupee might weaken against the dollar in nominal terms, yet if Indian prices fall relative to U.S. prices, Indian goods could still become cheaper for Americans—and that's where the real exchange rate comes in.

The Real Exchange Rate

The real exchange rate adjusts the nominal rate for the price levels (or inflation) in the two countries. It measures the rate at which the goods of one country trade for the goods of another—essentially, the relative price of a basket of foreign goods in terms of domestic goods.

Think of it this way: suppose the nominal rate is ₹80 per dollar, a representative basket of goods costs $100 in the U.S. ($P^* = 100$), and the same basket costs ₹6,000 in India ($P = 6\,000$). The real exchange rate is

This number tells you that one unit of the Indian basket trades for about 1.33 units of the U.S. basket—Indian goods are relatively cheaper.

If the real exchange rate rises (a real depreciation of the rupee), foreign goods become more expensive relative to domestic goods, encouraging consumers to buy domestically and foreigners to buy Indian exports. If it falls (a real appreciation), domestic goods become relatively pricier, and imports look more attractive.

Which Rate Matters for Your Purchase Decision?

When you're deciding whether to buy a domestic good or import a foreign one, you care about the actual cost in terms of purchasing power, not just the currency conversion. The real exchange rate is the relevant metric because it incorporates both the nominal rate and the relative price levels.

Imagine you're choosing between an Indian-made laptop priced at ₹60,000 and an imported U.S. laptop priced at $800. At a nominal rate of ₹80 per dollar, the U.S. laptop costs ₹64,000 in rupee terms—seemingly more expensive. But if U.S. goods are generally cheaper (lower $P^*$ relative to $P$), the real exchange rate might reveal that, after adjusting for quality and the overall price environment, the foreign laptop offers better value. Conversely, if Indian prices are low and the real rate favors domestic goods, the ₹60,000 laptop is the better deal even if the nominal rate looks unfavorable.

In short, the nominal rate tells you the currency conversion; the real rate tells you the economic trade-off. Firms deciding where to source inputs, consumers comparing import prices to domestic alternatives, and policymakers assessing competitiveness all look at the real exchange rate because it reflects relative costs and purchasing power.