Calculate Real Exchange Rate from Nominal

Real Exchange Rate Calculator

Calculate the inflation-adjusted exchange rate between two currencies.

Calculated Real Exchange Rate:

This indicates the relative purchasing power of the domestic currency abroad.

function calculateRER() { // 1. Get input values var nominalRateInput = document.getElementById("nominalRate").value; var domesticCPIInput = document.getElementById("domesticCPI").value; var foreignCPIInput = document.getElementById("foreignCPI").value; // 2. Parse inputs to floats var E = parseFloat(nominalRateInput); var Pd = parseFloat(domesticCPIInput); var Pf = parseFloat(foreignCPIInput); // 3. Validation if (isNaN(E) || isNaN(Pd) || isNaN(Pf) || E < 0 || Pd < 0 || Pf < 0) { alert("Please enter valid positive numbers for all fields."); return; } if (Pf === 0) { alert("Foreign Price Level cannot be zero."); return; } // 4. Calculation: RER = E * (Pd / Pf) // Where E is foreign currency units per domestic unit. var rer = E * (Pd / Pf); // 5. Display Result var resultDiv = document.getElementById("rerResult"); var outputSpan = document.getElementById("rerOutputValue"); outputSpan.innerHTML = rer.toFixed(4); resultDiv.style.display = "block"; }

Understanding the Real Exchange Rate

While the nominal exchange rate tells you how much foreign currency you can get for your domestic currency at a bank or currency exchange, it doesn't tell the whole story about purchasing power. It doesn't account for the differences in the cost of living (inflation) between two countries.

The Real Exchange Rate (RER) adjusts the nominal rate to reflect the true relative purchasing power of one currency against another. It measures how many times more (or less) goods and services foreign currency buys compared to domestic currency, adjusted for price levels in both countries.

The Formula Used

This calculator uses the standard macroeconomic definition of the real exchange rate:

RER = Nominal Rate × (Domestic Price Level / Foreign Price Level)

Where:

• Nominal Rate (E): Define this as "units of Foreign currency per 1 unit of Domestic currency".
• Domestic Price Level (P_d): Usually represented by a Consumer Price Index (CPI) or GDP deflator for the domestic economy.
• Foreign Price Level (P_f): The comparable price index for the foreign economy.

Example Calculation

Let's define the US Dollar ($) as the domestic currency and the Euro (€) as the foreign currency.

• Nominal Rate: $1 buys €0.85 (E = 0.85).
• Domestic Price Level (USA CPI): 120 (P_d = 120).
• Foreign Price Level (Eurozone CPI): 110 (P_f = 110).

Plugging these into the calculator:

RER = 0.85 × (120 / 110)
RER = 0.85 × 1.0909…
RER ≈ 0.9273

Interpreting the Results

The result helps economists determine economic competitiveness:

• If RER equals the Nominal Rate: Purchasing Power Parity holds; price levels are relatively equal.
• If RER rises (an appreciation): Domestic goods are becoming relatively more expensive than foreign goods. This can hurt exports as they become pricier for foreigners to buy, but it makes imports cheaper for domestic consumers.
• If RER falls (a depreciation): Domestic goods are becoming relatively cheaper. This can boost competitiveness in export markets, but makes importing foreign goods more expensive.

Use this calculator to monitor how inflation differentials are affecting the true value of your currency on the global stage.