Interest Rate Parity Calculator
Calculate currency forward prices using covered and uncovered interest rate parity formulas with spot rates, interest rate differentials, and forward points for forex arbitrage analysis.
About This Calculator
The Interest Rate Parity (IRP) Calculator helps forex traders, investors, and finance professionals determine theoretical currency forward prices using the covered and uncovered interest rate parity theories. Understanding IRP is essential for identifying arbitrage opportunities, hedging foreign currency exposure, and pricing forward contracts in international markets.
The covered interest rate parity formula — Forward Rate = Spot Rate × (1 + rprice) / (1 + rbase) — assumes a no-arbitrage condition where the forward rate eliminates the possibility of risk-free profits. Each interest rate is adjusted for the contract period using the 360-day market convention: r = annual rate × (days / 360). The uncovered parity formula — Forward Rate = Spot Rate × (1 + (rprice − rbase)) — provides an alternative estimate based solely on the interest rate differential.
Regional Notes
- India (IN): RBI regulates forex markets. The rupee (INR) forward market uses USD/INR as the most liquid pair. Forward contracts up to 12 months are common for corporate hedging.
- United States (US): The Fed influences USD interest rates. Major pairs include EUR/USD, GBP/USD, and USD/JPY. Forward contracts are actively traded OTC with standardized maturities.
- United Kingdom (UK): BoE sets GBP interest rates. GBP/USD and EUR/GBP are key pairs. The 360-day convention is standard for most currency pairs except GBP which sometimes uses 365-day convention.
Frequently Asked Questions
What is interest rate parity?
Interest rate parity (IRP) is a theory that states the difference between interest rates of two countries equals the difference between the spot exchange rate and the forward exchange rate of their currencies. It prevents arbitrage opportunities in foreign exchange markets.
What is the difference between covered and uncovered interest rate parity?
Covered interest rate parity uses a forward contract to hedge against exchange rate risk, making the calculation arbitrage-free. Uncovered interest rate parity does not use a forward contract and relies on expected future spot rates based on interest rate differentials alone.
How is the forward rate calculated using covered interest rate parity?
The covered interest rate parity formula is: Forward Rate = Spot Rate × (1 + Price Currency Interest Rate) / (1 + Base Currency Interest Rate), where each interest rate is adjusted for the contract period using a 360-day year convention.
What does a forward premium or discount mean?
A forward premium occurs when the forward rate is higher than the spot rate, indicating the base currency has a higher interest rate. A forward discount occurs when the forward rate is lower than the spot rate, meaning the price currency has a higher interest rate.
Why is the 360-day convention used in interest rate parity calculations?
The 360-day convention is standard in foreign exchange markets, particularly for money market instruments. It simplifies calculations and aligns with market practice where most short-term interest rates are quoted on a 360-day basis.
Does interest rate parity hold in real markets?
Interest rate parity generally holds in efficient markets with free capital flow, but deviations can occur due to transaction costs, capital controls, political risk, and market imperfections. During financial crises, IRP deviations tend to be larger and more persistent.
What is the difference between buying and selling a currency forward?
Buying a currency forward (taking a long position) means agreeing to purchase the base currency at a predetermined rate on a future date. Selling a currency forward (taking a short position) means agreeing to sell the base currency at a predetermined rate on a future date.