Interest Parity Calculator

Measure currency parity with market rates and periods. View implied forwards, deviations, and annualized comparisons. Export clean results for analysis, review, and reporting needs.

Calculator Form

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Example Data Table

Case Spot Forward Domestic % Foreign % Days Basis Implied Forward
Covered parity sample 1.1000 1.1120 5.00 3.00 180 360 1.110837
Short tenor sample 0.9200 0.9245 4.25 2.10 90 360 0.924838
Longer tenor sample 149.5000 151.0000 2.40 0.50 270 360 151.617761

Formula Used

Covered interest parity links spot, forward, and interest rates.

Simple compounding: Forward = Spot × (1 + domestic rate × time) ÷ (1 + foreign rate × time)

Continuous compounding: Forward = Spot × e(domestic rate − foreign rate) × time

Time equals days to maturity divided by the chosen day count basis.

Parity gap equals actual forward minus implied forward.

Gap percent equals parity gap divided by implied forward.

How to Use This Calculator

  1. Select the required calculation mode.
  2. Enter the spot rate and time to maturity.
  3. Enter domestic and foreign annual interest rates.
  4. Add the market forward rate when checking gaps or implied rates.
  5. Choose simple or continuous compounding.
  6. Set the day count basis and notional amount.
  7. Click the calculate button to show results above the form.
  8. Use the CSV or PDF buttons to export the result table.

About Interest Parity

What this calculator does

Interest parity connects exchange rates and interest rates. It helps traders, analysts, and finance students test whether currency pricing stays aligned. This calculator gives quick results for covered and uncovered parity checks. It also estimates missing rates when market data is incomplete.

Why parity matters

When covered interest parity holds, two investment paths should give the same domestic outcome. One path keeps money at home. The other converts into foreign currency, earns foreign interest, and locks a forward contract. If the values differ, the market may show a pricing gap.

What you can measure

You can calculate the implied forward exchange rate from spot and interest rates. You can also solve for an implied domestic rate or implied foreign rate. The parity gap mode compares the actual forward rate with the theoretical forward rate. That makes mispricing easier to see.

How uncovered parity is shown

Uncovered interest parity does not use a locked forward contract. It compares rate differentials with an expected future spot rate. This tool shows the theoretical estimate and the deviation from your expected future rate. That makes expectation analysis more practical.

Why day count and compounding matter

Short periods can create small but important differences. The chosen day count basis changes the time fraction. The compounding method changes the growth factors. Both settings affect the implied forward result. This matters in treasury work, hedging reviews, and academic exercises.

How exports help

The export options help you save a clean record of your calculation. Use CSV for analysis in sheets. Use PDF for reports, class notes, or client files. The example table also gives sample values for testing inputs before using live market figures.

FAQs

1. What is covered interest parity?

Covered interest parity is the relation between spot rate, forward rate, domestic interest rate, and foreign interest rate. It assumes exchange risk is hedged with a forward contract.

2. What is uncovered interest parity?

Uncovered interest parity compares interest rate differences with an expected future spot rate. It does not lock a forward contract, so expectations drive the comparison.

3. Why can a parity gap appear?

A gap can appear from market frictions, bid ask spreads, timing differences, credit costs, capital controls, or input errors. Small gaps may not be tradable.

4. Which rate is domestic?

The domestic rate belongs to the currency used in the quoted spot price numerator outcome. Keep your rate and quotation convention consistent through the full calculation.

5. Why is the notional amount included?

The notional shows how the pricing difference affects a specific investment size. It helps translate theoretical gaps into a money value for analysis.

6. Should I use simple or continuous compounding?

Use the convention that matches your market, course, or internal model. Money market examples often use simple rates. Some valuation models use continuous rates.

7. Can this tool solve for missing interest rates?

Yes. It can calculate an implied domestic rate or an implied foreign rate when you already know the spot, forward, tenor, and the other rate.

8. Is this calculator useful for real trading decisions?

It is useful for screening and education. Real execution also needs transaction costs, spreads, taxes, funding terms, and settlement details before action.

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.