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Interest Rate Calculator

Loan interest rate

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Investment interest rate

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Simple interest rate

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Find out what interest rate you're receiving on your credit card, loan, mortgage, savings or investment using this interest rate calculator.


Disclaimer: Whilst every effort has been made in building this tool, we are not to be held liable for any damages or monetary losses arising out of or in connection with the use of it. Full disclaimer. This tool is here purely as a service to you, please use it at your own risk.

What is my interest rate?

Use our interest rate calculator to work out the interest rate you're receiving on credit cards, loans, mortgages or savings. An interest rate is a percentage that is charged by a lender to a borrower for an amount of money. This translates as a cost of borrowing. You may be borrowing the money from someone (loan) or lending it to them (savings or investment).

If you wish to calculate interest amounts received on your savings, use the savings calculator for compound interest or simple interest calculator for simple interest. To calculate the interest payments on a loan, use the loan calculator.

What interest rate am I getting on my loan?

Calculating the interest rate you're receiving on your credit card or loan requires a series of calculations involving your loan amount, number of payments made and either the monthly payment or interest paid. Our calculator uses the Newton-Raphson method to calculate the interest rates on loans. This is a complex process resulting in a more accurate interest rate figure. The Newton-Raphson method chooses a series of values to try, and then converges on the answer once the equation balances.

Whether you've taken out a mortgage or loan, it can be difficult to decipher the interest rate you're paying on it. That's where our calculator steps in, giving you a clear indication of what you may be paying. Note that our interest rate calculator uses monthly compounding.

If you'd like to use a spreadsheet to calcuate your interest, give this simple loan calculator spreadsheet from Vertex42 a try.

What interest rate am I receiving on my investment/savings?

To calculate the rate of return on an investment or savings balance we use an adapted version of the compound interest formula used in the compound interest calculator. We enter into the formula your current balance, original principal amount, number of compounds per year and time period.

Should wish to work out the rate of interest you might receive on an investment based upon a current value and future value, give the CAGR calculator a try. For assistance calculating returns on investments, try the IRR calculator

What is the nominal interest rate?

Nominal interest rate is the interest rate figure before an adjustment for inflation is taken into account. The formula for nominal interest rate is:

Nominal interest rate = n × ( (1 + r)1/n - 1)

r = effective interest rate
n = number of compounding periods

What is the effective interest rate?

The effective annual rate is the interest rate earned on a loan or investment over a time period, with compounding factored in. It can also be referred to as the annual equivalent rate (AER). To give an example, a 5% annual interest rate with monthly compounding would result in an effective annual rate of 5.12%. This is because monthly interest is effectively accrued on top of previous monthly interest. The more times interest is compounded within the time period, the higher the effective annual rate will be.

Effective interest rate = (1 + (i/n) )n - 1

i = nominal interest rate
n = number of periods

To learn more about the types of interest rates referenced in the calculator, read our article about the differences between nominal, effective and APR interest rates.


Note: The interest rate calculator is provided for information purposes only. Please speak to an independent financial advisor for any kind of advice on loans.