What’s on this page? Calculating the interest rate in three ways.

Calculate the interest rate from the loan amount, the amount of the fixed annuity, X monthly annuity, and the number of annuities. We use this when we forget at what interest rate we took out the loan, whether we want to check if our annuity was calculated correctly, or when the annuity increases due to revaluation … The interest rate is calculated using linear and compound methods.

The price of money is defined by the time we borrowed the money (or we lent it to someone) and the amount. We borrowed 1000 units, returned 1000 in 10 days, and added 10 units for the prize. We’re thinking, but we’ve given a high enough reward, but too little. The calculation shows that this award represented 43.79% interest on an annual basis. We were able to borrow different amounts several times and we also returned different amounts several times. In the end, we returned everything, even with interest. If we have up to 15 such data, we use Calculate interest rates for up to 15 events.

If we have more than 15 data, we prepare the data in a CSV file and use the Calculate the interest rate from a CSV file. A CSV file is a text file where data is separated by a separator. An example can be found in the calculation.

Important: the interest rate is calculated according to the compound method.

On the next page is a classic amortization schedule. What is special is the preparation of data in the form of a CSV file. If you have a situation where most of your information is the same as your amortization schedule, some additions are needed. Data can be found at the end of the amortization schedule. Click on the data, press ctrl / a (specify all), then ctrl / c (copy). Use Notepad to open a new document and press ctrl / v (paste). Correct the data according to your needs and save it. Go to the interest rate calculation from the CSV file. Attach the file and perform the calculation.

There are two more sides to calculating interest. To calculate interest using the compound method, go to compound interest calculation and for linear calculation, go to simple interest calculation.

If you encounter any problems, please email me at info@r4m.biz.

The calculation for loans with a fixed annuity
Loan Amount
The amount of the annuity
X monthly annuity (usually 1)
Number of annuities

R4M presents the annual discount rate that equates the sum of the present values of all amounts received from the loan relationship with the sum of the present values of all amounts, i.e. instalments and interest or annuities, commissions, protected …), which have been paid with this respect. Discounting is performed in a compound method. To calculate R4M you need interest rate calculator.

With Interest rate calculator you can solve the most simple to the most complex cases.

You will all agree that the price of money is defined by the time and the amount of getting the money and the time and the amount of the paying back money. The same is when being in role of a lender, investor or saver. Performance is subject to time and the amount of borrowing the money and the time and the amount of getting back the money lent.

How to fix the rate for money, which will contain everything?

The method is given by the following equation

mnumber of cash flows paid by the lender
jsequence number for the cash flows paid by the lender (draw down)
ajcash flow (drawdown) in period j
ntotal number of cash flows paid by the borrower
ksequence number of the cash flows paid by the borrower (repayment)
bkcash flow (repayment) of period k
tj and tkinterval, expressed in fractions of a year between the date of the first cash flow and the date of cash flow or k.
In the case of a loan, amounts of received loans are on the left side of the equation and the amount of any repayment of principal, interest and costs on the right side. In the case of investments, the amount of the investment is on the left side of the equation and the value of investments and the income thereon on the right.

Calculate interest rates for up to 15 events If you have up to 15 data, use this calculation.

(If your browser does not support HTML5 date field, enter the date in the form yyyy-mm-dd)

#DateEnter the date of the event.PaymentsEnter the amount of the loan or investment.RepaymentsEnter the amount of your refund or state investment.DescriptionOptional: Enter a description of the event.


Calculate the interest rate from a CSV file
CSV file format
  • Date
  • Payments – decimal point is point (.)
  • Repayments – decimal point is point (.)
  • Description (optional)

For example

Load CSV file

Date format