How to Compute Monthly Interest on a Loan?

How to Compute Monthly Interest on a Loan?

The Precarious Situation

Calculating interest on a monthly basis is a necessary skill. Interest rates are frequently expressed as an annual percentage—either an annual percentage yield (APY) or an annual percentage rate (APR)—but knowing how much that translates to in dollars and cents is useful. We are accustomed to thinking in terms of monthly expenses.

You may have monthly electricity payments, food prices, or a car payment, for example. Interest is also calculated on a monthly (if not daily) basis, and those repeating interest calculations build up to significant amounts over the course of a year. Converting from an annual rate (APY or APR) to a monthly interest rate is the same whether you’re paying interest on a loan or collecting interest in a savings account.

 An Example of a Monthly Interest Rate Calculation

Divide the yearly rate by 12 to get a monthly rate that reflects the 12 months in a year. To finish these procedures, you’ll need to convert from percentage to decimal format.

Assume your annual percentage yield (APY) is 10%. What is your monthly interest rate, and how much would you pay or earn on $2,000 if you were to borrow it?

Divide the annual rate of inflation by 100 to get a decimal: 10/100 = 0.10.

To get the monthly interest rate in decimal notation, divide that value by 12: 0.0083 = 0.10/12

Multiply $2,000 by the total amount of money to find the monthly interest: 0.0083 multiplied by $2,000 equals $16.60 every month.

Divide the decimal monthly rate by 100 to get the percentage: 0.0083 x 100 = 0.83 percent

Your interest rate is 0.83 percent per month

Interest can be calculated for months, days, years, or any other time period. The rate you use in calculations, regardless of the term, is known as the periodic interest rate. Typically, rates are quoted in terms of an annual rate, so you’ll need to convert to whatever periodic rate corresponds to your query or financial product. 

You may use the same notion of the interest rate calculation for other time periods as well:

Divide the annual rate by 360 to get a daily interest rate (or 365, depending on your bank).

Divide the annual rate by four to get a quarterly rate.

Divide the annual rate by 52 to get a weekly rate.


Your loan balance changes every month with several loans. For example, you gradually pay down your debt on auto, home, and personal loans over time, and you usually end up with a reduced balance each month.

This is known as amortization, and an amortization table can assist you in calculating (and visualizing) how much interest you pay each month.

Your monthly interest costs drop over time, while the amount paid toward your loan debt rises.

 Credit Cards and Home Lending

Home loans might be difficult to understand. It’s a good idea to use an amortization plan to figure out your interest charges, but you may need to do some further research to determine your real rate. To understand how your principal payment, interest charges, taxes, and insurance add up to your monthly mortgage payment, visit our mortgage calculator (below).

 You may be aware of your mortgage’s annual percentage rate (APR) but bear in mind that APR might include costs other than interest (such as closing costs). APRs on adjustable-rate mortgages can also change. 

 You can add new charges and pay off debt on credit cards at any point during the month. All of this activity complicates calculations, but it’s still important to understand how your monthly interest adds up. In many circumstances, an average daily balance (the sum of each day’s balance divided by the number of days in each month) can be used (and the finance charge is calculated using the average daily balance). In some situations, your card issuer will charge interest on a daily basis (in which case you should calculate a daily interest rate rather than a monthly one). 

 Interest Rates and Annual Percentage Yield

In your computations, make sure to utilize the interest rate rather than the annual percentage yield.

Compounding interest, which you earn as your account grows owing to interest payments, is accounted for by the APY. Unless your interest is compounded annually, your APY will be higher than your actual rate, so APY can give you an erroneous result. On the other hand, APY makes calculating how much you’ll earn annually on a savings account with no additions or withdrawals a breeze. 

Frequently Asked Questions (FAQs)

What is a good credit card interest rate?

In February 2022, the average credit card interest rate was 16.17 percent.

For retail credit cards, you should anticipate having to pay a few more points. Credit cards for businesses and students can help you reduce your interest rate.

 What is the prime rate of interest?

Banks charge their most valuable customers the prime interest rate. To put it another way, it’s the best rate available on any particular day. Institutional customers are usually the only ones that may get this rate. The ordinary customer pays the prime rate plus an additional rate based on their credit risk.

 How do you lower the interest rate on your credit card?

Interest rates on credit cards may be negotiated, but it is up to the card issuer to do so. If you have strong credit habits, such as making on-time monthly payments, a card issuer is more likely to offer you a cheaper rate.

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