What is compound interest?
Compound interest is a fascinating financial concept that can significantly impact your savings.
Compound interest is the process by which interest on money or other interest-bearing assets accrues at a faster rate than the original principal. In financial theory, compound interest is the rate of return on an investment or savings plan or the amount of interest that accumulates or compounds over time.
The concept is also known as accrual accounting.
The compound interest rate is determined by how often the compounding process takes place. The money can be compounded daily, monthly, quarterly, or annually, which will affect your investment’s growth over time.
The number of compounding periods makes a significant difference when calculating compound interest.
The more frequently compound interest is calculated, the faster it accumulates. However, if you’re being charged interest, monthly or yearly compounding will save you money compared to daily compounding.
How compound interest works
Compound interest is the interest you earn on the interest you already made. For example, if you put $1 in a savings account, you earn interest on that $1. If you put $100 in the savings account, you make interest on that $100. If you put $1,000 in the savings account, you earn interest on that $1,000.
Compound interest is calculated by multiplying the initial principal amount by one plus the annual interest rate raised to the number of compound periods minus one.
The total initial amount of the loan is then subtracted from the resulting value.
Compound interest allows investments to work in your favor. The earlier you start saving money, the better. But the longer you take to pay off your compound interest debts, the higher they will become.
Additionally, it’s crucial to be mindful of how compound interest can work against you if not managed properly.
On the whole, compound interest works in favor of borrowers. That being said, it’s important to pay down debt as quickly as possible so that you don’t get stuck with high-interest rates.
Compound interest example
Compound interest accelerates your gains even if you make no further deposits:
- Year One: A $100 initial deposit generates 5% interest, or $5, boosting your total to $105 in year one.
- Year Two: Your $105 yields 5% interest, or $5.25 each year. You currently have a balance of $110.25.
- Year Three: Your $110.25 balance receives 5% interest, or $5.51. Your account balance increases to $115.76.
This is an illustration of annual compounded interest. Many institutions, notably online banks, compound interest daily and credit your account monthly, expediting the process even more.
Compounding, of course, plays against you and in favor of your borrower when you borrow money. You must pay interest on borrowed funds, and if you do not pay your debt in full the next month, you will owe interest on the amount borrowed plus any accumulated interest.
Compound interest formula
Compound interest can be calculated in various ways, and self-education may provide invaluable insight into achieving your financial objectives while maintaining reasonable expectations. When performing computations, consider a few “what-if” scenarios using alternative projections to determine what might happen if you saved a little more or earned interest for a few more years.
Certain individuals prefer to examine the data more closely by conducting the computations themselves. You may either use a finance calculator with formula storage functions or a standard calculator with an exponent key.
Calculate compound interest using the following formula:
A = P (1 + [r / n]) ^ nt
To use this calculation, insert variables:
A: The total amount you’ll receive.
P: The initial deposit, sometimes referred to as the principle.
r: the yearly percentage rate of interest, expressed in decimal form.
n: the annual number of compounding periods (for example, monthly is 12, and weekly is 52).
t: the time period (measured in years) during which your money compounds.
Example math
You have $1,000 invested at a rate of 5% compounded monthly.
How much money will you have in fifteen years?
A = P (1 + [ r / n ]) ^ nt
A = 1000 (1 + [.05 / 12]) ^ (12 * 15)
A = 1000 (1.0041666…) ^ (180)
A = 1000 (2.113703)
A = 2113.70
After fifteen years, you’d have around $2,114. Due to rounding, your final total may vary somewhat. $1,000 is your original deposit, and the remainder $1,114 is interest.
Spreadsheets do the math for you
Spreadsheets can do the entire calculation for you. Generally, you’ll use a future value computation to determine your total balance after compounding.
Microsoft Excel, Google Sheets, and other software packages support this feature, although the values will need to be somewhat adjusted.
Using the above example, you can calculate the future value using Excel’s future value function:
=FV(rate,nper,pmt,pv,type)
Each of your variables should be entered in an individual cell. For instance, Cell A1 may include the number “1000” representing your original deposit, while Cell B1 may contain the number “15” to signify 15 years.
Compound interest vs. simple interest
Compound interest is a type of interest that is earned on the initial principal amount and also on the accumulated interest of previous periods. In contrast, simple interest is only calculated on the initial principal amount.
This means that compound interest will generate a more significant return over time than simple interest. You can use compound interest in various types of loans, such as student loans, mortgages and installment loans.
When you’re looking to buy a significant appliance, such as a refrigerator or television, the salesperson might ask you if you want to finance the purchase. If you do, they’ll offer you two types of interest rates: simple interest and compound interest.
Which one is better for you? It depends on how long you take to pay off the loan. With compound interest, your payments are applied not just to the principal (the amount you borrowed) but also to any accrued interest. This means that the total amount you owe will grow over time.
With simple interest, your payments are applied only to the principal, so you’ll pay less in total interest, but it will take longer to pay off the loan.
How compound interest can work against you
While compounding interest may be suitable for saving, investing, and wealth development, it’s critical to remember that it might work against you if you’re paying off debt. Indeed, compounding is one factor that contributes to the lethal nature of having an outstanding credit card amount.
Supposing you hold a $10,000 debt on a credit card (we’ll pretend the interest rate is the low 4% compounded daily, despite the reality that credit card APRs are typically much higher). You intend to use the card exclusively and pay it off in five years. Even though you’d be reducing your balance and paying an exceptionally low-interest rate, you may wind up paying a significant amount in interest – more than $1,000.
And if the interest rate is compounded every day at 18 percent — which is closer to the typical credit card interest rate — you would pay $5,236 in interest after five years.
How to benefit the most by using the compound interest
Compound interest is best used by saving and investing.
Selecting an interest-bearing savings account — such as high-yield savings accounts, money market accounts, or certificate of deposit — is one approach to make compound interest work to your advantage. When selecting an account, seek one with the lowest fees and the best annual percentage yield (APY), the interest income on a 12-month deposit.
It’s important to note that even the most exemplary savings accounts provide interest rates that barely surpass inflation, making them ideal for short-term investments. If you’re looking to generate long-term wealth, whether it’s for retirement or a long-term goal, investing your money will truly put it to work for you.
Savings products typically give interest rates ranging from 0.01 percent to 3%, depending on the status of the economy, whereas the historical average rate of return on the stock market is 10% before inflation is included.
When you create an investment account, such as a 401(k), an IRA, a brokerage account, or a mutual fund, you get the opportunity of automatically reinvesting any dividends or interest earned on your assets. As a result, your returns will increase.
Takeaway
Compound interest is powerful and can be helpful or destructive to your wallet, depending on the situation. Make sure you understand how interest compounds before making any decisions.
