Kathy Jane Buchanan
Written by Kathy Jane Buchanan

Kathy Jane Buchanan has more than 10 years of experience as an editor and writer. She currently worked as a full-time personal finance writer for PaydayChampion and has contributed work to a range of publications expert on loans. Kathy graduated in 2000 from Iowa State University with degree BSc in Finance.

What is Fixed Interest, and How Does it Work?

Fixed interest is an investment product that pays a predetermined interest amount or rates each year on the initial principal invested. The interest rate, known as the coupon rate, remains at a pre-agreed level for a set period. Governments, corporations, or banks issue fixed-income instruments. It involves lending money directly, buying bonds, or investing in debt instruments like debentures.

Fixed-interest rate loans provide stability, consistency, and safety for the borrower. The main feature of fixed-interest rate loans is that the interest rate does not change over time, which means that regardless of market fluctuations, borrowers always know exactly how much the liabilities are. Knowing the liabilities helps to budget more easily because borrowers already know the monthly repayment. Other features include fixed loan terms so that the borrower’s repayment is divided into a fixed number of termly payments and the option to make lump sum payments if needed.

Fixed-interest investments provide an important portfolio management tool since it is relatively simple to measure the risk-return relationship of a fixed-interest investment. The fixed interest offers investors a more predictable return on the invested capital and, in some cases, an annual income. Fixed-interest products are often used as a hedge against inflation which tends to be less volatile than stocks or other financial instruments, and the returns are often tied to the inflation rate. Fixed-interest investments protect against fluctuations in currency markets. The formula for fixed interest is P × (1 + i)n, where P represents the principal, i is the interest rate per period, and n is the number of periods.

Main Points

  • Fixed-interest type of loans provides stability and predictability for borrowers. A fixed interest rate is an interest rate that stays the same throughout the life of a loan. 
  •  Fixed-interest loans include mortgages, home equity, and auto loans. Many financial institutions also offer equity loan options with fixed interest rates to ensure borrowers have a stable and predictable repayment plan. One common example of fixed-interest loans is the fixed-rate mortgage loan.

What is a Fixed Interest Rate?

A fixed interest rate is an interest rate that stays the same for the duration of a loan, such as a mortgage or a car loan which means that the monthly payments remain the same throughout the life of the loan. Fixed interest type of loan provides stability and predictability since borrowers know how much is needed to pay each month regardless of future market rates.

The history and origin of fixed interest rates are traced back to the 16th century when it became a common practice among merchants to lend money to businesses or individuals who would then agree to pay back a fixed amount plus interest. The British Parliament passed the Bank of England Charter, which allowed the Bank of England to set an interest rate for loans and deposits and lend money to the government.

By the mid-19th century, fixed exchange rates began to be adopted worldwide as banks sought stability in transactions and investments. In subsequent years, other countries established rates fixed against a base currency such as gold, silver, or interbank lending. By the 20th century, legislative acts had been introduced that allowed governments to set minimum pooling systems whereby all lenders charged a minimum agreed-upon interest rate, which helped to ensure fair competition between financial institutions and protect borrowers from predatory lending practices.

How Fixed Interest Rate Work?

A fixed interest rate locks in an interest rate that stays the same over a loan’s term, regardless of changes to market conditions or the lender’s prime rate. Fixed rates are often used on mortgages, cars, and student loans. The interest rate for such loans usually comes higher than variable-rate loan options. Still, it helps borrowers budget for the monthly payments because the borrower is aware of the liabilities from the start.

What Are the Other Terms for Fixed Interest?

Other terms for fixed interest include bond, loan balance, charge, annuity, and certificate of deposit. Fixed interest is interest that remains the same during the life of the investment and does not vary with inflation or other economic realities. Fixed-interest investments typically offer a lower rate than variable-rate securities. Bond, loan, charge, annuity, and certificate of deposit are other terms that describe fixed interest. They all involve an agreement between a lender and a borrower in which the lender receives a set amount of money at regular intervals over a specified time.

What Is an Example of a Fixed Interest Rate?

One example of a fixed interest rate is a 10-year loan with a 6.5% interest rate, meaning the borrower pays 6.5% compounded annually for ten years unless the rates change. Another example of a fixed interest rate is a loan or savings account with an interest rate that stays the same throughout the life of the investment. Fixed interest rate investments are usually safer, providing consistent and predictable returns. Fixed interest rates are lower than variable rates but are higher if inflation is expected to increase over time.

What Types of Loans Use Fixed Interest Rates?

Listed below are the types of loans that used fixed interest rates.

  • Fixed-rate mortgages. Fixed-rate mortgages are the most common type of loan in which the interest rate stays the same throughout the loan term, typically 15–30 years. Payments remain the same monthly regardless of market interest rate fluctuations, making it easier to manage financial planning.
  •  Home equity loans. Home equity loans are a popular way to tap into existing home equity for renovations or other expenses. The interest rate for home equity loans remains fixed over the life of the loan and is paid off either in one lump sum or through regular payments, depending on the agreement with the lender.
  •  Auto loans. Most auto loans offer fixed-rate options, where interest rates remain constant throughout repayment. Fixed-rate options are beneficial if the borrower has a longer loan duration and rates fall in future years—the borrower won’t worry about rising and increasing the monthly payment.
  •  Personal loans. Many personal loan lenders offer fixed-rate personal loans at competitive rates. Other lenders charge variable or adjustable-interest rates, which depend on external factors like Federal Reserve Rates.
  •  Business loans. Fixed business finance products allow companies to access funds as needed on an ongoing basis, from short-term overdrafts to long-term financings such as asset finance or venture debt — all these structures are increasingly offered on fixed terms that act as a barrier against any increases in external factors such as inflation or vendor prices increases.
  •  Student Loans. Fixed student loan interest rates, remain set from beginning to end, providing debtors with the assurance that payments won’t increase over time no matter what happens with economic conditions.
  •  Unsecured Loans. Unsecured fixed-rate products exist that remain locked in until completely paid off despite regular potential fluctuations in macroeconomic conditions. Unsecured fixed-rate personal loans have high APRs, but fees are added onto due upfront by most lenders who prefer to lock up individuals’ assets via collateral such as a car using a secured loan product rather than providing unsecured funding.
  •  Personal loans. A personal loan is an unsecured loan offered by banks and other financial institutions. Generally, these loans are provided to individuals who need funds for various reasons, including home renovation, unexpected medical bills, or debt consolidation. Borrowers receive the funds quickly in one lump sum and then repay the loan in monthly installments over some time with interest when applying for a personal loan. Fixed interest is used in personal loans to give the borrower a predictable interest rate every month for the duration of the loan, meaning that the monthly payments for a fixed-rate loan remain stable and the same each month if other economic factors cause market interest rates to fluctuate. Borrowers invest in long-term stability and responsibility when paying a loan with fixed-rate interest.
  •  Auto Loans. An auto loan is used to purchase a vehicle. Credit history and capacity to repay the loan determine whether or not a borrower is authorized for the amount required. Lenders offer auto loans in-person at dealerships and online, with terms and durations typically ranging from 36 to 72 months. Fixed interest is typically used in auto loans because lenders want to set an interest rate that remains the same throughout a loan, giving borrowers some certainty on the monthly payments and total loan cost. In addition, fixed interest rates help protect borrowers from volatile markets, which increases the interest rate during the lifetime of a loan.
  •  Federal Student Loan. A federal student loan is a government-backed loan offered by the U.S. Department of Education to help students with college-related expenses such as tuition, fees, books, allowances, and other educational-related expenses. Federal student loans often include more flexible payback terms and lower fixed interest rates than private student loans. Fixed interest rates are utilized for federal student loans because they provide the borrower stability by ensuring that the loan payback amount remains constant, facilitating the calculation and budgeting of loan payments over the loan term. Congress annually establishes a fixed interest rate for federal student loans that do not change with market pressures.

What is the Formula for Fixed Interest Rate?

The formula for fixed interest is P × (1 + i)n, where (P) represents the principal, (i) is the rate of interest per period, and n is the number of periods. The interest rate is the percentage of money charged for borrowing, expressed as a decimal. The principal is the original amount of money borrowed, and time refers to the period over which interest is charged.

YearFixed InterestAmount
Suppose a borrower would like to know the exact monthly payment, the principal amount, and other details of the repayment agreement. The year in fixed interest calculation refers to a loan’s annual percentage rate (APR) for a certain period. For example, the APR for a mortgage loan is seven percent per annum.In fixed interest calculation, the term “fixed interest” refers to an interest rate that remains constant across the life of a loan or investment instrument. In other words, calculations based on a set interest rate calculate the constant proportion of the total amount paid as interest each period during the duration of a loan or investment package.The amount in the fixed interest calculation is the total amount that must be repaid after a loan period, taking into account the loan’s interest rate and the principal borrowed. The sum is greater than the interest rate. The set amount must be accounted for when calculating the cost of a loan to assess whether it is affordable.

How to Calculate Fixed Interest?

To calculate fixed interest, first, find the principal amount. The principal amount is the initial amount borrowed by a borrower. Second, determine the period. The period is how long a loan takes to repay and is usually expressed in years or months based on the agreement with a lender. Third, calculate the interest rate. The interest rate must be stated in the loan agreement and found online or by contacting lenders for the current rates for fixed-rate home equity loans. It’s important to note that an additional 3-4% is added if a borrower takes out an unsecured loan for additional risk factors to lenders since it’s not backed by collateral or assets. Fourth, identify payment frequency. Loan payments typically come due every month, but depending upon the lender and the agreement made, some debts are repaid on a weekly schedule; when calculating interest annually with fixed-rate loans and mortgages then; divide the number by 12 (for monthly) or 52 (for weekly).

How Much Can a Fixed Interest Rate Vary?

Fixed interest rates vary by the lender but typically range between 3 and 10 percent depending on the borrower’s credit rating. The fixed interest rate depends on the lender’s risk assumption. Therefore, the rate offered to borrowers with poor credit is higher than the rate offered to those with excellent credit. Borrowers find it easier to budget when they know how much their monthly loan payment will be, as fixed interest rates are frequently consistent during the life of the loan.

How Often Do Fixed Interest Rates Change?

Fixed Interest Rates usually stay the same for an agreed-upon period, often around one to five years. The interest rate remains unchanged for one to five years, making the borrower’s monthly loan payment. After the fixed-term ends, lenders raise or lower the interest rate according to financial markets. Lenders often choose to keep the rates the same depending on economic conditions.

Who Benefits from a Fixed Interest Loan?

Fixed-interest loans are advantageous for individuals who require a steady and predictable cash flow because the borrower knows exactly how much interest is paid over the life of the loan rather than a variable rate that increases or decreases over time. Fixed-interest loans attract investors who want to lend money since fixed-interest protects against rising interest rates. Homeowners often benefit from fixed rates, granting greater financial stability during repayment, especially with mortgage rates.

What are the Limitations of Fixed Interest?

Listed below are the limitations of fixed interest in the context of mortgage rates.

  • Lower Returns. Fixed-interest investments typically offer lower returns than other investments, as fixed-interest limits the investment to a certain rate of return over a set period. A lower return is adequate for some investors’ needs; it is important to consider alternative options that offer higher potential returns.
  •  Limited Access to Funds. Fixed-interest investments often require that the investor keep money tied up for the entire term and have limited access to funds within those time frames, which makes it difficult to use as part of a short-term strategy since there are regular withdrawal or early termination fees associated with such accounts if funds are accessed before the full term is met.
  •  Fixed Rate Risk. Fixed-interest investments carry a fixed rate risk in that the value is diminished if market rates rise higher than initially agreed upon when the account was opened. In many cases, market fluctuation is not an issue but potentially leads to losses if market conditions change suddenly and unexpectedly during the agreement term.
  •  Inflation Risk. Another limitation of fixed interest investment is inflation risk, which occurs when inflation outstrips returns made on the investment by more than expected amounts over time, thus reducing purchasing power due to increasing prices and fixed income generated by the investment.
Fixed interest rate statistics

Is Fixed Interest Better for Investing?

Yes, fixed interest is good for investing because it provides a predictable return that does not fluctuate with the stock market. It is relatively low risk, and the potential for capital growth is lower than other types of investments. The main downside to fixed-interest investing is that the returns are typically lower than other investments, such as stocks and property. On the other hand, there are variable interest rates investments, which may offer higher returns but with a higher level of risk due to their fluctuating nature.

Below are some statistics about fixed interest:

The average fixed interest rate for a 15-year mortgage5.5%
The average fixed interest rate for a 5/1 ARM4.5%
Average fixed interest rate for a 5/1 ARM3.5%
Statistics about fixed interest

What Types of Investments Make Use of Fixed Interest?

Listed below are the types of investments that make use of fixed interest.

  • Bonds. These are debt securities issued by governments, companies, or other entities with a fixed rate of return throughout the bond’s life until it matures. They can be purchased using various payment methods, including credit cards.
  •  Certificates of Deposit (CDs). Similarly to bonds, CDs provide a fixed rate of return for an agreed period and are purchased through financial institutions like banks or credit unions. You may find the option to use credit cards for payment at some institutions.
  •  Treasury Bills. T-bills are short-term government securities ranging from 4 weeks to 12 months and are considered safe since the US government backs the bills. Treasury bills offer higher returns than savings accounts but come with less risk than stock market investments. It is rare, but some platforms might allow using credit cards to buy these.
  •  Money Market Accounts. These are high-yield savings accounts offered by many banks or credit unions which provide a competitive fixed interest rate on deposits up to certain limits with no risk involved since deposits are FDIC insured up to $250,000 (or more). While opening an account, some banks may allow initial funding with credit cards.

Bonds, certificates of deposit, treasury bills, and money market accounts pay a fixed interest rate. Fixed interest rates allow investors to plan investments and factor in expected return rates to assist in making decisions aligned with financial goals. The reason for using fixed interest is to protect investors from exposure to the volatility and risk associated with variable or fluctuating returns, such as those in an adjustable-rate mortgage. On the other hand, the initial interest rate in adjustable-rate mortgages can be lower than fixed interest rates, which may appeal to some investors.

Frequently Asked Questions

What is fixed interest, and how does it differ from variable or floating interest rates?

Fixed interest maintains the same percentage rate over the full loan term while variable rates fluctuate based on market indexes during the repayment period.

Could you explain the formula used to calculate fixed interest payments on a loan?

Fixed interest payments are calculated by multiplying the loan principal by the annual percentage interest rate, then dividing by the number of payment periods per year.

What are the advantages and disadvantages of opting for a fixed interest rate when taking out a loan?

Advantages include predictable payments and stability while disadvantages include less flexibility to benefit from rate decreases. Variable rates offer the inverse pros and cons.

Can you provide examples of common loan types that utilize fixed interest rates, and how do they benefit borrowers?

Mortgages, auto loans, personal loans and student loans often have fixed rates which help borrowers by making monthly payments predictable and stable over the full repayment term.

How do changes in the economic environment or market conditions impact fixed interest rates on loans, and what should borrowers consider when choosing a fixed interest loan in a dynamic financial landscape?

Increasing interest rates may raise costs for new fixed rate loans but existing fixed rate loans are not impacted. Borrowers should weigh future economic stability and budget needs when selecting fixed interest loan terms.

Kathy Jane Buchanan

Kathy Jane Buchanan has more than 10 years of experience as an editor and writer. She currently worked as a full-time personal finance writer for PaydayChampion and has contributed work to a range of publications expert on loans. Kathy graduated in 2000 from Iowa State University with degree BSc in Finance.