Rule of 78: Definition, How It Works, Types, and Examples


The Rule of 78 is a complex interest calculation method employed by some lenders. It allocates a greater share of interest to the earlier stages of a loan, which can disadvantage borrowers, especially if they plan to pay off their loans early. This article delves into the Rule of 78, explaining its mechanics, how it differs from simple interest, and its implications for borrowers.

What is the rule of 78?

The rule of 78 is a method used by certain lenders to calculate interest charges on a loan. This calculation approach allocates a substantial portion of interest payments to the early months of a loan, which may not be in the borrower’s favor, particularly if they aim to settle the loan ahead of schedule.

Understanding the rule of 78

The rule of 78 is a specific method of calculating interest that gives significant weight to the early months of a borrower’s loan cycle. This emphasis on front-loading interest benefits the lender, increasing their profits. Typically, the rule of 78 is applied to fixed-rate non-revolving loans. It’s crucial for borrowers to comprehend this calculation method, especially if they have intentions of early loan repayment.

The rule of 78 dictates that borrowers must pay a substantial portion of the interest during the initial stages of the loan, resulting in higher costs compared to a regular loan with a consistent interest distribution.

Calculating rule of 78 loan interest

The rule of 78 loan interest calculation is more intricate than a simple annual percentage rate (APR) loan. In both loan types, the total interest paid will be the same if the borrower makes payments for the entire loan term without prepayment. However, the rule of 78 methodology assigns more weight to the early months of the loan cycle and is often used by short-term installment lenders, especially those catering to subprime borrowers.

In a 12-month loan, the lender calculates the sum of digits from 1 to 12, which equals 78:

1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 + 11 + 12 = 78

For a one-year loan, the sum is 78, which explains the term “rule of 78.” For a two-year loan, the sum becomes 300.

Once the sum of the months is determined, the lender assigns weights to interest payments in reverse order. In a one-year loan, the weighting factor is 12/78 in the first month, 11/78 in the second month, 10/78 in the third month, and so on. For a two-year loan, the weighting factor is 24/300 in the first month, 23/300 in the second month, 22/300 in the third month, and so forth.

Rule of 78 vs. simple interest

When repaying a loan, the payments consist of two parts: the principal and the interest. The rule of 78 assigns more interest to the early payments than a simple interest method. If the loan is not paid off early, the total interest paid using simple interest and the rule of 78 will be the same.

However, due to the rule of 78’s front-loading of interest, settling the loan early will result in the borrower paying slightly more interest overall.

In 1992, legislation made this type of financing illegal for loans in the United States with a duration of more than 61 months. Some states have imposed even stricter restrictions for loans of less than 61 months, while others have entirely banned the practice. If you’re uncertain, check with your state’s Attorney General’s office before entering into a loan agreement with a rule of 78 provision.

The difference in savings from early prepayment on a rule of 78 loan versus a simple interest loan is not significantly substantial for shorter-term loans. For instance, a borrower with a two-year $10,000 loan at a 5% fixed rate would pay a total interest of $529.13 over the entire loan term for both rule of 78 and simple interest loans.

In the first month of a rule of 78 loan, the borrower would pay $42.33, while in the first month of a simple interest loan, the interest is calculated as a percentage of the outstanding principal, resulting in a payment of $41.67. If a borrower intends to pay off the loan after 12 months, they would be required to pay $5,124.71 for the simple interest loan and $5,126.98 for the rule of 78 loan.

Weigh the risks and benefits

Here is a list of the benefits and drawbacks to consider.

  • May be suitable for lenders offering short-term loans.
  • Can maximize profits by front-loading interest payments.
  • Ensures a consistent profit for lenders.
  • Disadvantages borrowers who intend to prepay their loans.
  • Limited to certain types of loans.
  • Complex calculation method that may be difficult for borrowers to understand.

Frequently asked questions

Is the rule of 78 commonly used by lenders?

Not as commonly as in the past. In 1992, legislation in the United States restricted its use for loans with durations of more than 61 months, and some states have imposed even stricter regulations.

Should I consider the rule of 78 when taking out a loan?

It depends on the type of loan and your repayment plans. If you intend to pay off your loan early, the rule of 78 may result in higher interest costs. Make sure to carefully review the terms of your loan agreement.

Are there alternatives to the rule of 78?

Yes, many lenders now use simpler interest calculation methods, such as the simple interest formula. It’s essential to understand the interest calculation method used in your loan to make informed decisions about your repayment strategy.

Can I request a change in the calculation method if I have a Rule of 78 loan?

Generally, loan terms and calculation methods are predetermined in the loan agreement. If you have concerns about the calculation method, it’s advisable to discuss this with your lender before signing the agreement. However, many lenders have switched to simpler interest calculation methods in recent years.

Are there any advantages to the Rule of 78 for borrowers?

For borrowers who don’t plan on early loan repayment, the Rule of 78 may not significantly impact their interest costs. However, it’s essential to understand that this calculation method can result in slightly higher overall interest expenses, so it’s crucial to consider your repayment strategy and loan terms carefully.

How can I identify if my loan uses the Rule of 78 calculation method?

You can find information about the interest calculation method used in your loan agreement. If you’re unsure, reach out to your lender or review the terms and conditions provided when you took out the loan. Additionally, some states require lenders to disclose the calculation method in the loan agreement.

Key takeaways

  • The rule of 78 is a method used by certain lenders to calculate interest on loans, emphasizing early interest payments.
  • It may result in higher interest costs for borrowers who plan to pay off their loans ahead of schedule.
  • Legislation in 1992 made the rule of 78 illegal for loans with durations of over 61 months in the United States.
  • Borrowers should carefully consider the interest calculation method used in their loans and its implications for their repayment strategy.
View Article Sources
  1. Computing Interest Rebates under the Rule of 78ths – St. Mary’s University
  2. 15 U.S. Code § 1615 – Prohibition on use of “Rule of 78’s” – Legal Information Institute
  3. WHAT IS THE RULE OF 78s – Mississippi
  4. RULE OF 78s GUIDELINES – New Mexico
  5. How to Finance a Used Car – SuperMoney