Annual Percentage Rate Calculator

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Reviewed by: **Dr. Jane Austen, PhD (Financial Mathematics)**
Specialist in consumer credit regulations and the true cost of borrowing across various financial products.

The **Annual Percentage Rate (APR) Calculator** determines the true, comprehensive cost of a loan by factoring in both the simple interest rate and required upfront fees. This calculator can solve for the missing variable among Principal, Monthly Payment, Interest Rate, or Term, and always outputs the calculated APR.

Annual Percentage Rate Calculator

Instructions: Enter values for at least three of the four main loan parameters (P, M, $R_{int}$, $N$), plus the Upfront Fee, to calculate the accurate APR.


Loan Parameters (P, F, V, Q)

Annual Percentage Rate (APR) Formula Principle

APR is the discount rate ($R_{APR}$) that makes the Present Value (PV) of all expected payments equal to the net loan amount received by the borrower ($P – F_{upfront}$).

PV of Payments = Net Principal:

$$\sum_{t=1}^{N} \frac{M}{(1 + R_{APR}/12)^{t}} = P – F_{upfront}$$

Since APR cannot be solved directly, it requires iterative calculation (like IRR) where $M$ is first calculated using the nominal rate $R_{int}$:

$$M = P \left[ \frac{i(1+i)^n}{(1+i)^n – 1} \right], \text{ where } i = R_{int}/1200$$ Formula Source: Investopedia: Annual Percentage Rate

Variables Explained (P, F, V, Q – Loan Parameters)

  • $P$ (Principal Amount): The total amount borrowed from the lender.
  • $F$ (Monthly Payment): The amount paid monthly, calculated using the nominal rate.
  • $V$ (Nominal Rate, $R_{int}$): The advertised interest rate, excluding fees.
  • $Q$ (Loan Term, $N$): The total duration of the loan in months.
  • $F_{upfront}$ (Upfront Fees): All mandatory fees (e.g., origination, closing costs) paid at the start.

Related True Cost Calculators

Analyze the full cost and value of your borrowing:

What is Annual Percentage Rate (APR)?

The Annual Percentage Rate (APR) is a standardized measure that represents the true annual cost of a loan to the borrower. Unlike the simple nominal interest rate, the APR incorporates not only the interest charged on the principal but also certain mandatory fees and costs (such as origination fees, discount points, or prepaid interest) paid by the borrower to obtain the loan.

The U.S. Truth in Lending Act requires lenders to disclose the APR so consumers can easily compare the true costs of different loan products, even if they have different fee structures. A loan with a lower nominal interest rate but higher upfront fees may actually have a higher APR than a loan with a slightly higher nominal rate but zero fees.

In essence, the APR calculation determines the single effective interest rate that would result in the same total cash flow between the borrower and lender over the full term, making it the most reliable metric for comparison.

How to Calculate APR (Example)

Assume a \$10,000 Principal ($P$) at a Nominal Rate ($R_{int}$) of 5.0% for 24 months ($N$), with a \$200 Upfront Fee ($F_{upfront}$):

  1. Step 1: Calculate the Monthly Payment ($M$)

    Using the standard amortization formula for $P=\$10,000, R_{int}=5.0\%, N=24$, the Monthly Payment ($M$) is calculated to be **\$438.71**.

  2. Step 2: Determine Net Principal

    The borrower only receives $\text{\$10,000} – \text{\$200} = \mathbf{\$9,800}$.

  3. Step 3: Iteratively Solve for APR

    The APR is the rate $R_{APR}$ that makes the Present Value of 24 payments of \$438.71 equal to the Net Principal of \$9,800. The calculated APR is approximately $\mathbf{7.25\%}$.

Frequently Asked Questions (FAQ)

What is the difference between APR and Interest Rate?

The Interest Rate is the primary cost of borrowing, used to calculate interest payments. The APR is a broader measure that includes the interest rate plus certain upfront fees, providing the total cost of the loan expressed as an annual rate.

Why is APR always higher than the Interest Rate?

APR is generally higher than the nominal interest rate because it includes fees (like origination fees) that are not part of the standard interest calculation, increasing the overall cost of the loan to the borrower.

Does APR include late payment fees?

No. APR only includes mandatory, non-contingent costs required to obtain the loan. It does not include variable fees like late payment charges, appraisal fees, or property taxes.

When is APR most important?

APR is most important when comparing two loan offers, especially if one has a lower interest rate but higher upfront fees, or vice-versa. Always use the APR for an apples-to-apples comparison of loan cost.

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