BCBetter Calculators

APR Calculator

Estimate the Annual Percentage Rate (APR) of a loan including interest and fees.

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Enter your values and click Calculate

How It Works

The calculation proceeds in three steps. Step 1: compute the monthly payment using the standard amortization formula: M = P × (r × (1+r)^n) ÷ ((1+r)^n − 1), where P is the loan amount, r is the monthly interest rate (annual rate ÷ 12), and n is the total number of monthly payments. Step 2: calculate the Total Finance Charge = Total Interest + Fees, where Total Interest = (M × n) − P. Step 3: estimate APR using the constant ratio approximation: APR = (24 × TotalFinanceCharge × 100) ÷ (Net Principal × (n + 1)), where Net Principal = Loan Amount − Fees. This formula approximates the more complex IRR (Internal Rate of Return) calculation used by banks. For a zero-fee loan, APR will approximately equal the nominal interest rate — any gap is a small artifact of the constant ratio approximation method. For loans with significant origination fees, the APR can be 1–3 percentage points higher than the nominal rate, which is why comparing loan offers by APR rather than interest rate is essential.

Examples

Car Loan with Doc Fees
A $20,000 auto loan at 6% over 5 years with a $500 document fee.
Result: Estimates an APR of 7.086% and a total cost of $23,699.65.
Personal Loan with Origination Fee
A $10,000 personal loan at 8% over 3 years with a $300 origination fee.
Result: Estimates an APR of 10.155%.
Zero-Fee Loan
A $5,000 loan at 4% for 2 years with no fees.
Result: APR exactly matches the nominal rate at 4.000%.

Frequently Asked Questions

What is the difference between APR and interest rate?
The interest rate is the base cost of borrowing the principal — it determines only your monthly payment. APR includes both the interest rate and all upfront fees (origination charges, closing costs, document fees), expressed as an equivalent annual rate. Two loans with the same interest rate but different fees will have different APRs, and the higher-APR loan always costs more in total. Federal law in the US (Regulation Z under TILA) requires lenders to disclose APR precisely because the interest rate alone is insufficient for comparison.
Why is the APR higher than the interest rate?
Because APR includes upfront fees that are effectively additional interest spread over the loan term. A $500 origination fee on a $10,000 loan represents 5% of the principal paid upfront — when amortized over 3 years, it adds roughly 1–2 percentage points to the effective annual rate. The shorter the loan term, the more dramatically fees inflate the APR, because the fee is spread over fewer payments.
Should I compare loans by APR or interest rate?
Always compare by APR when evaluating competing loan offers — it standardizes the total cost by incorporating fees into a single rate. A loan advertised at 5% with $2,000 in fees may cost more than a 5.5% loan with no fees, depending on the loan size and term. APR makes that comparison transparent and is the legally required disclosure metric for consumer loans in the United States.

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