Effective Interest Rate Calculator

Calculate the true cost of borrowing with the Effective Interest Rate. Compare loans, mortgages, and credit products by accounting for compounding frequency and additional fees.

✓ True Borrowing Cost ✓ Fee Integration ✓ Loan Comparison

Effective Interest Rate Calculation

Loan Details

Principal amount borrowed

Stated annual interest rate

How often interest compounds

Length of loan in years

Additional Costs & Fees

Upfront loan processing fee

Total closing and administrative costs

Discount points (% of loan amount)

Insurance, appraisal, and other fees

Payment Options

How often payments are made

Penalty for early repayment (% of balance)

EIR Formula

EIR = (1 + r/n)^n - 1
Where:
EIR = Effective Interest Rate
r = Nominal interest rate
n = Compounding frequency
With Fees: Adjusted for upfront costs

Loan Examples

30-Year Mortgage
$300k loan, 6.5% rate, monthly payments
Auto Loan
$25k loan, 4.5% rate, 5 years
Personal Loan
$15k loan, 12% rate, 3 years

Interest Rate Types

Nominal Rate: Stated annual rate
Effective Rate: True annual cost with compounding
APR: Includes fees and costs
Real Rate: Adjusted for inflation
Fixed Rate: Constant throughout term
Variable Rate: Changes with market

Cost Factors

✓ Compounding frequency
✓ Origination fees
✓ Closing costs
✓ Discount points
✓ Insurance premiums
✓ Prepayment penalties
Advertisement

Understanding Effective Interest Rate

The Effective Interest Rate (EIR) represents the true annual cost of borrowing, accounting for compounding frequency and all associated fees and costs.

  • True Cost: Shows actual annual borrowing cost
  • Compounding Effect: Includes impact of payment frequency
  • Fee Integration: Incorporates all upfront and ongoing costs
  • Comparison Tool: Enables fair comparison between loan offers

EIR Applications

Loan Shopping

Compare different loan offers by looking at the effective interest rate rather than just the nominal rate.

Mortgage Analysis

Evaluate mortgage options including points, fees, and different payment schedules.

Credit Decisions

Make informed borrowing decisions by understanding the true cost of credit.

Financial Planning

Budget accurately by knowing the real cost of financing major purchases.