Loan Payment Calculator: Amortization and Interest
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Loan Payment Calculator

Calculate the fixed monthly payment, total interest, and full repayment cost for any installment loan (mortgage, personal, or commercial).

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The Amortization Formula for Fixed-Rate Loans

A standard **installment loan** is paid off over time through regular, fixed payments. The method used to calculate these payments is known as **Amortization**. Each payment covers both a portion of the interest accrued since the last payment and a portion of the loan's principal.

Calculating the Payment:

The calculator uses the general loan payment formula, where the payment ($M$) is fixed: $$ M = P \frac{i(1+i)^n}{(1+i)^n - 1} $$ Where:

  • $P$ is the **Principal** Loan Amount.
  • $i$ is the **Periodic Interest Rate** ($\frac{\text{APR}}{\text{Payments Per Year}}$).
  • $n$ is the **Total Number of Payments** ($\text{Loan Term in Years} \times \text{Payments Per Year}$).

Key Financial Metrics:

This tool helps determine:

  • **Loan Payment:** The fixed amount you must pay each period (e.g., monthly).
  • **Total Interest Paid:** The total amount of money paid solely to the lender for the privilege of borrowing the principal.
  • **Total Repayment Cost:** The sum of the Principal Loan Amount and the Total Interest Paid.