How EMI Works: The Mechanics of Principal, Interest, and Loan Amortization
What Is an Equated Monthly Installment (EMI)?
An EMI is a fixed monthly rupee payment made by a borrower to a lender on a specified calendar date each month. Each EMI payment is composed of two distinct parts:
- Principal Component: The portion that directly reduces your outstanding borrowed loan balance.
- Interest Component: The fee charged by the bank or NBFC for borrowing the capital.
The Mathematical EMI Formula
All scheduled banks in India use the universal annuity amortization formula:
Where: P = Principal Loan Amount, r = Monthly Interest Rate (Annual Rate / 12 / 100), and n = Number of monthly installments.
Reducing Balance vs. Flat Rate Loans
Always ensure your loan operates on a Reducing Balance schedule. Under a reducing balance loan, interest is calculated only on the remaining unpaid principal at the end of each month.
In contrast, unscrupulous consumer electronics financing or flat-rate two-wheeler loans calculate interest on the full original principal for the entire duration, doubling the effective annual interest rate (e.g., a "10% flat rate" is approximately 18% to 19% effective reducing APR!).
Calculate Your Amortization Schedule
Use our interactive EMI calculator to view the month-by-month principal vs interest split.
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