What an EMI is
An EMI — equated monthly instalment — is the fixed amount you pay a lender every month so that the loan is fully repaid, interest included, by the end of the tenure. Every EMI is split internally: part of it pays that month’s interest on the balance still outstanding, and the rest reduces the balance. Early in the loan the interest share dominates; as the balance shrinks, more of each identical instalment goes to principal.
The formula this calculator uses
The standard reducing-balance formula used by banks: EMI = P × r × (1 + r)n ÷ ((1 + r)n − 1), where P is the loan amount, r the monthly rate (annual rate ÷ 12 ÷ 100) and n the number of monthly instalments. Total repayment is EMI × n; total interest is that minus the principal.
A worked example: ₹25,00,000 borrowed at 8.5% per year for 20 years gives r = 0.708% per month and n = 240. The EMI works out to about ₹21,696 per month, roughly ₹52.1 lakh repaid in total — of which about ₹27.1 lakh is interest, more than the amount borrowed. That is normal for long tenures: time, not the rate alone, is what makes interest accumulate.
Tenure versus EMI — the real trade-off
Stretching the tenure lowers the monthly payment but raises the total interest sharply. The same ₹25 lakh at 8.5% costs about ₹31,000 a month over 10 years (≈ ₹12.2 lakh interest) versus ₹21,696 over 20 years (≈ ₹27.1 lakh interest) — the smaller EMI more than doubles the interest bill. Try a few tenures in the calculator and watch the “total interest” card rather than the EMI alone; the affordable EMI and the cheap loan are usually different choices.
Flat rate is not the same as reducing rate
Some lenders — especially for two-wheeler, appliance and small personal loans — quote a flat rate, which charges interest on the original principal for the entire tenure even as you repay it. A 10% flat rate costs roughly what a 17–19% reducing-balance rate costs over typical tenures. This calculator uses the reducing-balance method, which is how home loans, car loans and most bank personal loans are quoted. When comparing offers, always compare on the reducing-balance (effective) rate.
