How EMI Is Calculated: Formula, Examples and How to Pay Less Interest

Every home, car and personal loan in India is repaid in EMIs, Equated Monthly Instalments: the same amount every month until the loan is cleared. The EMI looks simple, but how it's split between interest and principal explains why loans feel slow to shrink, and why a small prepayment can save lakhs. Here's the formula, a worked example and the ways to pay less.

The EMI formula

EMI = P × r × (1 + r)ⁿ ÷ [(1 + r)ⁿ − 1]

• P is the loan amount (principal).
• r is the monthly interest rate: the yearly rate ÷ 12 ÷ 100.
• n is the number of monthly instalments: years × 12.

Over 20 years you pay ₹20,82,776 in total: the ₹10 lakh you borrowed plus ₹10,82,776 of interest.

Where your EMI goes

Each month, interest is charged on the balance still owed, and whatever is left of the EMI repays principal. Early on the balance is large, so most of the EMI is interest. Take a ₹50 lakh home loan at 8.5% for 20 years: the EMI is ₹43,391, and the total interest is ₹54.14 lakh, more than the loan itself.

In the first year, about 81% of what you pay is interest. Only in the later years does most of the EMI go to principal.

How the rate and tenure change the cost

A longer tenure lowers the EMI but sharply raises the total interest:

And even half a percentage point matters over 20 years:

Flat rate vs reducing rate

Home loans charge interest on the reducing balance, as above. Some personal, car and consumer loans quote a flat rate, charged on the full amount for the whole tenure, which looks cheaper than it is. A ₹5 lakh loan at a 7% flat rate for 5 years has an EMI of ₹11,250. That's the same as a reducing rate of about 12.5%. Compare any offer with the flat vs reducing rate calculator.

How to pay less interest

Because interest is charged on the balance, anything that cuts the balance early saves the most. On the ₹50 lakh loan:

• Prepay early, and ask the bank to reduce the tenure rather than the EMI. That saves the most interest. Plan yours with the loan prepayment calculator.
• Pick the shortest tenure whose EMI you can comfortably afford.
• Claim the tax benefit if it helps. In the old tax regime, home-loan interest up to ₹2 lakh a year and principal under 80C are deductible. Whether that beats the new regime is worked out in our old vs new tax regime guide.
• Move to a cheaper lender if your rate is well above the market. Check the costs with the balance transfer calculator.