Tools To India
Loans

How EMI Actually Works

An EMI is fixed, but what sits inside it changes every month. Understanding that split explains almost everything else about borrowing.

Last updated

3 min read

The short version

  • EMI = P × r × (1+r)ⁿ ÷ ((1+r)ⁿ − 1), on a monthly reducing balance.
  • The instalment is constant; the split between interest and principal is not.
  • Early instalments are mostly interest, which is why early prepayment saves so much.
  • A flat rate is roughly 1.8 times more expensive than the same reducing-balance rate.

The formula

Every Indian retail lender uses the standard annuity formula: EMI = P × r × (1+r)ⁿ ÷ ((1+r)ⁿ − 1), where P is the principal, r is the monthly rate (annual rate ÷ 12 ÷ 100) and n is the tenure in months.

What the formula does is find the one fixed monthly payment that clears both interest and principal exactly by the end of the tenure. Three inputs, one output — nothing else affects it.

Why your first instalment barely dents the loan

Interest each month is charged on what you still owe at the start of that month. At the beginning, you owe almost everything, so almost all of the instalment goes to interest.

On a ₹10 lakh loan at 8.5% for 20 years, the EMI is ₹8,678. In the first month, ₹7,083 of that is interest and only ₹1,595 reduces the loan. By year fifteen the proportions have reversed.

Why your first instalment barely dents the loan
MonthInterestPrincipalBalance
1₹7,083₹1,595₹9,98,405
60₹6,441₹2,237₹9,06,673
120₹5,131₹3,547₹7,20,510
180₹3,053₹5,625₹4,25,428
240₹61₹8,617₹0

Flat rate versus reducing balance

A reducing-balance rate charges interest on what you still owe. A flat rate charges interest on the full original amount for the entire tenure, regardless of how much you have repaid.

That difference is large. A "flat 8%" on a five-year loan works out to roughly 14–15% on a reducing balance. Dealers and consumer-finance schemes quote flat rates precisely because the number looks smaller.

When comparing offers, the reliable test is the total amount repayable over the same tenure. Two loans with very different-sounding rates can be compared honestly only that way.

What the EMI formula does not include

  • Processing fees, which are often deducted from the disbursal so you pay interest on money you never received.
  • Documentation, legal and valuation charges.
  • Insurance premiums bundled into the loan.
  • GST on all of the above.
  • Ask the lender for the annual percentage rate that folds these in, rather than the headline interest rate.

Frequently asked questions

Why does my EMI stay the same when the interest rate changes?
On a floating-rate loan, most Indian lenders keep the EMI constant and adjust the tenure instead. A rate rise therefore adds months to your loan rather than rupees to your instalment, which is easy to miss. You can usually ask the lender to raise the EMI and keep the tenure — that costs less overall.
Is a flat rate cheaper than a reducing-balance rate?
Almost never. A flat rate charges interest on the original amount throughout, so you keep paying interest on principal you have already repaid. A flat 8% over five years is roughly 14–15% reducing. Compare the total repayable, not the rate.
When is the best time to prepay?
As early as possible. Early instalments are mostly interest, so removing principal early eliminates interest that would otherwise have accrued for many remaining months. Ask the lender to shorten the tenure rather than reduce the EMI — that saves more.

Sources

Every figure on this page is traceable to the official source below. If a source has changed since the date shown, please tell us and we will correct it.