An EMI (equated monthly instalment) is the fixed amount you pay your bank every month until a loan is cleared. It looks like a single number, but it is built from three inputs: how much you borrow, the interest rate and the tenure. Once you know how they combine, you can compare loans honestly and see which changes save real money.
The EMI formula
EMI = P × r × (1 + r)ⁿ ÷ ((1 + r)ⁿ − 1) P = loan amount (principal) r = monthly interest rate = yearly rate ÷ 12 ÷ 100 n = number of monthly instalments = years × 12
Banks in India charge interest on the reducing balance: every month, interest is worked out on what you still owe, not on the original amount. That is why the formula has the compounding term (1 + r)ⁿ.
A worked example
You borrow ₹10,00,000 at 9% a year for 20 years.
- Monthly rate r = 9 ÷ 12 ÷ 100 = 0.0075
- Number of months n = 20 × 12 = 240
- Put them in the formula: EMI ≈ ₹8,997
- Total paid = 8,997 × 240 ≈ ₹21,59,342, so the interest is about ₹11,59,342, more than the loan itself.
How tenure changes what you pay
Same ₹10 lakh at 9%, different tenures:
| Tenure | EMI | Total interest |
|---|---|---|
| 10 years | ₹12,668 | ₹5,20,109 |
| 15 years | ₹10,143 | ₹8,25,680 |
| 20 years | ₹8,997 | ₹11,59,342 |
Doubling the tenure from 10 to 20 years lowers the EMI by about a quarter, but more than doubles the interest. A longer tenure is a way to make the monthly payment affordable, not a way to make the loan cheaper.
Why early EMIs are mostly interest
In month one of the example, interest is ₹10,00,000 × 0.0075 = ₹7,500, so only about ₹1,497 of the ₹8,997 EMI reduces your debt. Each month the balance falls a little, the interest part shrinks and the principal part grows. The amortisation schedule in the calculator shows this year by year.
Ways to pay less interest
- Prepay early. A part-payment in the first few years removes the balance that would have been charged interest for decades. Choose to keep the EMI and shorten the tenure for the biggest saving.
- Pick the shortest tenure you can afford. Keep a buffer for emergencies, but each year removed saves a lot.
- Compare the rate, not the EMI. A 0.5% lower rate over 20 years saves more than most people expect. Use the calculator for each offer.
- Check fees. Processing fees, insurance and GST on fees are extra and are not part of the EMI formula.
Frequently asked questions
Is EMI calculated on a flat or reducing-balance rate?
Home, car and most personal loans from banks use the reducing-balance method shown here. Some retailers and small lenders advertise flat rates, where interest is charged on the full amount for the whole term. A flat rate costs much more than the same number as a reducing rate, so ask which one is quoted.
Does the EMI include the processing fee?
No. The EMI covers principal and interest only. Fees, insurance and taxes on them are separate.
What happens to my EMI if I prepay?
That depends on your bank and your choice. Usually you can keep the EMI the same and shorten the loan, or keep the tenure and lower the EMI. The first saves more interest.