An EMI, or equated monthly instalment, is the fixed amount you pay your lender every month until a loan is repaid. Each EMI covers two things: interest on the amount you still owe, and a part of the principal. Because the EMI stays the same while your outstanding balance falls, the split between interest and principal changes every month.
Understanding how EMI is calculated helps you compare loan offers, choose a sensible tenure and decide whether prepaying is worth it. This guide explains the formula in plain language, works through examples for home, car and personal loans, and shows how much a single prepayment can save.
The EMI formula
Banks and NBFCs in India use the standard reducing-balance formula:
EMI = P × r × (1 + r)^n ÷ ((1 + r)^n − 1)
Where:
- P is the principal, the amount you borrow.
- r is the monthly interest rate, which is the annual rate divided by 12 and then by 100. For 8.5% a year, r = 8.5 ÷ 12 ÷ 100 = 0.0070833.
- n is the number of monthly instalments. A 20-year loan has n = 240.
You do not need to do this by hand; any EMI calculator does it instantly. But knowing the inputs shows you which levers change your EMI: the amount, the rate and the tenure.
Worked example: a home loan
Say you borrow ₹30 lakh at 8.5% a year for 20 years.
- Monthly rate r = 0.0070833
- Number of instalments n = 240
- EMI ≈ ₹26,035
Over 240 months you pay about ₹62.48 lakh in total, of which about ₹32.48 lakh is interest. That is more than the amount you borrowed, which is normal for a long home loan.
How tenure and rate change the picture
| Loan | Rate | Tenure | EMI | Total interest |
|---|---|---|---|---|
| ₹30 lakh | 8.5% | 20 years | ₹26,035 | ₹32.48 lakh |
| ₹30 lakh | 8.5% | 25 years | ₹24,157 | ₹42.47 lakh |
| ₹30 lakh | 9.0% | 20 years | ₹26,992 | ₹34.78 lakh |
Stretching the tenure from 20 to 25 years lowers the EMI by under ₹1,900 a month but adds about ₹10 lakh of interest. A half-point rise in the rate adds almost ₹1,000 to the EMI and about ₹2.3 lakh of interest over 20 years. This is why a slightly lower rate or a shorter tenure is worth chasing.
Worked examples: car and personal loans
Shorter loans have much lower total interest, even when the rate is higher.
| Loan | Rate | Tenure | EMI | Total interest |
|---|---|---|---|---|
| Car loan, ₹8 lakh | 9% | 5 years | ₹16,607 | ₹1.96 lakh |
| Personal loan, ₹5 lakh | 11% | 3 years | ₹16,369 | ₹89,297 |
The rates above are only examples for the arithmetic. Actual rates depend on the lender, your credit score, income and the type of loan, and personal loan rates in particular vary widely.
Why your early EMIs are mostly interest
Interest each month is charged on the outstanding balance. At the start, the balance is at its highest, so most of your EMI goes to interest.
In the home loan example, the first EMI of ₹26,035 breaks down as:
- Interest: ₹30,00,000 × 0.0070833 = ₹21,250
- Principal: ₹26,035 − ₹21,250 = ₹4,785
So in month one, only about 18% of your payment reduces the loan. As the balance falls, the interest portion shrinks and the principal portion grows. In the last years of the loan, almost all of each EMI goes to principal. A month-by-month table of this split is called an amortisation schedule, and it is the best way to see where your money actually goes.
How prepayment cuts interest
Because interest is charged on the outstanding balance, any extra payment that reduces the principal saves interest for the rest of the loan. The earlier you prepay, the bigger the saving.
Take the same ₹30 lakh, 8.5%, 20-year loan. Suppose you make a one-time prepayment of ₹1 lakh after the first year and keep paying the same EMI:
- The loan finishes in about 222 months instead of 240, roughly 18 months sooner.
- Total interest falls from about ₹32.48 lakh to about ₹28.78 lakh, a saving of around ₹3.7 lakh from a single ₹1 lakh prepayment.
When you prepay, lenders usually let you choose between keeping the EMI the same and shortening the tenure, or keeping the tenure and lowering the EMI. Reducing the tenure generally saves more interest; reducing the EMI eases your monthly budget.
Before prepaying, check your loan terms. For floating-rate loans taken by individuals for non-business purposes, RBI rules do not allow lenders to charge prepayment or foreclosure penalties. Fixed-rate loans and some other loan types may carry a charge. It is also sensible to keep an emergency fund before putting spare cash into a prepayment.
What happens when rates change
Most home loans in India are floating-rate loans linked to an external benchmark such as the RBI repo rate. When the benchmark changes, your interest rate changes too. Lenders typically respond by changing the tenure, the EMI, or both. If rates rise and only the tenure is extended, you could end up paying for many more years without noticing. Check your loan statement after each rate change and ask your lender about your options.
Other costs to include
The EMI is not the full cost of a loan. When comparing offers, also look at:
- Processing fees and any documentation or legal charges.
- Insurance bundled with the loan, which is often optional.
- Late payment charges and the effect of missed EMIs on your credit score.
- Tax benefits, if any, which depend on the loan type and the tax regime you choose. Home loan interest deductions, for example, mostly apply under the old regime; see our guide to the new vs old tax regime for FY 2025-26.
A simple checklist before you borrow
- Keep your total EMIs to a comfortable share of your take-home pay, leaving room for savings and emergencies.
- Compare offers on the rate and all fees, not just the EMI.
- Pick the shortest tenure you can comfortably afford.
- Plan regular prepayments, even small ones, especially in the early years.
- Review your loan after every rate change.
Calculate it on your phone
Advance Finance Calculator is our Android app for Indian personal finance. Its loan tools cover EMI, full amortisation schedules, moratoriums, extra repayments, interest-rate changes, loan expenses and interest-saver scenarios, so you can model exactly the comparisons in this article and save them side by side. The same app includes SIP, FD, RD, PPF and post office scheme calculators; if you are deciding between investing and prepaying, our guide to SIP vs FD returns is a good next read.
The figures in this article are illustrative and rounded. Your lender's exact calculation may differ slightly because of rounding, the date your EMIs start and fees; always confirm with your lender.