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When you take a home, car or personal loan, the bank quotes one number that matters every month: the EMI, or Equated Monthly Instalment. It stays the same for years, yet what happens inside that payment changes every single month. Once you understand how it is calculated, you can compare offers properly and save a surprising amount of money.
The EMI formula
Every bank in India uses the same reducing-balance formula:
EMI = P × r × (1 + r)n ÷ ((1 + r)n − 1)
- P is the principal — the amount you borrow.
- r is the monthly interest rate: the annual rate ÷ 12 ÷ 100. So 9% a year becomes 0.0075.
- n is the number of monthly instalments: 20 years = 240 months.
The formula looks intimidating, but its job is simple: find the one fixed payment that, paid every month, covers the interest on the remaining balance and clears the loan exactly at the end.
Example: a ₹10,00,000 loan at 9% for 20 years gives r = 0.0075 and n = 240. Plugging these in, the EMI is ₹8,997. Over 240 months you pay about ₹21.59 lakh in total — of which ₹11.59 lakh is interest, more than the amount you borrowed.
Where your EMI actually goes
Each month the bank first charges interest on the outstanding balance. Whatever is left from your EMI reduces the principal. Because the balance is highest at the start, the interest share is highest at the start too.
| Month | Interest part | Principal part | Balance left |
|---|---|---|---|
| 1 | ₹7,500 | ₹1,497 | ₹9,98,503 |
| 120 (year 10) | ₹5,354 | ₹3,643 | ₹7,10,259 |
| 240 (last) | ₹67 | ₹8,930 | ₹0 |
₹10 lakh at 9% for 20 years, EMI ₹8,997.
Notice that after ten years of payments you still owe about ₹7.1 lakh of the original ₹10 lakh. This is why part-prepayments made early in a loan have such a big effect — every rupee of principal you clear early stops attracting interest for all the remaining years.
How tenure changes the picture
Stretching the loan lowers the EMI, but the bank collects interest for longer. Here is the same ₹10 lakh loan at 9% across different tenures:
| Tenure | EMI | Total interest |
|---|---|---|
| 10 years | ₹12,668 | ₹5.20 lakh |
| 15 years | ₹10,143 | ₹8.26 lakh |
| 20 years | ₹8,997 | ₹11.59 lakh |
| 25 years | ₹8,392 | ₹15.18 lakh |
| 30 years | ₹8,046 | ₹18.97 lakh |
Going from 20 to 30 years cuts the EMI by only ₹951 a month, but adds more than ₹7 lakh in interest. On the other hand, moving from 20 to 15 years costs ₹1,146 more per month and saves over ₹3.3 lakh.
A practical rule: pick the shortest tenure whose EMI stays under about 35–40% of your take-home pay, leaving room for savings and emergencies.
How much does the interest rate matter?
More than most borrowers expect. Taking the ₹10 lakh, 20-year loan again:
- At 9%, the EMI is ₹8,997 and total interest is ₹11.59 lakh.
- At 8.5%, the EMI drops to ₹8,678 and total interest to ₹10.83 lakh.
A half-percent difference saves about ₹319 every month and ₹76,000 over the loan — on a ₹50 lakh home loan, multiply that by five. This is why it is worth comparing lenders, negotiating, and checking whether a balance transfer makes sense once your credit score improves (after accounting for processing fees).
Fixed vs floating rates
With a fixed rate, your rate and EMI stay the same for the agreed period. With a floating rate, the rate moves with the lender’s benchmark (often linked to the RBI repo rate). When rates rise, most banks keep your EMI unchanged and quietly extend the tenure instead. It is worth checking your loan statement every year — a few rate hikes can add years to a loan without you noticing.
Things the EMI does not include
The EMI covers only principal and interest. Budget separately for:
- Processing fees (often 0.25%–1% of the loan, plus GST).
- Loan or property insurance, sometimes bundled into the loan amount.
- Prepayment or foreclosure charges — usually nil for floating-rate home loans to individuals, but common on personal and fixed-rate loans.
- Late payment penalties if an EMI bounces.
Check any loan in seconds
You don’t need to do this maths by hand. Enter the amount, rate and tenure in our EMI calculator to see your EMI, total interest and total payment instantly — then try a shorter tenure or a lower rate to see how much you could save before you sign.
Free toolTry the EMI CalculatorWork out the monthly instalment, total interest and total cost of any loan.Frequently asked questions
Why does my bank's EMI differ slightly from a calculator?
Banks may round the EMI up to the next rupee, start interest from the disbursement date (creating a small first-month 'broken period' interest), or add insurance and fees to the loan amount. The core formula is the same.
Does the EMI change when the repo rate changes?
For floating-rate loans the interest rate changes with the bank's benchmark. Most banks keep the EMI the same and change the remaining tenure, unless you ask them to change the EMI instead.
Is it better to choose the lowest EMI possible?
Not usually. The lowest EMI comes from the longest tenure, which costs the most interest. Choose the shortest tenure whose EMI fits comfortably in your monthly budget.
Written by the Toolsopedia team. Spotted an error? Tell us and we’ll fix it.