How to Calculate EMI and Save Lakhs With Loan Prepayment

EMI = P × r × (1 + r)^n ÷ [(1 + r)^n − 1], where P is the loan amount, r is the monthly interest rate (annual rate ÷ 12 ÷ 100) and n is the number of monthly instalments. A ₹50 lakh home loan at 8.5% for 20 years works out to an EMI of ₹43,391.16, and you pay ₹54.14 lakh of interest on top of the ₹50 lakh borrowed. Prepay ₹5 lakh after two years and keep the same EMI, and the loan ends 45 months early with ₹14.57 lakh less interest.

The free EMI calculator gives the monthly EMI, total interest and total payment for any amount, rate and tenure. It doesn't take a prepayment as an input, but you can still use it to check both prepayment options, as shown below with the working.

The EMI formula, step by step

Take the ₹50 lakh loan at 8.5% a year for 20 years.

1. P = ₹50,00,000.
2. Monthly rate r = 8.5 ÷ 12 ÷ 100 = 0.0070833.
3. Number of EMIs n = 20 × 12 = 240.
4. (1 + r)^n = 1.0070833^240 = 5.4412.
5. EMI = 50,00,000 × 0.0070833 × 5.4412 ÷ (5.4412 − 1) = ₹43,391.16.
6. Total paid = 43,391.16 × 240 = ₹1,04,13,878.80, so total interest = ₹54,13,878.80.

The calculator gives the same figures: EMI ₹43,391.16, total interest ₹54,13,878.80, tenure 240 months. It rounds the tenure to whole months, so 20.5 years is treated as 246 EMIs.

Where your EMI goes in the early years

An EMI stays the same every month, but its make-up changes. Interest is charged on the outstanding balance, so at the start almost all of the EMI is interest.

• First EMI: interest = 50,00,000 × 0.0070833 = ₹35,416.67; principal = ₹7,974.50.
• First year: you pay ₹5,20,694 in EMIs, of which ₹4,21,182 is interest and only ₹99,511 reduces the loan.
• After two years: you have paid ₹10,41,388 and still owe ₹47,92,181.

This is why prepaying early is so powerful. Every rupee of principal you remove in year two stops attracting 8.5% interest for the remaining 18 years.

Tenure changes the total cost far more than the EMI

Banks often offer a longer tenure to make the EMI look affordable. Here is the same ₹50 lakh at 8.5% over different tenures, as the calculator shows them.

Stretching from 20 to 30 years cuts the EMI by ₹4,945 a month but adds ₹34.27 lakh of interest. Going the other way, 15 years costs ₹5,846 more a month and saves ₹15.51 lakh. The same pattern holds for smaller loans: ₹10 lakh at 9% costs ₹2.46 lakh of interest over 5 years (EMI ₹20,758.36) but ₹5.20 lakh over 10 years (EMI ₹12,667.58).

Prepayment: reduce the tenure or reduce the EMI

When you prepay, the lender subtracts the amount from your outstanding principal. It then does one of two things: keeps your EMI the same so the loan finishes sooner, or keeps the end date the same and lowers your EMI. The table compares these on the ₹50 lakh loan.

These figures are worked out month by month at 8.5% on the reducing balance, which is the basis of the EMI formula, with a smaller final EMI where the loan ends early. Your lender's statement may differ by a few rupees because of rounding and the date the prepayment is credited.

Checking the "lower EMI" option with the calculator

After 24 EMIs you owe ₹47,92,181. Subtract the ₹5 lakh prepayment to get ₹42,92,181. Enter that in the EMI calculator at 8.5% for the 18 years left: the new EMI is ₹38,863.87, and interest over those 18 years is ₹41,02,416. Add the ₹8,33,569 of interest already paid in the first two years and the total is ₹49,35,985.

Checking the "shorter loan" option

Keep paying ₹43,391 on ₹42,92,181. Enter the balance at 8.5% and try different tenures until the EMI matches yours: 14.25 years (171 months) gives ₹43,376.96, just under your EMI. So the loan closes in about 171 more months, 195 in total, which is 45 months sooner than planned.

Cutting the tenure saves about three times as much here because you keep paying the higher EMI, so more principal goes every month. Cutting the EMI frees ₹4,527 a month, which helps if your budget is tight or you expect a big expense. If you would simply spend the ₹4,527, choose the shorter loan. Lenders handle this differently by default, so tell them in writing which option you want.

Timing matters as much as the amount. The same ₹5 lakh after the 180th EMI saves ₹2.22 lakh, against ₹14.57 lakh after the 24th, because by then most of each EMI is principal anyway.

When prepaying beats investing

A prepayment earns a guaranteed return equal to your loan rate, and the interest you avoid isn't taxed. To decide, compare that with the after-tax return you can expect elsewhere.

• Against a fixed deposit: a 7% FD for someone in the 30% slab leaves about 4.8% after tax and cess (7 × (1 − 0.312)). Prepaying an 8.5% loan wins easily. The FD calculator shows pre-tax maturity values.
• Against equity mutual funds: long-term returns have often been higher than home-loan rates, but they are not guaranteed, and gains above ₹1.25 lakh a year are taxed at 12.5% after a year. Many people split spare money between a SIP and prepayment. Model the SIP side with the SIP calculator, and see lumpsum vs SIP for how market returns compound.
• Tax in the old regime: interest on a self-occupied home loan is deductible up to ₹2 lakh a year (section 24(b), now section 22 of the Income-tax Act, 2025), and principal repayment counts within the ₹1.5 lakh 80C limit. In year one of our example the interest is ₹4.21 lakh, so ₹2.21 lakh of it gets no deduction at all. Prepaying cuts that unrelieved interest first; you only start losing deduction once yearly interest falls below ₹2 lakh.
• Tax in the new regime: there is no deduction for self-occupied home-loan interest, so your real cost is the full 8.5%. The old vs new regime guide shows which regime suits you.

Before you prepay, keep six months of expenses in an emergency fund (money paid into a loan is hard to get back), clear costlier debt such as credit cards and personal loans first, and keep your health and term insurance in place.

Home-loan basics people ask about

• Prepayment charges: on floating-rate loans to individuals for non-business purposes, which covers most home loans, lenders can't charge for part or full prepayment. The RBI's Pre-payment Charges on Loans Directions, 2025 restate this for loans sanctioned or renewed from 1 January 2026, with no lock-in period. Fixed-rate loans can carry a charge, which must be shown in the sanction letter and Key Facts Statement.
• Reducing balance versus flat rate: bank EMIs are calculated on the reducing balance. Some consumer loans quote a "flat" rate, which is far costlier than it sounds: ₹1 lakh at 10% flat for 3 years means ₹30,000 of interest and an EMI of ₹3,611.11, the same as about 17.9% on a reducing balance. At a true 10%, the calculator shows an EMI of ₹3,226.72 and interest of ₹16,161.87.
• When rates rise: on floating-rate loans many lenders keep the EMI and lengthen the tenure. Check your annual statement, and ask whether you can raise the EMI instead so the loan doesn't stretch out.
• Other loans: car and personal loans use the same formula. Try the car loan calculator for vehicle offers.

This is general information to help you compare options, not financial or tax advice; check your loan agreement and speak to your lender before prepaying.

Frequently asked questions

Should I reduce my EMI or my tenure after a prepayment?

Reducing the tenure saves the most interest: ₹14.57 lakh against ₹4.78 lakh in our ₹50 lakh example. Reduce the EMI only if you need the monthly breathing room.

How much does one extra EMI a year save?

On a ₹50 lakh loan at 8.5% for 20 years, paying one extra EMI at the end of each year (and keeping the EMI unchanged) ends the loan after 201 months instead of 240 and saves about ₹10.29 lakh of interest.

Will prepaying reduce my home-loan tax benefit?

Only in the old regime, and only once your yearly interest falls below the ₹2 lakh deduction limit. Early in a large loan, prepaying mainly cuts interest that gets no deduction anyway.

Can my bank charge a penalty for prepaying a home loan?

Not on a floating-rate home loan taken by an individual for non-business purposes. Fixed-rate loans may have a charge; it must be disclosed in your sanction letter and Key Facts Statement.

How do I find my outstanding loan balance?

Download the loan statement or amortisation schedule from your lender's net banking or app. It shows the principal outstanding after each EMI, which is the amount to enter in the calculator.

Is EMI calculated on a flat rate or reducing balance?

Bank home, car and personal loans use the reducing balance, as in the formula above. If a lender quotes a flat rate, convert it before comparing: 10% flat over 3 years is roughly 17.9% on a reducing balance.

Sources: Reserve Bank of India (Pre-payment Charges on Loans) Directions, 2025 (2 July 2025); Income-tax Act, 2025 (section 22 and section 123 with Schedule XV); mutual fund tax rates for Tax Year 2026-27.