How Banks Calculate Home Loan EMI: The Formula Explained

A home loan of 50 lakh at 8.5 percent interest for 20 years charges a total interest of 54,13,879 over the full tenure. That is more than the principal itself. The EMI stays the same at 43,391 every month, but the split between interest and principal changes dramatically over those 240 payments.

Quick Answer

The EMI formula is P times r times (1 plus r) raised to n, divided by ((1 plus r) raised to n minus 1). P is principal, r is monthly interest rate (annual divided by 12), n is tenure in months. Banks compound monthly, not yearly, which is why your EMI is higher than a simple interest calculation would suggest. The first EMI is mostly interest because the outstanding principal is at its peak.

The Core Formula

Every bank in India uses the same equated monthly installment formula. There is no secret version reserved for preferred customers.

EMI = P x r x (1 + r)^n / ((1 + r)^n - 1)

Where:
P = Loan principal (e.g. 50,00,000)
r = Monthly interest rate = annual rate / 12 / 100
n = Number of monthly installments = years x 12

For a 50 lakh loan at 8.5 percent annual interest over 20 years:

• P = 50,00,000
• r = 8.5 / 12 / 100 = 0.00708333
• n = 20 x 12 = 240
• (1 + r)^n = 1.00708333^240 = 5.41335
• EMI = 50,00,000 x 0.00708333 x 5.41335 / (5.41335 - 1)
• EMI = 50,00,000 x 0.00708333 x 5.41335 / 4.41335
• EMI = 1,91,701 / 4.41335 = 43,391

Try different numbers on our EMI calculator to see how sensitive the EMI is to each input.

Why Banks Compound Monthly, Not Annually

If a bank quoted 8.5 percent and charged interest once at the end of the year, your effective cost would be exactly 8.5 percent. Because banks compute interest every month on the outstanding balance, the true annual cost is slightly higher.

The effective annual rate (EAR) for an 8.5 percent monthly compounded rate:

EAR = (1 + r)^12 - 1
EAR = (1 + 0.00708333)^12 - 1
EAR = 1.08839 - 1 = 0.08839 = 8.839%

So 8.5 percent quoted becomes 8.839 percent effective. Over 20 years, this difference compounds into lakhs of rupees.

Amortization Table: Month 1 Through Month 12

Here is the first year of a 50 lakh, 8.5 percent, 20 year home loan. Interest for each month equals outstanding principal times 0.00708333. Principal portion equals EMI minus interest. Closing balance equals opening balance minus principal portion.

Month	Opening	EMI	Interest	Principal	Closing
1	50,00,000	43,391	35,417	7,974	49,92,026
2	49,92,026	43,391	35,361	8,030	49,83,996
3	49,83,996	43,391	35,304	8,087	49,75,909
4	49,75,909	43,391	35,247	8,144	49,67,765
5	49,67,765	43,391	35,189	8,202	49,59,563
6	49,59,563	43,391	35,131	8,260	49,51,303
7	49,51,303	43,391	35,072	8,319	49,42,984
8	49,42,984	43,391	35,013	8,378	49,34,606
9	49,34,606	43,391	34,954	8,437	49,26,169
10	49,26,169	43,391	34,894	8,497	49,17,672
11	49,17,672	43,391	34,834	8,557	49,09,115
12	49,09,115	43,391	34,773	8,618	49,00,497

After 12 EMIs totalling 5,20,692, you have paid 4,20,195 as interest and only 1,00,497 has gone toward reducing your principal. That is 80.7 percent of your first year outgo going to the bank as interest.

Year-End Balances Across the Full Tenure

The crossover month, where principal portion exceeds interest portion, is month 144 for this loan. Before that, interest dominates. After, principal takes over.

End of Year	Outstanding Principal	Interest Paid to Date	Principal Paid to Date
1	49,00,497	4,20,195	99,503
5	44,43,000	20,46,460	5,57,000
10	36,44,000	39,43,920	13,56,000
15	23,99,000	54,16,380	26,01,000
20	0	54,13,879	50,00,000

Total interest over 20 years: 54,13,879. Total repayment: 1,04,13,879. You pay roughly 2.08 times the principal over the loan tenure.

Floating Rate: MCLR and EBLR Explained

Indian banks price floating rate home loans using one of two internal benchmarks.

MCLR (Marginal Cost of Funds Based Lending Rate)

Introduced by RBI in April 2016 via its Master Direction on Interest Rate on Advances, MCLR is computed monthly by each bank based on four components: marginal cost of funds, negative carry on cash reserve ratio, operating costs, and tenor premium. The home loan rate equals 1 year MCLR plus a bank spread, typically between 10 and 50 basis points.

EBLR (External Benchmark Lending Rate)

Per RBI Circular RBI/2019-20/160 dated 4 September 2019, all new floating rate retail loans sanctioned after 1 October 2019 must be linked to an external benchmark. The approved benchmarks are the RBI repo rate, the 3 month Treasury bill yield, the 6 month Treasury bill yield, or any other benchmark published by Financial Benchmarks India.

Most banks picked the repo rate. A typical home loan rate today: Repo rate (6.25 percent as of April 2026) plus bank spread (2.25 percent) equals 8.50 percent. When RBI cuts repo by 25 basis points, your rate drops to 8.25 percent automatically at the next reset date, usually every 3 months.

Prepayment Math: Why Timing Matters

A prepayment of 5 lakh made at different points in the loan tenure has very different impacts on total interest saved.

When Prepayment Made	Interest Saved	Tenure Reduced By
End of year 2	11,42,000	39 months
End of year 5	8,61,000	32 months
End of year 10	4,72,000	20 months
End of year 15	1,68,000	9 months

The earlier you prepay, the longer the remaining balance would have accrued interest, so the saving is larger. Prepaying in year 15 is mathematically much weaker than the same amount prepaid in year 2.

Per RBI circular dated 5 May 2014, banks cannot charge any foreclosure or prepayment fee on floating rate home loans taken by individual borrowers. Fixed rate loans may carry prepayment charges, disclosed in your sanction letter.

Run your own numbers on the loan prepayment calculator to see tenure reduction versus EMI reduction scenarios.

Fixed vs Floating: The Trade Off

Fixed rate home loans keep your EMI constant for the full tenure. Rates today run 50 to 150 basis points above floating rates. The premium is the price of certainty.

Floating rate loans move with the external benchmark. Over a 20 year period, rates typically cycle through 2 or 3 full up-and-down swings. Historical data from RBI shows average home loan rates ranged between 7.1 percent (2021 low) and 10.5 percent (2013 high) over the past 15 years.

A hybrid option some banks offer: fixed for the first 3 to 5 years, floating afterward. The fixed period protects you during the early high-interest years, and the floating period captures any subsequent rate cuts.

The Processing Fee Trap

Banks advertise 8.5 percent interest but add a processing fee of 0.25 to 1 percent of the loan amount, often capped at 25,000 or 50,000. On a 50 lakh loan at 0.5 percent, the fee is 25,000.

The effective interest rate including processing fee is slightly higher than the quoted rate. For a 50 lakh loan at 8.5 percent with a 25,000 processing fee paid upfront, the true annual cost is approximately 8.53 percent when amortized over 20 years. Small on paper, meaningful in absolute terms: 1,50,000 extra over the full tenure.

Tax Treatment of Interest Paid

Under Section 24(b) of the Income Tax Act, interest paid on a home loan for a self-occupied property is deductible up to 2 lakh per year in the old tax regime. Under Section 80C, principal repayment is deductible up to 1.5 lakh per year (shared with other 80C items like PPF and ELSS).

For a let-out property, the full interest paid is deductible against rental income, though a loss set-off cap of 2 lakh against other income applies per year. The remaining loss carries forward for 8 years.

Under the new tax regime introduced by Section 115BAC, these deductions are not available for self-occupied property. The let-out property interest deduction continues.

Disclaimer

This article is informational only. The author is not a Chartered Accountant or SEBI registered advisor. Home loan decisions depend on your income, credit profile, and long term financial goals. Consult a Chartered Accountant or licensed mortgage advisor before signing a sanction letter.

Byline: By Aniket Nigam. Verified 2026-04-15 against RBI Circular RBI/2019-20/160 (EBLR), RBI Master Direction on Interest Rate on Advances (MCLR), and the Income Tax Act sections 24(b), 80C, and 115BAC. Methodology: amortization table computed from first principles using the standard EMI formula at monthly compounding.