Mastering the Trop Maturity Payout Formula for Accurate EMI Calculations
The math behind EMI calculation and how the interest-to-principal split changes over the loan tenure.
By Hannav Editorial
Updated 3 Aug 2026
6 Min Read
EMI is the single figure that keeps your bank account, tax return and future savings on a tight leash. When you ask a lender for a loan, the bank will give you an EMI that is calculated from three inputs: the principal amount, the annual interest rate and the repayment tenure. The same formula is used for home loans, personal loans, auto loans and even for business working‑capital facilities. Understanding how the formula works, how the interest and principal portions shift over time, and how pre‑payments can shave years off the tenure will help you negotiate a better deal and keep more money in your pocket.
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1. What drives the size of my EMI?
Factor
Typical lender requirement
Impact on the EMI
Principal
₹10 lakh – ₹1 crore
Directly proportional
Annual interest rate
7 %–12 % (fixed or floating)
Exponential effect over long tenures
Tenure
5 – 30 years
Longer tenure → lower EMI but higher total interest
Processing fee & insurance
0.5 %–2 % of principal
Adds to the effective cost
Credit score
≥ 750 preferred
May unlock lower rates
Income & FOIR
Salary/ITR vs. EMI
Determines maximum permissible EMI
The bank’s risk assessment is reflected in the interest rate and the maximum EMI it will allow. A 0.25 % higher rate on a ₹40 lakh home loan can cost you ₹2–3 lakh more in interest over 20 years. Therefore, before you accept an offer, compare the total interest paid and not just the headline EMI.
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2. How is the EMI calculated?
The reducing‑balance method is used by almost all Indian banks. The formula is:
So the borrower will pay ₹9,200 every month for 20 years.
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3. What does the amortisation schedule look like over 20 years?
An amortisation table shows how each EMI is split into interest and principal, and how the outstanding balance shrinks.
Month
EMI (₹)
Interest (₹)
Principal (₹)
Outstanding (₹)
1
9,200
7,500
1,700
998,300
2
9,200
7,485
1,715
996,585
3
9,200
7,470
1,730
994,855
…
…
…
…
…
240
9,200
70
9,130
0
Key take‑aways
The first 12–18 months are almost entirely interest.
By the 10th year, the principal portion exceeds the interest portion.
The outstanding balance falls from ₹10 lakh to ₹0 over 240 payments.
The table also helps you see the cumulative interest paid:
Tenure
Total interest (₹)
10 yrs
1,20,000
15 yrs
1,80,000
20 yrs
2,40,000
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4. How does tenure versus interest rate affect total interest paid?
Tenure
Rate 8 %
Rate 9 %
Rate 10 %
10 yrs
₹1,20,000
₹1,32,000
₹1,44,000
15 yrs
₹1,80,000
₹1,98,000
₹2,16,000
20 yrs
₹2,40,000
₹2,64,000
₹2,88,000
Illustration
A borrower taking a ₹10 lakh loan at 9 % for 20 years will pay ₹2,64,000 in interest. If the same loan is taken at 8 % for 15 years, the interest drops to ₹1,98,000 – a saving of ₹66,000, even though the monthly EMI rises from ₹9,200 to ₹9,900.
Take‑away Shorter tenure and lower rate together reduce the total cost dramatically. If you can afford a higher EMI, it pays off in the long run.
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5. How can I use an amortisation table to plan pre‑payments?
Pre‑paying a lump sum reduces the outstanding balance, which in turn reduces future interest and can shorten the tenure.
Scenario
Original loan: ₹10 lakh, 9 % p.a., 20 years, EMI ₹9,200.
After 5 years (60 payments), outstanding balance ≈ ₹7,50,000.
Lump‑sum pre‑payment: ₹2 lakh.
Effect
Result
New outstanding
₹5,50,000
New tenure (same EMI)
12 years 4 months
Total interest saved
₹45,000
The borrower can either keep the same EMI and finish the loan 7 years earlier, or reduce the EMI to ₹7,800 and finish in 20 years while saving ₹45,000 in interest.
Tip Check the lender’s pre‑payment policy. Some banks charge a 2 % fee on the pre‑payment amount; factor that into the calculation.
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6. Common mistakes that inflate the cost of a loan
Mistake
Why it hurts
Correct approach
Using the headline interest rate without adding processing fee
Underestimates effective cost
Add processing fee (e.g., 1 % of principal) to the rate
Ignoring the tax benefit on home loan interest
Misses ₹2–3 lakh tax saving
Compute tax credit (up to ₹2 lakh under Section 24(b))
Choosing the longest tenure to lower EMI
Increases total interest
Compare total interest for 10, 15, 20‑year options
Pre‑paying without checking penalty
May pay extra fee
Verify pre‑payment penalty (often 1–2 % of the amount)
Example of a miscalculation A borrower sees a 9 % rate, 20‑year tenure and calculates EMI ₹9,200. The bank’s processing fee is 1 % of ₹10 lakh = ₹10,000. Adding this fee to the rate (9 % + 1 % = 10 %) raises the EMI to ₹9,800 and total interest to ₹2,88,000 instead of ₹2,64,000. The borrower saves ₹24,000 by accounting for the fee upfront.
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7. Real‑world example: textile shop owner in Coimbatore
Background
Owner, Ravi, runs a small textile shop with an annual GST turnover of ₹18 lakh.
He needs ₹10 lakh to purchase new looms and upgrade machinery.
He has ₹2 lakh in cash to act as a down‑payment, improving his loan‑to‑value ratio.
Loan options
Lender
Product
Tenure
Rate (fixed)
Processing fee
EMI (₹)
Total interest (₹)
SIDBI
Term loan
7 yrs
8.5 %
0.5 %
1,42,000
1,12,000
Mudra Shishu
Working‑capital
3 yrs
9.5 %
0.5 %
3,00,000
1,20,000
HDFC Bank
Personal loan
5 yrs
10 %
1 %
1,80,000
1,50,000
Analysis
The SIDBI term loan offers the lowest total interest because of the longer tenure and lower rate.
The Mudra Shishu product is attractive for a short‑term working‑capital gap but has a higher rate.
The personal loan from HDFC Bank is the most expensive overall.
Decision Ravi chooses the SIDBI term loan, pays ₹2 lakh down‑payment, and takes ₹8 lakh. His EMI of ₹1,42,000 is affordable given his monthly turnover, and the total interest of ₹1,12,000 is the lowest among the options.
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8. Final thoughts
EMI calculation is not a mystery; it is a straightforward application of a reducing‑balance formula. What matters most is how you use the numbers:
1. Compare total interest, not just EMI. 2. Shorten tenure or negotiate a lower rate to cut costs. 3. Plan pre‑payments strategically to shave years off the loan. 4. Factor in processing fees, insurance and tax benefits.
By treating the EMI as a tool rather than a fixed obligation, you can keep your finances lean and your future savings intact.
Disclaimer: The information provided in this article is for educational and informational purposes only. It does not constitute financial, investment, legal, or tax advice. Readers should consult a SEBI-registered investment advisor or other qualified professional before making any investment decisions.
Frequently Asked Questions
What is How Loan EMI Is Calculated?
The math behind EMI calculation and how the interest-to-principal split changes over the loan tenure.
Are rates and tax figures on this page guaranteed?
No. Any rates, slabs, or scheme limits are indicative and FY-sensitive. Confirm on official sources (ITD, RBI, SEBI, EPFO, India Post, issuer) and consult a CA or licensed adviser for your situation.
Is this personalised financial advice?
No. Hannav content is educational. Loan sanction, tax filing, and investment decisions require your documents and professional advice where needed.