1. The tenure formula, explained
The EMI formula rearranges to solve for n (number of months):
n = −log(1 − (P × r) / EMI) ÷ log(1 + r)
Where:
- P = principal, the amount borrowed
- r = monthly interest rate (annual rate ÷ 12 ÷ 100)
- EMI = your fixed monthly payment
The formula only works if your payment is greater than the monthly interest
on the original loan (P × r). If it's less, the loan will never be repaid.
We flag that case in the calculator.
2. Why small payment changes have a huge effect
On a ₹10 lakh loan at 9%, paying ₹20,758/month clears it in 5 years.
Increase that to ₹25,000/month and you pay it off in about 3 years 11 months.
That extra ₹4,242/month saves over ₹1.2 lakh in interest.
⚠️ The relationship is non-linear. Doubling your payment doesn't halve the tenure — it reduces it far more dramatically in the early years.
3. Minimum payment threshold
For a ₹10 lakh loan at 9%, the monthly interest alone is ₹7,500.
Any payment below this never touches the principal — the balance actually
grows if you pay less (negative amortization). Most lenders won't allow this,
but it's the reason small payments can stretch a loan for decades.
4. How interest rate changes affect tenure
If you keep the same monthly payment but interest rates rise, the tenure
extends. At 9% with ₹20,758/month, you pay off ₹10 lakh in 5 years. At 12%,
the same payment takes about 5 years 10 months. At 15%, nearly 7 years.
This is why floating-rate borrowers should review their payments when
rates move — increasing the payment can keep the tenure on track.
5. Rounding and the final payment
The formula gives a fractional number of months. We round up and
recalculate the final payment to clear the remaining balance.
For example, if the formula says 58.3 months, you'll make 58 full payments
and a smaller 59th payment.
This is standard practice with most lenders — your last EMI is often
slightly lower (or occasionally higher) than the others.
6. Comparing payment sizes
On a ₹10 lakh, 9% loan:
- ₹15,000/month: never repaid (below interest threshold of ₹7,500 + principal)
- ₹18,000/month: ~7 years 2 months · total interest ~₹5.5 lakh
- ₹20,758/month: exactly 5 years · total interest ~₹2.45 lakh
- ₹25,000/month: ~3 years 11 months · total interest ~₹1.68 lakh
- ₹35,000/month: ~2 years 7 months · total interest ~₹1.06 lakh
Every additional rupee above the minimum shortens the loan and cuts total interest.
7. Common mistakes to avoid
- Paying too little each month. If your payment barely covers interest, the loan never ends.
- Ignoring rate changes on floating loans. When rates rise, your tenure extends unless you increase payments.
- Not checking the final payment. It can differ from your regular EMI — make sure you know the exact amount.
- Forgetting fees. Processing fees and insurance add to the effective cost but don't reduce the tenure.
8. How to use this calculator
- Enter your loan amount (principal).
- Set the annual interest rate your lender has quoted.
- Enter the monthly payment you can comfortably afford.
- See the calculated tenure, total interest, and full schedule.
- Adjust the payment slider to compare scenarios.
- Use the quick preset buttons for common payment levels.
9. Final thoughts
Tenure is the outcome, not the input. By focusing on what you can pay each month,
you take control of the loan term — and can see directly how paying a little
more each month translates into months (or years) shaved off your debt.