A loan offer usually highlights the monthly payment because it looks small and manageable. The number that really matters is how much extra you pay over the whole loan: the total interest. This guide shows how to calculate total interest on a loan, why it grows so quickly with time, and how to compare offers with our Loan Calculator.
The simple formula
Total interest = monthly payment × number of payments − loan amount
Example: Rs 2,500,000 for 5 years at 15%. The monthly payment is about Rs 59,475.
- Total paid: 59,475 × 60 = Rs 3,568,500
- Total interest: 3,568,500 − 2,500,000 = Rs 1,068,500
So you pay back about 1.43 times what you borrowed.
How rate and tenure change the total
Same Rs 2,500,000 loan:
| Rate | 3 years | 5 years | 10 years |
|---|---|---|---|
| 12% | Rs 489,000 | Rs 836,700 | Rs 1,804,000 |
| 15% | Rs 620,000 | Rs 1,068,500 | Rs 2,340,000 |
| 18% | Rs 753,000 | Rs 1,309,000 | Rs 2,906,000 |
Doubling the tenure from 5 to 10 years more than doubles the interest. A three-point rate increase on a 10-year loan adds over a million rupees.
Simple interest vs reducing balance
Some informal lenders quote simple or flat interest, charging the full rate on the original amount every year. That costs far more than reducing-balance interest at the same quoted rate. Our article flat vs reducing balance shows the difference clearly.
Fees count too
Processing fees, insurance and documentation charges are part of the real cost even though they are not “interest”. Add them to the total interest when comparing offers. A loan with a slightly higher rate but no fees can be cheaper overall.
A comparison checklist
- Enter each offer’s amount, rate and tenure in the loan calculator.
- Note the total interest.
- Add all fees.
- Choose the offer with the lowest total cost that has a monthly payment you can afford.
Paying less interest
- Borrow less by saving a bigger down payment.
- Choose the shortest tenure you can manage.
- Prepay when you can.
- Negotiate the spread over KIBOR.
More ideas are in ways to reduce your EMI. For a simple percentage of how much extra you pay, use the Percentage Calculator.
See where the interest goes
Total interest is the sum of the interest part of every payment. To see how that interest is spread over the months and years, open the schedule in the calculator and read what an amortization schedule is. If you are weighing a car or home loan specifically, the EMI Calculator is quicker for the monthly figure.
Frequently asked questions
How do I calculate total interest on a loan?
Multiply the monthly payment by the number of payments and subtract the loan amount.
Does a longer loan always cost more interest?
Yes, at the same rate, because you pay interest for more months on a slower-falling balance.
Should I include fees when comparing loans?
Yes. Fees are part of the real cost of borrowing.