Calculate the total interest you'll pay over a loan's entire tenure.
First, the EMI is worked out using the standard formula. This is multiplied by the number of months to get the total amount paid. The original loan amount is then subtracted from that, to give the total interest.
Total interest: (EMI × months) − Principal
The loan interest calculator focuses on one number: the total interest you will pay over the full life of a reducing-balance loan. It computes the EMI from the loan amount, rate and tenure, multiplies it by the number of months, and subtracts the amount borrowed. What is left is the lender's income from your loan.
Borrowers often look only at the EMI, but the total interest is the true price of borrowing. Seeing that a ₹7.5 lakh loan costs well over a lakh in interest, or that a home loan's interest can approach or exceed the amount borrowed, changes how people choose between tenures and whether they prepay. The calculator is a quick way to put a rupee figure on the cost of a loan before you commit to it.
1. Write down the loan amount P, the annual rate and the tenure n in months.
2. Convert to a monthly rate r = annual rate ÷ 12 ÷ 100.
3. Compute the EMI = P × r × (1 + r)ⁿ ÷ ((1 + r)ⁿ − 1).
4. Compute the total paid = EMI × n.
5. Total interest = total paid − P.
6. Divide total interest by P to see interest as a share of the loan.
A common guess is that a 10% loan over 5 years costs 50% of the principal in interest. That would be true only for a flat rate. On a reducing balance, interest in each month is charged only on what is still owed, and the balance falls steadily to zero. On average, the balance outstanding is a little more than half the original amount, so total interest is usually a little more than half of P × rate × years. The exact amount comes from the EMI formula, which is what this calculator uses.
Total interest rises faster than the tenure. Doubling a loan's tenure at the same rate lowers the EMI, but the balance stays high for much longer, so total interest more than doubles. For long home loans at typical rates, total interest over 20 years is often about equal to the amount borrowed, and over 30 years it can be well above it. Shortening the tenure, even by a few years, can cut total interest by a large amount while raising the EMI only modestly.
The figure assumes a fixed rate and that every EMI is paid on time for the full tenure. It does not include processing fees, insurance, documentation charges or penalties, and it does not reflect prepayments, which reduce interest. For a floating-rate loan, it is only an estimate at today's rate. It also ignores the time value of money: interest paid in year 15 is not worth the same as interest paid in year one, though it counts equally in this total.
Tanvi is considering a ₹7,50,000 loan at 11% a year for 48 months to renovate her parents' house.
Write the formula: EMI = P × r × (1+r)ⁿ ÷ ((1+r)ⁿ − 1)
Convert the annual rate to a monthly rate: r = 11% ÷ 12 ÷ 100 = 0.00916667
Number of instalments: n = 48 months
Substitute your values: EMI = 750000 × 0.009167 × (1+0.009167)^48 ÷ ((1+0.009167)^48 − 1)
Monthly EMI: EMI
Total paid over the full tenure: 19384.14 × 48
Total interest: 930438.81 − 750000
Answer: Total interest payable ₹1,80,439; Monthly EMI ₹19,384; Total payment ₹9,30,439
Estimating interest as principal × rate × years, which describes a flat-rate loan.
Looking at interest for one year and assuming it stays the same every year.
Forgetting that fees and insurance add to the cost of the loan beyond interest.
Comparing total interest across loans of different amounts without looking at it as a share of principal.
Seeing the full cost of a loan before signing.
Comparing total interest for different tenures on the same loan.
Measuring how much interest a prepayment plan could avoid.
Explaining the cost of borrowing in a household budget discussion.
Is this the interest for one year or the whole loan?
This is for the whole loan, not just one year. It is the total interest paid across every EMI, from the start to the very end.