How to Calculate Your Loan EMI and Total Interest
An Equated Monthly Instalment (EMI) is the fixed amount you pay every month until a loan is fully repaid. Understanding how EMI is calculated — and how much of each payment goes to interest versus principal — helps you compare loan offers and avoid expensive surprises.
The EMI Formula
The standard EMI formula used by banks worldwide is:
Where:
- P = Principal loan amount
- r = Monthly interest rate (annual rate ÷ 12 ÷ 100)
- n = Total number of monthly payments (loan tenure in months)
Example: A ₹5,00,000 loan at 10% annual interest for 3 years (36 months):
- r = 10 / 12 / 100 = 0.00833
- n = 36
- EMI = 5,00,000 × 0.00833 × (1.00833)36 / ((1.00833)36 − 1) ≈ ₹16,134 per month
Total paid = ₹16,134 × 36 = ₹5,80,824. Total interest paid = ₹5,80,824 − ₹5,00,000 = ₹80,824.
How Principal and Interest Split Each Month
Your EMI amount stays the same every month, but what goes toward interest and what reduces the principal changes month by month. In the early months, most of your payment goes to interest. As the principal decreases, the interest component falls and more money goes toward repaying the actual loan.
This is called an amortisation schedule. Knowing this is important because:
- If you make a prepayment early in the loan tenure, you save much more interest than a prepayment made near the end.
- Refinancing at a lower interest rate early in the loan gives you the biggest benefit.
- The total interest paid is highest for loans with long tenures, not just high principal.
What Affects Your EMI?
Three variables drive your EMI amount:
- Loan amount (principal): Borrow less and your EMI falls proportionally.
- Interest rate: Even a 0.5% difference on a large loan can cost tens of thousands over the full tenure. Always compare the Annual Percentage Rate (APR), not just the nominal rate.
- Loan tenure: A longer tenure means smaller monthly payments but more total interest paid. A shorter tenure means higher EMIs but lower total cost.
Home Loan vs Personal Loan vs Car Loan — Key Differences
Different loan types carry different rates and structures:
- Home loans typically have the lowest interest rates (6–9% in most markets) because the property acts as collateral. Tenures can reach 30 years, making them the most sensitive to rate changes.
- Car loans usually run 1–7 years at 7–12%. The vehicle depreciates, so the loan balance can exceed the car's value if the tenure is long and the down payment is small.
- Personal loans are unsecured and carry the highest rates, often 12–24%. Keep the tenure short and borrow only what you can repay within 2–3 years.
Common Mistakes to Avoid
- Focusing only on EMI, not total cost. A bank offering ₹500 lower monthly payment could still cost you ₹1,00,000 more over the full tenure due to a longer loan term.
- Ignoring processing fees and prepayment penalties. Some lenders charge 1–3% of the loan amount as a processing fee, and others penalise early repayment. These costs belong in your comparison.
- Borrowing at the upper limit of affordability. Financial advisors generally suggest keeping total loan EMIs below 40–50% of your take-home income. Unexpected expenses can make servicing debt at the edge of your budget very stressful.
Use the Free EMI Calculator
Rather than doing this arithmetic manually, the SantoshTec EMI Calculator lets you enter the loan amount, annual interest rate, and tenure in months or years. It instantly shows your monthly EMI, total amount payable, and total interest charged so you can quickly compare multiple loan scenarios before committing.
Try these free tools mentioned in this article: