EMI Formula Explained – How to Calculate Equated Monthly Instalment (2026)
If you are planning to take a home loan, a car loan, or a personal loan, the first number you want to know is your monthly EMI. EMI stands for Equated Monthly Instalment. It is the fixed amount you pay every month to the bank or financial institution until the loan is fully repaid. Understanding how EMI is calculated helps you plan your budget, compare loan offers, and avoid surprises. In this guide, I will explain the EMI formula, break it down with examples, show you an amortization table, and give you a free EMI calculator link.
The Standard EMI Formula
The mathematical formula used by all banks and financial institutions is the same. It is based on the concept of reducing balance. Here it is:
Where:
- P = Principal loan amount (the amount you borrow)
- r = Monthly interest rate (annual interest rate divided by 12, then divided by 100 if percentage)
- n = Loan tenure in months (number of monthly instalments)
Note: If your annual interest rate is given as a percentage, say 9% per annum, then r = (9 / 12) / 100 = 0.09 / 12 = 0.0075 per month.
Step-by-Step Example – Home Loan EMI Calculation
Let us take a real example. Suppose you take a home loan of 50 lakh rupees (5,000,000 INR) at an annual interest rate of 8.5% for 20 years (240 months).
Annual rate = 8.5% → monthly r = (8.5 / 12) / 100 = 0.70833% = 0.00708333
n = 20 × 12 = 240 months
EMI = 5,000,000 × 0.00708333 × (1.00708333)^240 / ((1.00708333)^240 – 1)
Using a calculator, (1.00708333)^240 ≈ 5.384
EMI = 5,000,000 × 0.00708333 × 5.384 / (5.384 – 1)
= 5,000,000 × 0.03814 / 4.384 ≈ 190,700 / 4.384 ≈ 43,488 rupees per month.
So your monthly EMI would be approximately 43,488 rupees. Over 20 years, you will pay a total of 43,488 × 240 = 10,437,120 rupees. That means total interest paid is 10,437,120 – 5,000,000 = 5,437,120 rupees – almost the same as the principal itself.
Car Loan Example – Shorter Tenure
For a car loan, tenures are shorter. Example: Car loan of 8 lakh rupees (800,000 INR) at 10% annual interest for 5 years (60 months).
Monthly r = (10/12)/100 = 0.83333% = 0.0083333
n = 60
(1.0083333)^60 ≈ 1.645
EMI = 800,000 × 0.0083333 × 1.645 / (1.645 – 1)
= 800,000 × 0.013708 / 0.645 ≈ 10,966 / 0.645 ≈ 17,000 rupees per month (approx).
Total repayment = 17,000 × 60 = 1,020,000. Interest = 220,000 rupees.
What is Amortization? (Principal vs Interest)
In the initial months of your loan, a larger portion of your EMI goes toward paying the interest. Only a small part reduces the principal. As time passes, the interest portion decreases and the principal portion increases. This is called loan amortization.
Here is an amortization table for the first few months of the home loan example (50 lakh, 8.5%, 240 months).
| Month | EMI (Rs) | Interest Component (Rs) | Principal Component (Rs) | Remaining Principal (Rs) |
|---|---|---|---|---|
| 1 | 43,488 | 35,417 | 8,071 | 49,91,929 |
| 2 | 43,488 | 35,363 | 8,125 | 49,83,804 |
| 3 | 43,488 | 35,305 | 8,183 | 49,75,621 |
| … (after 120 months) | ||||
| 120 | 43,488 | 25,720 | 17,768 | 33,42,000 (approx) |
You can see that in the first month, out of 43,488 rupees, 35,417 is just interest. Only 8,071 goes toward reducing your principal. This is why pre-paying early saves a lot of interest.
Factors That Affect Your EMI
- Principal amount (P): Higher loan amount means higher EMI. If you increase the down payment, EMI decreases.
- Interest rate (r): Even a small change in interest rate can significantly affect EMI. For a 50 lakh loan over 20 years, an increase from 8.5% to 9% raises EMI by about 1,500 rupees per month.
- Tenure (n): Longer tenure reduces EMI but increases total interest paid. Shorter tenure increases EMI but saves interest. Example: same 50 lakh at 8.5% – for 15 years (180 months) EMI is about 49,000 rupees, but total interest is much lower.
How to Reduce Your EMI or Total Interest
Here are practical strategies:
- Increase down payment: Borrow less principal. That directly lowers EMI.
- Choose a longer tenure: EMI becomes smaller, but you will pay more interest over time. Only do this if your monthly cash flow is tight.
- Pre-pay part of the loan: Any lump sum payment you make (like annual bonus) reduces principal. The bank will either reduce your EMI or reduce the tenure. Both save interest.
- Negotiate a lower interest rate: Especially for home loans, if you have a good credit score, you can ask for a rate reduction or transfer the loan to another bank with lower rate.
Common Mistakes People Make
- Focusing only on EMI and ignoring the total interest payable. A lower EMI with very long tenure may cost double the principal in interest.
- Not checking whether the bank uses reducing balance method (which is standard) or flat rate method (rare, but costly). In flat rate, interest is calculated on original principal for entire tenure – avoid that.
- Ignoring processing fees and other charges. A loan with slightly higher EMI but lower processing fee may be better.
- Not comparing EMI at different tenures before taking the loan.
Use Our Free EMI Calculator
Manually calculating EMI using the formula is possible but tedious, especially for long tenures. We have built an EMI calculator on this site. Just enter principal, annual interest rate, and tenure in years or months. It will instantly give you the monthly EMI, total interest payable, and total payment. You can also see an amortization schedule.
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