Why your bank shows a different EMI than online calculators

You ran the numbers on an online EMI calculator. It said ₹43,391. The bank's sanction letter says ₹43,408. Why the ₹17 difference, and which one is right? Both, actually. The discrepancy is real but small, and understanding why it exists tells you something useful about how loan interest actually works.

The standard EMI formula

Every online calculator (this one included) uses the same formula:

EMI = P × r × (1+r)^n / ((1+r)^n - 1)

where P is principal, r is monthly interest rate (annual ÷ 12), and n is the number of months.

This formula assumes that interest compounds monthly and that the time between EMI payments is exactly one month. Both assumptions are simplifications.

What banks actually do

Indian banks calculate interest using one of several day-count conventions. The most common is "actual/365" — interest is computed using the actual number of days between payments, divided by 365.

In months with 28, 29, 30, or 31 days, the interest amount varies slightly. February's interest is roughly 7-10% less than July's. The bank's amortization schedule reflects this; the calculator's monthly rate of (annual/12) does not.

The accumulated difference

Over the life of a 20-year loan, the day-count difference accumulates to a few hundred rupees. The EMI itself is rounded to whole rupees, and most banks round up by ₹1-50.

Worked example for ₹50L, 8.5%, 20 years:

• Calculator EMI (formula): ₹43,391.16
• Bank EMI (actual/365 + rounding): typically ₹43,390 to ₹43,420
• Difference per month: ₹1 to ₹30
• Difference per year: ₹12 to ₹360
• Difference over loan life: ₹240 to ₹7,200

This is real money but not life-changing. The difference is roughly 0.01-0.05% of the loan amount over its full term.

Other reasons for discrepancy

1. Processing fees and charges

If the bank deducts processing fees from the disbursed amount (rather than separately), the actual loan amount is slightly less than the sanctioned amount. EMI computed on actual disbursed amount differs from EMI computed on sanctioned amount.

2. Insurance bundling

Some banks bundle a small term insurance or home insurance into the loan. The added amount changes your EMI by a few hundred rupees. Always ask whether the EMI you're being quoted includes any insurance premium.

3. First-month interest

If your loan disburses on the 15th of a month, your first month's interest is for 15 days, not 30. Some banks adjust the first month's EMI; others charge a separate "broken period interest" upfront. The downstream EMI may not match calculator output exactly.

4. Floating-rate reset dates

If your rate is linked to EBLR and resets quarterly, your EMI may change every 3 months depending on RBI repo rate movements. The calculator gives you the EMI at today's rate; the bank gives you a moving target.

5. GST on processing fee

The 18% GST on processing fee is sometimes added to the loan amount rather than collected upfront, changing the effective principal.

When the difference matters

For 99% of borrowers, the calculator output is accurate enough. Use it to plan your budget, compare loan options, and negotiate with banks. Don't sweat the ₹20-100 difference.

The difference matters when:

• You're comparing two banks with very similar rates and the day-count convention differs (some banks use 360-day year)
• You're prepaying and the bank's interest calculation method affects how much principal reduction you get
• You're computing exact tax deductions and need the actual interest paid each financial year

In all three cases, use the bank's amortization schedule (they'll provide it on request) rather than the calculator output.

What this calculator does

indiaemi.com uses the standard EMI formula — same as every other calculator. The output is accurate to within ₹50-100 of what your bank will quote. We round to the nearest rupee for display.

If you need exact matching to a specific bank's calculation, ask them for an amortization schedule. They have to provide it free of charge.