The EMI formula
The standard EMI formula is:
EMI = P · r · (1+r)^n / ((1+r)^n − 1)
- P — principal (loan amount)
- r — monthly interest rate as a decimal (annual rate ÷ 12 ÷ 100). A 9% annual rate gives r = 0.0075.
- n — tenure in months. A 20-year loan has n = 240.
This is reducing-balance EMI — interest each month is computed on the outstanding principal, which falls every month. The same formula is used by every Indian bank (SBI, HDFC, ICICI, Axis, etc.), every US mortgage lender, and every UK/EU consumer-loan provider for fixed-rate loans.