Last Updated: August 13, 2026
Learn the critical differences between reducing balance and flat interest rates. See how banks calculate your monthly EMI and amortization schedules.
When applying for a car loan, home mortgage, or personal credit, you will encounter two main methods banks use to calculate interest: Flat Interest Rate and Reducing Balance Rate. Understanding these methods can save you thousands in interest charges.
Under a flat interest rate, the interest is calculated on the full initial principal amount throughout the entire tenure of the loan. This means your interest charges do not decrease even as you repay the loan principal monthly.
With a reducing balance rate, the interest is calculated monthly only on the outstanding principal balance. As you pay your monthly EMI, a portion goes toward reducing the principal, meaning the next month's interest is calculated on a smaller amount.
A flat rate of 10% may sound cheaper than a reducing rate of 14%, but in reality, the reducing balance method often ends up being cheaper because the interest component decreases over time. You can run amortization scenarios using our Loan Calculator to verify this before signing bank contracts.
Flat rates are calculated on the full principal, so the percentage number is lower, making it look attractive. However, since the principal reduces in reality, the effective reducing rate is always higher than the flat rate number.
Reducing balance loans are much better for prepayments. Any extra payment directly reduces the principal, immediately lowering your interest charges for all subsequent months.