The short version
- Flat interest uses the original principal throughout the tenure.
- Reducing-balance interest is charged on the outstanding balance.
- The same nominal rate does not mean the same total cost.
- Compare total interest, fees, insurance and cash outflow—not EMI alone.
How flat interest works
Under a basic flat-rate illustration, interest is calculated on the original principal for the full tenure. Total interest equals principal × annual rate × years, and the combined principal plus interest is divided across installments.
Because the interest base does not fall as principal is repaid, a flat rate usually represents a higher effective cost than the same numerical reducing-balance rate. A small EMI can also result from a longer tenure rather than a cheaper loan.
How reducing balance works
In a reducing-balance loan, each installment contains interest on the outstanding principal and a principal repayment. Early installments contain more interest; later installments contain more principal. The standard EMI formula assumes a fixed periodic rate and equal scheduled installments.
Banks can differ because of day-count conventions, floating-rate resets, rounding, repayment dates and capitalization rules. A public calculator is a comparison tool, not the bank’s binding repayment schedule.
What to compare in an offer
Compare the calculation method, annual rate, effective rate where disclosed, tenure, processing fee, insurance, valuation charges, prepayment conditions and total cash outflow. Ask for an amortization schedule before signing.
If one lender quotes a flat rate and another quotes a reducing rate, do not compare the percentages directly. Model both on the same principal, start date and tenure.
Why dates and rate changes matter
A month-end loan start can produce repayment dates that lenders handle differently. A floating-rate loan may be re-amortized after a rate reset, changing EMI, tenure or both.
Use scenarios rather than one optimistic number: current rate, a higher-rate case and a prepayment case. This shows whether the repayment remains affordable if conditions change.
Where to check the details
For an important payroll, filing or financial decision, open the source itself and check whether anything has changed since this guide was updated.
- Nepal Rastra Bank — Banks and Financial Institutions Regulation Department
Official regulatory information and directives; confirm lender-specific disclosures.