Loan comparison
Flat vs reducing interest rate: compare the real loan cost
Understand why identical quoted rates can create different EMI amounts and total interest under flat and reducing-balance methods.
Updated August 26, 2026 · 5 min read
Flat interest keeps using the original principal
A flat-rate calculation applies the quoted rate to the original loan amount for the full tenure. Interest does not reduce in the calculation as instalments are paid, even though the borrower is gradually repaying the principal.
The total flat interest is added to the principal and divided across the repayment months. This makes the arithmetic simple, but the quoted rate cannot be compared directly with a reducing-balance rate.
Reducing interest follows the outstanding balance
A reducing-balance loan calculates each month's interest from the principal still outstanding. Part of every EMI repays interest and part reduces the balance used for the next calculation.
When the amount, tenure, and quoted rate are identical, the reducing method usually produces less total interest than the flat method. The calculator shows both results and estimates an equivalent reducing annual rate for context.
Compare the written total, fees, and repayment schedule
Do not choose a loan from the headline rate alone. Compare the monthly instalment, total interest, processing charges, taxes, insurance, advance instalments, and any compulsory products shown in the offer.
For regulated retail and MSME term loans in India, the Key Fact Statement is designed to present key terms and the annual percentage rate in a standard format. Use the lender's document as the final source of truth.
Put this guide into practice
Use the related calculators
Put the steps in this guide into practice with a focused calculator, then return here to check an assumption or compare another scenario.
Sources and further reading