Flat vs Reducing Interest Calculator
A gold loan, a used-car plan or a dealer's consumer-durable offer may advertise 12% a year and still cost almost twice as much as a 12% housing loan. The difference is the method: flat interest is calculated on the original principal for the whole tenure, while reducing balance charges only on what you still owe. This page prices the same loan under both rules.
Enter values
Results
- Extra interest on a flat-rate quote
- ₹32,856.97
- Interest at flat rate
- ₹72,000.00
- Interest at reducing balance
- ₹39,143.03
- EMI at flat rate
- ₹7,555.56
- EMI at reducing balance
- ₹6,642.86
How is the Flat vs Reducing Interest calculated?
Enter the loan amount, the quoted annual rate and the tenure in years. Flat interest is principal × rate × years, divided across equal instalments; reducing balance runs the standard EMI formula and counts the interest you actually pay. The results give both totals, both instalments, and the gap between them — what the flat method adds to your bill.
Formula
Flat: interest = P × annual rate% × years, and EMI = (P + interest) ÷ months. Reducing: EMI = P × r × (1 + r)^n ÷ ((1 + r)^n − 1) with r the monthly rate and n the instalments, and interest = EMI × n − P. The flat method ignores the outstanding balance, which is why the same percentage costs far more.
Example
₹2,00,000 at 12% for 3 years, priced both ways. Flat: interest = 2,00,000 × 12% × 3 = ₹72,000, with an EMI of ₹7,555.56. Reducing: EMI ₹6,642.86 and interest ₹39,143.03. The flat quote costs ₹32,856.97 more, and because that gap is pure pricing, 12% flat equals about 21.2% on a reducing balance.
Things to remember
The agreement always states which method applies; sales desks rarely spell out what it costs. Before signing, ask whether the quote is flat or reducing, convert it here, and compare total interest rather than the headline percentage. On very short tenures the gap narrows; beyond two years it dominates.
Frequently Asked Questions
How do I convert a flat rate to a reducing rate?
There is no single multiplier, because the equivalent depends on the tenure. A three-year loan at 12% flat matches about 21.2% reducing, and a one-year loan about 21.5%. Enter the quote here and match the instalments to convert any flat offer precisely.
Which is better, a flat or a reducing interest rate?
Reducing balance is always cheaper when both quotes carry the same percentage, because you stop paying interest on money already returned. A flat offer can still compete if its percentage is much lower — compare total interest here rather than the advertised rate.
Where do lenders still use flat rates?
Gold loans, many used-car and consumer-durable finance plans, and some NBFC dealer tie-ups are priced flat. Housing, auto and personal loans from banks run on reducing balance. Ask for the method in writing before comparing two offers side by side.
Why is my gold loan EMI higher than I expected?
Because flat interest runs on the full sanctioned value for the entire tenure. ₹2,00,000 borrowed for three years at 12% flat adds ₹72,000 regardless of how promptly you repay, and the reducing equivalent of that quote sits above 21%.
Related Calculators
- EMI CalculatorLoan & EMICalculate your monthly EMI, total interest payable and total payment for any loan, with a worked example and repayment summary.
- Home Loan EMI CalculatorLoan & EMICalculate the EMI, total interest and first-year interest on a home loan of any amount and tenure.
- Car Loan EMI CalculatorLoan & EMIWork out the EMI, total interest and interest as a share of the on-road price for a car loan.
- Personal Loan EMI CalculatorLoan & EMIFind the EMI, total cost and interest-to-principal ratio on a personal loan before you sign.