Interest Calculator (Flat vs Reducing)
Calculate and compare flat-rate and reducing-balance interest side by side, with monthly or yearly instalment frequency, a total-interest comparison chart and a year-wise breakdown.
Flat rate
Reducing balance (lower interest)
Total interest comparison
Outstanding balance over time
What is Interest Calculator (Flat vs Reducing)?
When borrowing or lending in India, interest quotes can be misleading. A flat interest rate calculates interest on the entire original principal for the entire loan tenure, ignoring that you are steadily paying down the principal with each instalment. In contrast, a reducing balance rate (diminishing balance) recalculates interest periodically based only on the outstanding loan balance. This calculator lets you input the principal, nominal annual rate, tenure in years, and payment frequency (monthly or yearly) to evaluate both methods side by side. It provides the exact periodic instalment, total interest paid, aggregate repayment amount, net financial difference between the two methods, and an annual amortization breakdown.
How to use Interest Calculator (Flat vs Reducing)
- 1Enter the total principal loan or deposit amount in rupees (₹).
- 2Enter the quoted annual interest percentage rate.
- 3Specify the tenure duration in years.
- 4Select your repayment frequency: Monthly (standard EMI) or Yearly instalments.
- 5Compare the flat vs reducing total interest, periodic payment, and amortization schedule.
Key features
Flat vs Reducing Side-by-Side
Direct comparison of flat-rate interest and reducing-balance (diminishing) interest models.
Monthly & Yearly Repayments
Supports both monthly EMI schedules and annual bullet/installment payment structures.
Payment Schedule Amortization
Exact breakdown of principal and interest components paid per period throughout tenure.
Visual Total Interest Chart
Comparative visual bar chart highlighting the dramatic interest disparity between the two models.
Year-by-Year Table
Detailed annual amortization breakdown tracking opening balance, interest, principal, and closing balance.
Instant Cost Delta
Calculates the exact rupee savings when choosing reducing balance over flat rate.
Examples & use cases
Personal Loan Flat vs Reducing (₹1,00,000 at 10% for 3 Years Monthly)
At 10% flat rate over 3 years, total interest is ₹30,000 (₹3,611/mo). Under reducing balance, total interest is ₹16,162 (₹3,227/mo), saving ₹13,838.
Two-Wheeler Loan (₹50,00,000 / ₹50,000 at 12% for 2 Years Monthly)
On ₹50,000 at 12% for 2 years, flat interest yields ₹12,000 in interest (₹2,583/mo). Reducing balance yields ₹6,620 (₹2,359/mo), demonstrating that flat rates cost almost double in interest.
Business Loan (₹5,00,000 at 14% for 5 Years Yearly)
Flat rate costs ₹3,50,000 in interest over 5 yearly installments of ₹1,70,000. Reducing balance costs ₹2,28,349 over 5 equal installments of ₹1,45,670.
Frequently asked questions
Helpful guides & tutorials
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