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LOANS / RATE METHOD

Flat vs Reducing Balance Calculator

Compare a flat-interest quote with reducing-balance amortization using the same principal, headline annual rate, and repayment term.

  • 01 Calculated in this tab
  • 02 Values stay in this browser tab
  • 03 Use boundary

Conversion input

Known value

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Calculation path

Flat interest stays tied to original principal for every year. Reducing-balance interest is embedded in an amortized payment and falls as principal is repaid.

Calculation path

Flat interest = original principal x rate x years; reducing payment uses monthly amortization.

What you provide

What you provide

  • Loan principal: Original amount financed under both methods.
  • Headline annual rate: Same numeric rate used to expose the method difference.
  • Repayment term: Whole years used by both comparisons.

What you receive

What you receive

  • Monthly payment under each method
  • Total interest under each method
  • Estimated extra cost of the flat method

Use boundary

Choose the maximum decimal places shown. This does not increase source accuracy.

A flat rate and reducing rate with the same percentage are not economically equivalent; use the method stated in the contract.

This is an educational planning estimate. Confirm lender, issuer, tax, accounting, and contractual rules with the relevant provider or qualified adviser before acting.