Rate Impact Calculator

Last updated 2026-02-24

See what rate changes mean for you

The Rate Impact calculator in Plan > Calculators models how interest rate changes affect all your liabilities. Instead of guessing, you'll know exactly how much more (or less) you'd pay each month.

What it does

Enter a rate change (e.g. +0.25% or -0.50%) and the calculator shows the impact across every loan you have recorded in Finance Frank:

  • Current monthly payment — what you're paying now
  • New monthly payment — what you'd pay after the rate change
  • Monthly difference — the dollar change per month
  • Annual difference — the total extra (or saved) over a year

Loan types

The calculator handles both principal & interest (P&I) and interest-only mortgages correctly. Each loan type uses the appropriate repayment formula so the numbers are accurate.

How to use it

  1. Make sure your loans are recorded on the Wealth page with current balances and interest rates
  2. Navigate to Plan > Calculators
  3. Select the Rate Impact calculator
  4. Enter the rate change amount (positive for increases, negative for decreases)
  5. Review the per-loan and total impact

Tips

  • Use this before RBA rate announcements to prepare for different scenarios
  • Model a range of changes (e.g. +0.25%, +0.50%, +1.00%) to stress-test your budget
  • If the impact is significant, consider fixing part of your loan — see Refinance Comparison Calculator
  • Keep your loan balances up to date for the most accurate projections

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