Mortgage rate-change calculator
Compare remaining payments and interest before and after a rate change
Enter completed monthly payments; the new rate applies only to the remaining term.
Assumes the rate changes on a payment boundary; the contract controls actual reset timing.
Calculation result
Example
Input
CNY 1,000,000 · 30 years · 60 paid · 4.2% to 3.5%
Example result
Old and new payment plus remaining-interest difference
A negative interest change means an estimated reduction.
Technical details & limits
The balance at reset comes from the original amortization. The new rate applies only to remaining payments.
About this tool
Compare payment and remaining interest before and after a mortgage rate reset.
Use cases
- See how the payment and total interest move after a rate reset.
- Check the remaining schedule when the rate changes partway through.
- Compare the total cost with and without the change.
How to use
- Enter the original principal, term, instalments paid and the original rate.
- Enter the new rate.
- The result compares payment, total interest and total repaid before and after.
Notes
Both rates are yours to enter; the page supplies no current LPR or spread. The real reset date and when it takes effect are set by the contract and may differ from the period used here.
FAQ
- Does a mortgage rate adjustment recalculate interest already paid?
- This tool applies the new rate only to the outstanding principal and remaining periods at the adjustment point, without changing past interest. For an original 360-period loan with 120 periods completed, the new scenario covers the remaining 240. It assumes that the new rate stays fixed for that modeled remainder. Later repricing, fees, or exceptional account transactions require separate consideration when comparing the scenario with an actual lender statement.
- How do I compare mortgage payments when a rate falls from four to three percent?
- Enter the original loan and completed periods first, then compare the remaining repayment using 4% and 3% as the two rate scenarios. Those percentages are illustrative inputs, not current offers. The adjusted payment depends on outstanding principal, remaining term, and repayment method. Simply multiplying the old payment by the ratio of the rates would ignore principal repayment and the structure of the amortization calculation.
- Can the mortgage rate adjustment calculator predict future LPR changes?
- This calculator cannot predict future LPR values; it models the entered replacement rate as fixed for the remaining term. Entering 3% with 120 periods remaining assumes that rate applies throughout those 120 periods. If the contract reprices again later, repeat the calculation with the updated conditions. The result is a conditional repayment scenario rather than a forecast of interest rates or a promise about future lender charges.
Related tools
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