How the payments are compared
Both payments are calculated on the same balance and remaining amortization, using the rates you entered.
Why the gap alone does not decide
Add transfer costs, prepayment privileges, portability, and the penalty if you sell before maturity.
What the calculation ignores
This confirms no quoted rate. A transfer means a fresh review of your file at the lender taking you on.
A worked example
$300,000 balance, 20 years of amortization left. At 5.5%, the monthly payment is $2,053.17. At 4.5%, it is $1,891.22, which is $161.96 less a month, about $9,700 less in payments over a 5-year term. If switching lenders costs $1,500 in fees, the net saving is still about $8,200: that difference, not only the rate, is what to compare.
Common questions
Can I renew with a different lender? Yes, at maturity, without a penalty. The new lender may require a new appraisal or transfer fees; the tool lets you enter them as switching costs to see the net effect. Why not just sign my lender’s offer? You can, but the offer carries over its own conditions, not necessarily the best available. Comparing before the deadline gives you a basis to negotiate, even if you stay.
Next step
Send me the offer you received, your balance, and the maturity date: I’ll compare it with what other lenders offer on the same basis.