Get your monthly payment, total interest, and the impact of extra payments — plus a refinance break-even check to see if a refi is worth it.
P·r(1+r)ⁿ / ((1+r)ⁿ−1)
Standard amortized P&I payment.
(Payment × n) − Principal
Lifetime cost of borrowing.
Amortize with extra principal
Months to zero with extra payments.
Baseline interest − extra-pay interest
What the extra payments save you.
Old payment − New payment
Monthly reduction from refinancing.
Refi cost / Monthly savings
Months to recoup the closing cost.