Most borrowers think of a loan as a monthly payment. The Interest Bleed Calculator reframes it as a lifetime cost: the total dollars of interest you will hand the lender over the life of the loan if you make only the scheduled payments, versus how much you save by paying extra. Seeing the lifetime number, often two to three times the original loan amount, is what finally motivates most people to attack their debt seriously.
A standard amortizing loan front-loads interest. In the first year of a 30-year mortgage, roughly 80 percent of every payment goes to interest, not principal. The tool runs the full amortization schedule under your baseline and then re-runs it with your accelerated payment, comparing total interest paid and payoff date. The difference between those two interest totals is what you save by paying extra.
A 300,000 dollar mortgage at 7 percent for 30 years has a payment of 1,996 dollars and total interest paid over the life of the loan of 418,527 dollars. Add an extra 250 dollars a month and the loan pays off in 23 years, 4 months, with total interest of 282,931 dollars. That extra 250 dollars saves you 135,596 dollars of interest and shaves nearly seven years off the payoff date.
Why is the early interest cost so high?
Because interest is calculated on the outstanding balance. When the balance is large (early in the loan), most of the payment goes to interest. As the balance shrinks, more of the payment goes to principal.
Are biweekly payments worth it?
Biweekly payments add roughly one extra full payment per year, which trims a 30-year mortgage by about four to five years. The math is the same as making 1/12 extra principal payment each month.
Should I prepay my mortgage or invest the difference?
If your mortgage rate is below 5 percent, investing usually wins long-term. Above 6 percent, prepayment is a guaranteed risk-free return that is hard to beat. Between 5 and 6 percent is personal preference.
Does my loan have a prepayment penalty?
Most modern residential mortgages do not, but commercial loans and some older mortgages do. Check your loan documents before sending large lump sums.
Why does paying extra early save so much more than paying extra late?
Because you eliminate years of interest accrual on that prepaid principal. A 1,000 dollar prepayment in year two of a 30-year mortgage avoids 28 years of compounding interest. The same prepayment in year 25 avoids only five years.
This page is for general educational information only. It is not financial, tax, legal, or medical advice. Consult a qualified professional before making decisions based on this tool.