可嵌入的混合利率房贷计算器，回答“保留还是合并”的问题

计算器中的定义

Blended interest rate

A single rate that represents the cost of two loans together, calculated as the balance-weighted average of their rates. A $250,000 loan at 5.5% and a $50,000 loan at 8.5% blend to 6.0%. It is a comparison figure, useful for weighing two loans against one refinance at a single rate; no lender actually charges it.

Balance-weighted average

An average in which each loan’s rate counts in proportion to its balance: multiply each rate by its balance, add the results, and divide by the total balance. A large first mortgage dominates the blend, so even a high-rate second mortgage moves the blended rate only modestly if its balance is small.

First mortgage

The primary loan secured by the home, which holds first lien position: in a foreclosure or sale it is repaid before any other mortgage. Because of that priority it usually carries the lower rate. In this calculator, its balance and rate are the larger weight in the blended rate.

Second mortgage

A loan secured by the same home that ranks behind the first mortgage, such as a home equity loan or HELOC. Because the lender is repaid second, the rate is usually higher. This calculator estimates its payment separately and combines it with the first mortgage to show total monthly cost.

HELOC

A home equity line of credit: a revolving credit line secured by the home, usually in second lien position. Rates are commonly variable, and payments may be interest-only during the draw period. This calculator amortizes the second balance at a fixed rate, so an actual HELOC payment may differ from the estimate.

Combined monthly payment

The sum of the estimated principal-and-interest payments on both loans, each amortized over the term you enter. It excludes taxes and insurance. Comparing it with the payment on a single refinanced loan at a quoted rate shows whether consolidating would lower the monthly cost, separate from closing costs.

Total balance

The first mortgage balance plus the second mortgage balance: everything currently owed against the home. It is the amount a single refinance would need to cover to replace both loans, before closing costs, and it is the base against which each rate is weighted in the blended rate.

Cash-out refinance

Replacing an existing mortgage with a larger new one and taking the difference in cash, or using it to pay off a second mortgage. The blended rate is the usual yardstick: if a new single loan’s rate is below the blend, consolidating may cut interest cost, though closing costs and a reset term also matter.