Free mortgage payoff calculator to evaluate options to pay off a mortgage earlier, such as extra payments, bi-weekly payments, or paying back altogether. Use SmartAsset's free Texas mortgage loan calculator to determine your monthly payments, including PMI, homeowners insurance, taxes, interest and more.Use the extra payment calculator below to help determine how advantageous it is to pay a little extra each month toward your mortgage. Use this free Texas mortgage calculator to estimate your monthly mortgage payments and annual amortization.