PITI: the four components of a mortgage payment
A mortgage payment consists of four parts: Principal (repaying the loan amount), Interest (cost of borrowing), Taxes (property tax, typically 1-2% of home value annually), and Insurance (homeowner's insurance and PMI if down payment <20%). Our calculator breaks down each component and shows how they combine into your total monthly payment. Many online calculators show only P&I, but PITI is the true cost of homeownership and what lenders use for debt-to-income ratio qualification.
PMI (Private Mortgage Insurance) is required when the down payment is less than 20% of the home value. PMI rates range from 0.5% to 1.5% of the loan amount annually. Our calculator factors in PMI and shows when it drops off (automatically at 78% loan-to-value, or at 80% if you request cancellation). Factoring PMI into your budget can mean the difference between qualifying for a loan and being denied.
Comparing mortgage scenarios
The calculator lets you compare up to three scenarios side by side: different down payment amounts, interest rates, or loan terms (e.g., 30-year fixed vs 15-year fixed vs 5/1 ARM). The 15-year mortgage has higher monthly payments but saves significantly in total interest because less interest accrues over the shorter term. However, the 30-year offers flexibility — you can always make extra principal payments to accelerate the payoff while preserving the lower minimum payment as a safety net.
Our calculator also models the impact of discount points (prepaid interest that reduces the rate). One point costs 1% of the loan amount and typically reduces the rate by 0.25%. The break-even period is the time required for the monthly savings to exceed the points paid. If you plan to stay in the home past the break-even point, buying points makes financial sense.
How to use the Mortgage Calculator
Step 1: Enter the home price or total loan amount. If you are making a down payment, enter the home price separately and the down payment amount or percentage.
Step 2: Enter the down payment. A 20% down payment avoids Private Mortgage Insurance (PMI). Lower down payments are possible but add PMI to your monthly cost.
Step 3: Enter the interest rate (APR). Check current rates from multiple lenders — even a 0.25% difference significantly impacts total interest over 30 years.
Step 4: Select the loan term — 30-year fixed is most common, 15-year fixed saves substantial interest, and adjustable-rate (ARM) options start lower but carry risk.
Step 5: Enter property tax rate, homeowner insurance, and HOA fees if applicable. These are part of your true monthly housing cost (PITI).
Step 6: Review the monthly payment breakdown showing principal, interest, taxes, insurance, and PMI. Compare different scenarios using the side-by-side comparison feature.
Step 7: Examine the amortization schedule to see how much of each payment goes to interest vs principal over the life of the loan.
Common mistakes and how to fix them
Error: Ignoring PMI costs. If your down payment is less than 20%, PMI adds 0.5-1.5% of the loan amount annually to your payment. PMI drops off automatically at 78% loan-to-value, but factor it into your budget.
Error: Only looking at principal and interest. The true monthly cost includes taxes, insurance, and HOA fees. A $1500 P&I payment can become $2200+ with all components included.
Error: Not comparing total interest paid. A 30-year mortgage at 6% on a $300,000 loan costs approximately $347,000 in interest — more than the principal itself. Compare this to a 15-year term.
Error: Forgetting about closing costs. Closing costs are typically 2-5% of the loan amount. On a $300,000 loan, that is $6,000-$15,000 in upfront costs that affect your break-even calculation.
Error: Assuming the lowest rate is always best. Discount points (prepaid interest) reduce the rate but cost money upfront. Calculate the break-even period to see if buying points makes financial sense for your situation.
Tips and best practices
Use the amortization table to find your break-even point for refinancing. If the monthly savings from a lower rate exceed closing costs within the time you plan to stay in the home, refinancing is worthwhile.
Include HOA fees in your monthly budget even though they are not part of the mortgage payment. HOA fees can range from $100 to $500+ per month and affect your total housing cost.
Compare at least three scenarios: 30-year fixed, 15-year fixed, and a 5/1 ARM. This gives you a complete picture of payment options and total costs for different loan structures.
For first-time buyers, explore FHA loans (3.5% down) and conventional loans with 3% down. Compare the total cost including PMI against saving for a 20% down payment.
Factor in property tax increases over time. Property taxes typically increase 2-3% annually, which increases your monthly payment even with a fixed-rate mortgage.