Read the result in layers
The large monthly figure adds the scheduled principal-and-interest payment to the tax, insurance, HOA, and PMI amounts you entered. The Consumer Financial Protection Bureau distinguishes principal and interest from the total monthly payment because the latter commonly includes taxes, homeowners insurance, and mortgage insurance; HOA charges may be separate. See the CFPB explanation of total monthly payment.
| Result | Use | Do not assume |
|---|---|---|
| Principal & interest | Compare loan structures when principal, rate, and term are held constant. | That it is the complete monthly cost. |
| All-in estimate | Place the entered ownership charges beside the loan payment. | That tax, insurance, HOA, or PMI will stay unchanged. |
| Planned outflow | See the cash effect of an optional extra-principal payment. | That a servicer will automatically apply every extra dollar to principal. |
| Annual schedule | Trace principal, interest, and balance using unrounded internal values. | That it replaces a lender or servicer statement. |
Calculation order
- The down payment is subtracted from the home price to produce the loan principal.
- The fixed-rate payment is calculated from principal, monthly rate, and number of monthly payments.
- Annual property tax and insurance are divided by 12; monthly HOA and PMI are then added.
- The optional extra amount is applied to principal after that month's interest. The final payment is reduced when the remaining balance is smaller than the planned payment.
- Scenario rows change one rate or term assumption while leaving the property price and entered ownership costs untouched.
M = P × [r(1 + r)n] / [(1 + r)n - 1]
P is the loan principal, r is the annual interest rate expressed as a decimal and divided by 12, and n is the loan term in months. At a 0% rate, the payment is simply P divided by n.
The schedule uses full-precision values internally and rounds only what is displayed. The CFPB's explanation of mortgage amortization confirms the basic payment behavior: early payments direct more money to interest, while the principal share rises as the balance falls. Read how paying down a mortgage works.
Public verification record
This version is checked against deterministic cases that anyone can reproduce. The automated test file is part of the site build, and the broader test vectors are documented on the methodology page.
| Principal | Rate / term | Expected P&I | Reason for test |
|---|---|---|---|
| $300,000 | 6.00% / 30 years | $1,798.65 | Standard fixed-rate amortization case. |
| $1,200 | 0.00% / 12 months | $100.00 | Confirms the explicit zero-rate branch. |
| $336,000 | 6.40% / 30 years | $2,101.70 | Matches the page's default loan inputs before ownership costs. |
Replace estimates in the right order
Begin with approximate local costs if you are still exploring. As the purchase becomes real, replace them with documents: property-tax information from the local authority, an insurance quote, HOA disclosures, and the lender's PMI and Loan Estimate. The CFPB's interactive Loan Estimate explainer identifies where to check the loan amount, projected payment, mortgage insurance, taxes, insurance, assessments, closing costs, and cash to close.
When comparing lenders, keep tax and insurance assumptions consistent. A lender does not control those costs, so a lower estimate does not by itself make that loan cheaper. Compare principal and interest, lender-controlled upfront costs, and credits separately, then rebuild the same all-in budget for each offer.
Boundaries of the model
Property tax, homeowners insurance, HOA, and PMI are user-supplied dollar amounts. The tool does not infer them from ZIP code, loan program, credit profile, or down-payment percentage.
The model does not include maintenance, utilities, flood or other supplementary insurance, tax deductions, closing costs, adjustable rates, points, temporary buydowns, refinancing, late fees, changing escrow bills, or rules for canceling mortgage insurance. Extra payments are treated as principal immediately; verify how the servicer requires them to be labeled and whether the loan documents contain a prepayment penalty.
U.S. scope: Inputs and results use USD, and the cited documents reflect U.S. mortgage practice. Elsewhere, adapt the tax, insurance, lending-term, and fee assumptions to local rules.
This page is educational and scenario-based. Real loan offers depend on lender rules, credit profile, taxes, insurance, property details, and timing.