What PITI actually adds to the payment
PITI is principal, interest, taxes and insurance. Most calculators quote only the first two, which is why the number a lender gives you is higher than the one you worked out. On a $400,000 home with 10% down at 6.66% over 30 years, the Freddie Mac 30-year average on 30 July 2026, using national-average tax and insurance figures:
| Component | Monthly | Share |
|---|---|---|
| Principal and interest | $2,313 | 75% |
| Property tax (1.10% of value) | $367 | 12% |
| Homeowners insurance | $200 | 7% |
| PMI (below 20% down) | $186 | 6% |
| Total | $3,066 | 100% |
The three components after principal and interest come to $753 a month, which is 33% on top of the figure a P&I calculator shows. Property tax and insurance both vary widely by state and county, so treat those two rows as a starting point rather than a quote; the shape of the breakdown holds regardless. For the PMI row specifically, our PMI calculator gives the rate by loan-to-value band, how long you pay it, and the two dates on which it can be removed.
Why quoting P&I misleads you about affordability
This is the part that costs people a house. Lenders apply the 28% front-end rule to PITI, not to principal and interest, and the difference is larger than the 33% above suggests.
On a $9,000 monthly income, 28% allows $2,520 for the whole housing payment. Budget with a P&I calculator and you conclude you can support $2,520 of principal and interest, which is a loan of roughly $392,000. Work with PITI and the tax, insurance and PMI come out of that $2,520 first, leaving about $1,767 for principal and interest, which is a loan of roughly $275,000.
That is a difference of about $117,000 in what a lender will actually advance, from the same income, at the same rate, on the same day. It is why an approval figure so often arrives lower than expected, and why the order of the calculation matters more than the inputs.
How this calculator works
Unlike some markets, a US monthly housing payment is conventionally PITI: Principal, Interest, Taxes, and Insurance, plus PMI (Private Mortgage Insurance) if applicable and HOAdues if your property has them. The principal & interest portion uses the standard amortizing-loan formula:
M = P × r × (1+r)n ÷ ((1+r)n − 1)
where P is your loan amount (home price minus down payment), r is your monthly interest rate (annual rate ÷ 12), and n is your total number of monthly payments (term in years × 12). Property tax and insurance are typically collected monthly into an escrow account and paid on your behalf annually, which is why lenders quote them as part of your "monthly payment" even though they aren't part of the loan itself.
Worked example
Take a $400,000 home with a 10% down payment ($40,000), a 6.5% 30-year fixed rate, average property tax for your state, and typical homeowners insurance. Your loan amount is $360,000, giving a 90% loan-to-value, above the 80% threshold, so PMI applies automatically. Try adjusting the down payment to 20% ($80,000) in the calculator and watch the PMI line disappear entirely, since your LTV drops to exactly 80%.
What affects your monthly payment
- Down payment, crossing the 20% threshold removes PMI entirely and lowers your loan amount, both cutting your payment.
- Interest rate, the biggest driver of your principal & interest payment over a 30-year term.
- Location, property tax rates vary enormously by state and county; two identical homes can have very different PITI payments purely based on location.
- Loan term, 15-year loans have higher payments but dramatically lower total interest than 30-year loans.
A note on accuracy
This calculator computes on full, unrounded figures and only rounds to the cent for display, so the amortization schedule doesn't drift. PMI removal timing is estimated from your amortization schedule reaching 78% of your ORIGINAL home value, per the Homeowners Protection Act of 1998. For official consumer guidance, see the Consumer Financial Protection Bureau.