Mortgage & Affordability Calculator

How to use this calculator

Read the full guide: First-time buyer checklist

How it works

Enter home price, down payment, interest rate, and loan term. The calculator derives your loan amount, monthly principal and interest, and optional lines for property tax, homeowners insurance, HOA, and PMI. It can estimate how much home fits your income using a target payment ratio, and it builds an amortization schedule showing how each payment splits between principal and interest over time.

Worked example

Example: $400,000 home, 10% down ($40,000), 6.75% rate, 30-year term. Loan amount $360,000. Monthly P&I is about $2,335. Add $450 taxes, $125 insurance, and $160 PMI and total housing is near $3,070/month before HOA. Over 30 years you pay roughly $840,000 in scheduled P&I, of which about $480,000 is interest in this illustration.

Why principal and interest is the smaller half of the story

In the example above, the loan payment is $2,335 but the actual bill is closer to $3,070. That $735 gap is taxes, insurance, and mortgage insurance, and it is the single most common reason a buyer's budget breaks after closing. Depending on where you buy, those lines add 25 to 40 percent on top of principal and interest, and in high-tax counties in New Jersey, Illinois, or Texas the gap can be larger still.

Property tax is the biggest variable and the one worth looking up rather than estimating. Two houses at the same price in neighboring towns can differ by $400 a month in tax. Pull the actual figure from the county assessor for the specific address, and remember that a recent sale often triggers a reassessment, so the current owner's bill may be lower than yours will be.

Homeowners insurance has also stopped being a rounding error. Premiums have risen sharply in coastal and wildfire-exposed states, and a quote on the specific property beats any statewide average. If the house sits in a FEMA flood zone, flood insurance is separate, required by your lender, and not cheap.

How the rate and the term change what you actually pay

On a $360,000 loan, each quarter point of rate is roughly $60 a month. Going from 6.75 percent to 6.25 percent saves about $115 monthly and around $41,000 over a full 30-year term. That is why shopping three lenders is worth a few hours: the spread between the best and worst quote a single borrower receives on the same day is routinely a quarter point or more.

Term is a bigger lever than most buyers expect. The same $360,000 at 6.75 percent costs about $2,335 a month over 30 years and about $3,186 over 15. The 15-year payment is 36 percent higher, but total interest falls from roughly $480,000 to about $213,000. Shorter terms also usually price a bit below 30-year rates.

The practical middle path, if the 15-year payment is out of reach, is to take the 30-year loan and send extra principal voluntarily. You get most of the interest savings while keeping the lower required payment as a cushion if your income changes. The loan repayment calculator shows exactly what a given extra amount buys you.

Down payment, PMI, and when 20 percent is worth waiting for

Putting less than 20 percent down on a conventional loan means private mortgage insurance, typically 0.3 to 1.5 percent of the loan annually depending on credit score and loan-to-value. On the example loan that is the $160 monthly line. PMI buys you nothing except the ability to borrow sooner, which is sometimes exactly what you need.

The important detail is that conventional PMI is not permanent. You can request removal once your balance reaches 80 percent of the original value, and it must be dropped automatically at 78 percent. FHA mortgage insurance works differently and generally lasts the life of the loan if you put less than 10 percent down, which is a real cost worth comparing before choosing a program.

Whether to wait and save a larger down payment depends on what prices and rates do while you save, and nobody knows that. What you can control is the math: run the payment at your current savings level and again at 20 percent, and see whether the PMI and higher balance actually change your decision or just your preference.

Using the affordability estimate honestly

The income-based affordability feature applies a target ratio, commonly 28 percent of gross income for housing. It answers what a lender will likely allow, which is a different question from what you should spend. Approval math does not know about childcare, tuition, a car you will need to replace, or the fact that you would like to keep saving.

A useful discipline is to pick your own payment ceiling first, then work backward to a price. If you can comfortably carry $2,600 a month all-in, model that rather than the $2,900 a lender would approve, and treat the difference as your margin for repairs and rate surprises.

Once you have a payment target, check it against your full debt picture with the DTI calculator, then pressure-test it in the budget planner to see what it leaves for everything else.

What this calculator does not include

• Does not produce a Loan Estimate, APR under Regulation Z, or lender-specific fees.
• Tax and insurance are estimates you enter; they are not pulled from county records.
• PMI is simplified; actual premiums vary by credit, LTV, and insurer.
• Does not model ARMs, interest-only periods, or buydowns.
• Affordability from income uses rules of thumb, not automated underwriting.

Frequently asked questions

Does this include closing costs?

You can enter closing costs for cash-to-close context, but ongoing PITI is separate. See the closing costs Learn guide for fee categories.

Why is my lender payment different?

Lenders may round differently, use exact tax bills, and include escrow cushions. Your Loan Estimate is the binding planning document.

What payment ratio should I use for affordability?

Many planners use 28% to 36% of gross income for housing, but your comfortable number may be lower. Pair with the DTI calculator for debt-inclusive view.

Can I model extra principal payments?

Yes, where the tool exposes extra payment fields. Extra payments reduce interest but are not guaranteed to match servicer posting rules.

Is the amortization schedule official?

It is a mathematical schedule for education. Your servicer statement is authoritative.

Educational tool only. Not a Loan Estimate, appraisal, tax advice, or legal opinion. Numbers are illustrative unless you enter your own verified inputs.