Start from your income, your other debts and the cash you have for a down payment. This works out the most a lender's usual debt-to-income rule allows, what that home costs you every month, and which limit is holding you back.
Housing costs are principal and interest, property tax, homeowners insurance, HOA dues, and private mortgage insurance whenever the down payment is under 20% of the price, estimated at 0.75% of the loan a year, the same estimate the mortgage calculator uses. The price is the largest one whose total monthly cost fits under both limits, found to the dollar. Closing costs are not included, so the cash you enter should be what is left for the down payment after them. Income is before tax, because that is what lenders measure. Nothing you type is saved or sent anywhere. The link button copies your numbers into the page address and nowhere else.
Lenders commonly cap total housing costs at about 28% of gross monthly income and all debt payments, housing included, at about 36%. The calculator finds the most expensive home whose payment, property tax, insurance, PMI and HOA dues fit under both limits.
A long-standing lending guideline: no more than 28% of gross income on housing costs and no more than 36% on all debt payments together. Some loan programs approve higher ratios, and you can change both limits on the page.
The calculator shows both for your numbers: what another $10,000 down adds to the price you can afford, and what half a point off the rate adds. Putting 20% down also removes mortgage insurance from the monthly cost. How mortgages work explains each piece of the payment.