Mortgage calculator

California Mortgage Payment Calculator

Work out the full monthly cost of a California home — principal and interest, property tax, homeowners insurance, HOA dues, and mortgage insurance — from numbers you enter.

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Assumptions this tool makes

The interest rate is a hypothetical example rate you enter; it is not an offer, and no lender has quoted it.
Property tax is charged on the full price at the tax rate you enter. Under Proposition 13 a purchase sets the base year value, and the factored value rises at most 2% a year, so a long-held home is often taxed on far less than its market value.
Mortgage insurance is charged only when the loan is more than 80% of the price. At exactly 20% down the mortgage insurance line is $0.
Insurance and HOA dues are the amounts you enter, held flat for every month. Real premiums and dues change over time.
The loan is a fixed-rate, fully amortizing loan paid monthly. Adjustable rates, interest-only periods, and extra principal payments are not modeled.
Nothing here is a quote, an approval, or a promise of any rate or payment.

The formula

Loan amount = price − down payment. Monthly principal and interest = loan × r × (1 + r)^n ÷ ((1 + r)^n − 1), where r = annual rate ÷ 100 ÷ 12 and n = years × 12; at a 0% rate the payment is simply loan ÷ n. Monthly tax = price × tax rate ÷ 100 ÷ 12. Monthly insurance = annual insurance ÷ 12. Monthly mortgage insurance = loan × PMI rate ÷ 100 ÷ 12, charged only when loan > 80% of price. Total = principal and interest + tax + insurance + HOA + mortgage insurance.

A worked example

Price $950,000, down payment $190,000, hypothetical example rate 6.5%, 30-year term, tax rate 1.16%, insurance $2,400 a year, HOA $0, PMI rate 0.5%.

Loan amount: $950,000 − $190,000 = $760,000.
Principal and interest: r = 0.065 ÷ 12 = 0.0054167, n = 360; $760,000 × r × (1 + r)^360 ÷ ((1 + r)^360 − 1) = $4,803.72.
Property tax: $950,000 × 1.16% ÷ 12 = $918.33 a month.
Insurance: $2,400 ÷ 12 = $200.00 a month.
Mortgage insurance: the down payment is exactly 20% of the price, so the loan is exactly 80% of the price and mortgage insurance is $0.
Total: $4,803.72 + $918.33 + $200.00 + $0 + $0 = $5,922.05 a month.

How to read your result

If mortgage insurance is not $0, you are borrowing more than 80% of the price. Raising the down payment to exactly 20% removes that whole line at these inputs.
Change the rate by a quarter point and rerun before you react to a total: on a $760,000 loan the payment moves by roughly $125 a month for each 0.25% of rate.
If the tax line looks low for a home you have owned for years, that is Proposition 13 at work — a buyer at today's price restarts the base year value at the purchase price.
Compare totals across homes, not principal and interest alone: two homes at the same price can differ by hundreds a month in tax, insurance, and HOA dues.