Estimated House Payment With Down Payment Calculator

This calculator estimates the monthly principal-and-interest payment on a home loan after accounting for a down payment. Enter the home price, down payment, annual interest rate, and loan term to see the estimated payment and total interest; taxes, insurance, and other housing costs are not included.

Formula

The estimated monthly payment is the fixed-payment loan formula applied to the amount borrowed after the down payment:

M = L × r / [1 − (1 + r)⁻ⁿ]

• M is the monthly principal-and-interest payment, in dollars.
• L is the loan principal, in dollars: home price minus down payment.
• r is the monthly interest rate as a decimal: annual APR divided by 1,200.
• n is the number of monthly payments: loan term in years multiplied by 12.

The total-interest estimate is monthly payment multiplied by the number of payments, minus the original principal: I = M × n − L. The payment is rounded to cents by the calculator, and the total uses that displayed rounded payment. The formula assumes the same rate and scheduled payment throughout the term.

Worked Example

Using the calculator’s default values—home price $350,000, down payment $70,000, APR 6.5%, and a 30-year term—the estimated loan principal is:

L = $350,000 − $70,000 = $280,000

Convert the annual rate to a monthly decimal and the term to months:

• r = 6.5 ÷ 1,200 = 0.0054166667
• n = 30 × 12 = 360 payments

Substitute those values into the fixed-payment formula:

M = $280,000 × 0.0054166667 ÷ [1 − (1 + 0.0054166667)⁻³⁶⁰] = $1,770.04 per month

Using the displayed payment, total scheduled payments are $1,770.04 × 360 = $637,214.40. Subtracting the $280,000 principal gives $357,214.40 in estimated total interest. These amounts exclude costs outside the loan-payment formula.

Assumptions

• The rate is fixed for the full term and is entered as an annual percentage rate.
• Payments are equal monthly payments, made at the end of each monthly period.
• Interest is calculated monthly using APR divided by 12; the calculator does not model daily accrual or rate changes.
• The figures exclude fees, closing costs, property taxes, homeowners insurance, mortgage insurance (PMI), escrow, utilities, and maintenance.

What the Down Payment Changes

A down payment reduces the amount financed. With the other inputs unchanged, borrowing less lowers the payment and the total interest calculated over the term. It does not directly change the interest rate, term, or costs that are paid separately.

For instance, a $70,000 down payment on a $350,000 home leaves a $280,000 loan. A $50,000 down payment on that same price would leave $300,000 to borrow. The calculator can estimate each payment by changing the down-payment input; it does not determine whether a particular down payment meets a lender’s requirements or changes any charges.

Down payment is not always identical to the amount of cash needed at closing. Other transaction expenses or prepaid items may be due, and they are not calculated here. For an estimate of the complete cash requirement, obtain those separate figures from the relevant provider and include them in your own budgeting.

How to Use and Interpret the Estimate

1. Enter the home price in dollars and the down payment in dollars. The down payment must be less than the home price so that the formula has a positive loan amount.
2. Enter the annual APR and the planned term in years. For a real transaction, use the rate and term supplied for your specific loan rather than treating the example defaults as a quote.
3. Read the first result as the scheduled monthly principal-and-interest payment. The second result estimates total interest across all scheduled payments.

Compare estimates only when the inputs and what is included are consistent. A longer term generally spreads repayment over more months, which can lower the scheduled payment while increasing the sum of interest paid, if the rate and principal are otherwise unchanged. The calculator does not account for extra payments, skipped or late payments, refinancing, or payoff before the scheduled end date.

Costs Beyond Principal and Interest

A monthly housing budget can include expenses that are absent from this result. Property taxes and homeowners insurance may be collected with a mortgage payment or paid separately, depending on the arrangement. Mortgage insurance, where applicable, is also not included. Closing expenses and ongoing costs such as repairs and utilities are separate from the loan’s principal-and-interest calculation.

To build a broader estimate, identify each expense separately and use figures relevant to the home and loan. Do not add a generic percentage to this calculator’s result and interpret it as a precise total: these costs vary, and the calculation has no inputs for them. Ask the lender for an itemized payment estimate and check which amounts may change over time.

Common Calculation Limits

• APR versus monthly rate: APR is entered as a percentage per year; the formula converts it to a monthly decimal by dividing by 1,200. Entering 0.065 instead of 6.5 would mean a radically different rate.
• Loan amount versus home price: The principal is home price minus down payment, not the full purchase price. The formula assumes these two inputs describe the same purchase and currency.
• Rounding: The displayed payment is rounded to cents. A lender’s exact schedule may differ slightly because of its calculation conventions, payment dates, or final-payment adjustment.
• Fixed-rate assumption: A changing rate cannot be represented by one APR for the entire term. The output is not a forecast of a variable-rate loan.

Frequently Asked Questions

Does the estimated house payment include taxes and insurance?
No. It estimates principal and interest only. Property taxes, homeowners insurance, mortgage insurance, escrow, and other expenses must be estimated separately.

How does a larger down payment affect the monthly payment?
With the home price, APR, and term held constant, a larger down payment reduces the principal borrowed, which lowers the calculated monthly principal-and-interest payment.

Is the down payment the same as the total cash needed to buy a house?
No. The down payment is the portion of the purchase price not financed by the loan. Other costs may be due separately; this calculator does not estimate them.

Why is a lender’s payment different from this estimate?
The lender’s figure may include taxes, insurance, mortgage insurance, or other charges, or may use different loan details and payment conventions. Check its itemized figures and confirm the rate, term, and principal used.

Can I use this calculator for an adjustable-rate mortgage?
It can show a simple estimate for a chosen rate, but it assumes that rate stays fixed for the entire term. It does not model future rate adjustments or their effect on payments.

This result is an estimate for education, and the lender’s disclosure gives the exact figures.

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in price | Home price | $ | 350000 | 0.01 | 100000000
in down | Down payment | $ | 70000 | 0 | 100000000
in apr | Interest rate (APR) | % | 6.5 | 0.01 | 100
in yrs | Loan term | years | 30 | 0.0833 | 50
out pmt | Estimated monthly principal-and-interest payment | $ | (price - down) * (apr / 1200) / (1 - (1 + apr / 1200) ^ -(yrs * 12)) + 0 * sqrt(price - down) | 2
out int | Total interest over the term | $ | pmt * yrs * 12 - (price - down) | 2