A Down Payment Calculator

A down payment is not only the cash you hand over — it sets the loan-to-value ratio, and that ratio decides whether mortgage insurance attaches to every payment for years. Choosing between 10% and 20% down is therefore a cash decision and an insurance decision at the same time.

Purchase price($)Down payment(%)20% puts you at exactly 80% LTV and removes conventional PMI.Annual PMI rate(%)Typically quoted between 0.19% and 1.5% depending on credit and LTV band.

Down payment required

$45,000.00

Loan amount: $405,000.00
Loan-to-value ratio: 90.00%
Mortgage insurance per month: $168.75

Values update as you type. This calculator covers the single scenario its formula assumes — see Common Mistakes for what it leaves out.

The formula this calculator uses

Down Payment = Purchase Price x Down Payment Percentage

DP: Down payment in dollars
Price: Agreed purchase price of the property
p: Down payment as a decimal — 10% becomes 0.10
LTV: Loan amount divided by purchase price
PMI: Private mortgage insurance, required above 80% LTV on conventional loans

How to check the result by hand

1
Start from the price, not from the target monthly payment
Working backwards from an affordable payment hides the cost of a low down payment, because it bundles insurance and rate into one number. Anchor on price and let every other figure follow.
2
Multiply price by your down payment percentage
$450,000 x 0.10 = $45,000. Write percentages as decimals; leaving 10 in place produces a tenfold error.
3
Compute the loan and the LTV ratio
Loan is $450,000 - $45,000 = $405,000, and LTV is $405,000/$450,000 = 90%. That is above the 80% threshold, so insurance applies.
4
Price the insurance while it lasts
At a 0.50% annual premium on $405,000 the monthly cost is $168.75. Multiply by the number of months before the balance reaches 80% to see the total rather than treating it as a permanent cost.
5
Add closing costs and reserves separately
Appraisal, title, prepaid taxes and insurance, plus two to six months of payment reserves, are on top of the down payment. Budget the full cash-to-close figure, not just the deposit.

For worked examples, common mistakes and the limits of this formula, read the full How To Calculate A Down Payment page.