Down Payment Calculator: How Much Home Can You Buy?

How much down payment do you need?

On the defaults — a $400,000.00 home, 20% down, 6.5% for 30 years — the down payment is $80,000.00 ($400,000.00 × 20%), the loan is $320,000.00 ($400,000.00 − $80,000.00), the monthly payment is $2,022.62, and the total interest is $408,143.20 ($2,022.62 × 360 − $320,000.00). A 20% down payment is the traditional target because it usually avoids private mortgage insurance (PMI); put down less than 20% on a conventional loan and the lender usually requires PMI, which adds to the monthly cost; FHA loans allow as little as 3.5% down.

Five things about the model are worth stating plainly. First, the down payment is the home price times the percentage — $400,000.00 × 20% = $80,000.00. Second, the loan is the price minus the down payment — $400,000.00 − $80,000.00 = $320,000.00. Third, the monthly payment is the loan at the monthly rate over the term — $320,000.00 at 6.5% for 30 years = $2,022.62. Fourth, the total interest is the rounded payment times the number of months minus the loan — $2,022.62 × 360 − $320,000.00 = $408,143.20. And fifth, every extra point of down payment cuts the loan dollar-for-dollar, and the payment falls with it — the trade-off is cash today versus interest over 30 years; all listed in Accuracy & limitations.

The worked example, line by line

Setup: $400,000.00 home, 20% down, 6.5% rate, 30-year term.

Line 1 — the down payment. The down payment is $400,000.00 × 20% = $80,000.00.

Line 2 — the loan. The loan is $400,000.00 − $80,000.00 = $320,000.00.

Line 3 — the monthly payment. The monthly rate is 6.5% ÷ 1200 = 0.00541667 and the term is 360 months, so the payment is $2,022.62 a month.

Line 4 — the total interest. The total interest is $2,022.62 × 360 − $320,000.00 = $408,143.20.

Line 5 — the trade-off. Every extra point of down payment cuts the loan dollar-for-dollar — at 25% down the loan is $300,000.00 and the payment is $1,896.20, while at 10% down the loan is $360,000.00 and the payment is $2,275.44.

Every branch, checked

$600,000.00 home: Home price $600,000.00, 20% down, 6.5% for 30 years: down $120,000.00, loan $480,000.00, payment $3,033.93 a month, total interest $612,214.80 — a $600,000.00 home at 20% down needs $120,000.00 upfront and the payment rises to $3,033.93.

10% down: Home price $400,000.00, 10% down, 6.5% for 30 years: down $40,000.00, loan $360,000.00, payment $2,275.44 a month, total interest $459,158.40 — at 10% down the loan is $360,000.00, the payment is $2,275.44, and the total interest is $459,158.40.

3% down: Home price $400,000.00, 3% down, 6.5% for 30 years: down $12,000.00, loan $388,000.00, payment $2,452.42 a month, total interest $494,871.20 — at 3% down the loan is $388,000.00, the payment is $2,452.42, and the total interest is $494,871.20.

7.5% rate: Home price $400,000.00, 20% down, 7.5% for 30 years: down $80,000.00, loan $320,000.00, payment $2,237.49 a month, total interest $485,496.40 — at a 7.5% rate the same $320,000.00 loan costs $2,237.49 a month and $485,496.40 of interest.

15-year term: Home price $400,000.00, 20% down, 6.5% for 15 years: down $80,000.00, loan $320,000.00, payment $2,787.54 a month, total interest $181,757.20 — over 15 years the payment is $2,787.54 but the total interest falls to $181,757.20.

$250,000.00 home: Home price $250,000.00, 20% down, 6.5% for 30 years: down $50,000.00, loan $200,000.00, payment $1,264.14 a month, total interest $255,090.40 — a $250,000.00 home at 20% down needs $50,000.00 upfront and the payment is $1,264.14.

$500,000.00 home at 10% down: Home price $500,000.00, 10% down, 6.5% for 30 years: down $50,000.00, loan $450,000.00, payment $2,844.31 a month, total interest $573,951.60 — a $500,000.00 home at 10% down needs $50,000.00 upfront, the same as the $250,000.00 home at 20%.

The reverses, worked backwards

Home price so the down payment is exactly $50,000.00 (20% down): $250,000.00 — the exact price is 250000.0000. At the displayed $250,000.00 the down payment is $50,000.00, the loan is $200,000.00, the payment is $1,264.14, and the total interest is $255,090.40. The star is DOLLARS.

Down-payment percentage so the loan is exactly $300,000.00 (price $400,000.00): 25% — the exact percentage is 25.0000. At the displayed 25% the down payment is $100,000.00, the payment is $1,896.20, and the total interest is $382,632.00. The star is PERCENT.

Rate for a payment of exactly $2,000.00 on a $320,000.00 loan, 30 years: 6.40% — the exact rate is 6.3922%. At the displayed 6.40% the payment is $2,001.62 — $1.62 over the $2,000.00 target; at 6.39% the payment is $1,999.52 — $0.48 short. 6.40% is the first 0.01pp step that reaches the target. The star is PERCENT.

Smallest whole-year term with a payment of $2,500.00 or less (loan $320,000.00, 6.5%): 19 years. At 19 years the payment is $2,447.54; at 18 years the payment is $2,517.00 — not low enough. 19 years is the smallest whole-year term that gets the payment to $2,500.00 or less. The star is YEARS.

Home price so the loan is exactly $500,000.00 (20% down): $625,000.00 — the exact price is 625000.0000. At the displayed $625,000.00 the down payment is $125,000.00, the payment is $3,160.34, and the total interest is $637,722.40. The star is DOLLARS.

Smallest cent home price whose ROUNDED payment reaches $2,000.00 (20% down, 6.5%, 30 years): $395,526.06 — the exact price is 395526.0550. At the displayed $395,526.06 the down payment is $79,105.21, the loan is $316,420.85, the payment is $2,000.00, and the total interest is $403,579.15. At $395,526.05 the payment is $1,999.99. $395,526.06 is the smallest cent price whose rounded payment reaches $2,000.00. The star is DOLLARS.

What the defaults assume

The defaults are a $400,000.00 home, 20% down, a 6.5% rate, and a 30-year term — down payment $80,000.00, loan $320,000.00, payment $2,022.62, total interest $408,143.20. With a $600,000.00 home, Home price $600,000.00, 20% down, 6.5% for 30 years: down $120,000.00, loan $480,000.00, payment $3,033.93 a month, total interest $612,214.80 — a $600,000.00 home at 20% down needs $120,000.00 upfront and the payment rises to $3,033.93. With a 10% down, Home price $400,000.00, 10% down, 6.5% for 30 years: down $40,000.00, loan $360,000.00, payment $2,275.44 a month, total interest $459,158.40 — at 10% down the loan is $360,000.00, the payment is $2,275.44, and the total interest is $459,158.40. With a 3% down, Home price $400,000.00, 3% down, 6.5% for 30 years: down $12,000.00, loan $388,000.00, payment $2,452.42 a month, total interest $494,871.20 — at 3% down the loan is $388,000.00, the payment is $2,452.42, and the total interest is $494,871.20. With a 7.5% rate, Home price $400,000.00, 20% down, 7.5% for 30 years: down $80,000.00, loan $320,000.00, payment $2,237.49 a month, total interest $485,496.40 — at a 7.5% rate the same $320,000.00 loan costs $2,237.49 a month and $485,496.40 of interest. With a 15-year term, Home price $400,000.00, 20% down, 6.5% for 15 years: down $80,000.00, loan $320,000.00, payment $2,787.54 a month, total interest $181,757.20 — over 15 years the payment is $2,787.54 but the total interest falls to $181,757.20. With a $250,000.00 home, Home price $250,000.00, 20% down, 6.5% for 30 years: down $50,000.00, loan $200,000.00, payment $1,264.14 a month, total interest $255,090.40 — a $250,000.00 home at 20% down needs $50,000.00 upfront and the payment is $1,264.14. With a $500,000.00 home at 10% down, Home price $500,000.00, 10% down, 6.5% for 30 years: down $50,000.00, loan $450,000.00, payment $2,844.31 a month, total interest $573,951.60 — a $500,000.00 home at 10% down needs $50,000.00 upfront, the same as the $250,000.00 home at 20%. With a 0% down, Home price $400,000.00, 0% down, 6.5% for 30 years: down $0.00, loan $400,000.00, payment $2,528.27 a month, total interest $510,177.20 — 0% down leaves the full $400,000.00 as the loan, and the payment is $2,528.27. With a 100% down, Home price $400,000.00, 100% down, 6.5% for 30 years: down $400,000.00, loan $0.00, payment $0.00 a month, total interest $0.00 — 100% down means no loan, no payment, and no interest. With a $0.00 home price, Home price $0.00, 20% down, 6.5% for 30 years: down $0.00, loan $0.00, payment $0.00 a month, total interest $0.00 — a $0.00 home price means no down payment, no loan, and no payment. With a 0% rate, Home price $400,000.00, 20% down, 0% for 30 years: down $80,000.00, loan $320,000.00, payment $888.89 a month, total interest $0.00 — a 0% rate means the payment is the loan divided by 360 months, and the total interest is $0.00 by definition. With a $1,000,000.00 home, Home price $1,000,000.00, 20% down, 6.5% for 30 years: down $200,000.00, loan $800,000.00, payment $5,056.54 a month, total interest $1,020,354.40 — a $1,000,000.00 home at 20% down needs $200,000.00 upfront and the payment is $5,056.54. With a $150,000.00 home, Home price $150,000.00, 20% down, 6.5% for 30 years: down $30,000.00, loan $120,000.00, payment $758.48 a month, total interest $153,052.80 — a $150,000.00 home at 20% down needs $30,000.00 upfront and the payment is $758.48. With a 5% down, Home price $400,000.00, 5% down, 6.5% for 30 years: down $20,000.00, loan $380,000.00, payment $2,401.86 a month, total interest $484,669.60 — 5% down leaves a $380,000.00 loan and a $2,401.86 payment.

Output · formula · meaning

Who uses this

• The first-time buyer pricing a $400,000 home: they learn 20% down is $80,000.00, the loan is $320,000.00, and the payment is $2,022.62 a month — and they check the 3% branch to see what the minimum down payment costs them.
• The buyer stretching to a $600,000 home: they learn 20% down is $120,000.00 upfront and the payment is $3,033.93 — and they check the $395,526.06 reverse to see the most expensive home that still keeps the payment at $2,000.00.
• The buyer choosing between 10% and 20% down: they learn 10% down leaves a $360,000.00 loan and a $2,275.44 payment against $408,143.20 of interest at 20% down — and they check the 25% reverse to see the down payment that gets the loan to exactly $300,000.00.
• The buyer who needs the payment under $2,500.00: they learn 19 years is the shortest term that gets there — and they check the 6.40% reverse to see the rate that gets the payment to $2,000.00.

Accuracy & limitations

The math is first-principles: the down payment is the home price times the percentage divided by 100, the loan is the price minus the down payment, the monthly payment is the loan at the monthly rate over the term, and the total interest is the rounded payment times the number of months minus the loan — each rounded to cents half-up, and the total interest is $0.00 by definition at a 0% rate. What the model cannot do is price your actual mortgage: the payment shown is principal and interest ONLY — it does not include property tax, homeowners insurance, PMI, or HOA dues, which together can add hundreds of dollars a month; a 20% down payment is the traditional target because it usually avoids PMI, but put down less than 20% on a conventional loan and the lender usually requires PMI, which adds to the monthly cost; FHA loans allow as little as 3.5% down; the rate you actually get depends on your credit, the lender, and the day you lock; and a bigger down payment means more cash tied up in the house on day one. Use it to find the down payment, the loan, and the payment — then check the real tax, insurance, and PMI figures before you offer.

Frequently asked questions