Down Payment Calculator

Why the Down Payment Is Its Own Planning Problem

The down payment is unusual among homebuying costs because it's the one number that's entirely within your control on a timeline you set yourself. Your mortgage rate depends on the market, your closing costs depend on your state, but your down payment depends on how much you save and how long you're willing to wait — which makes it worth planning deliberately instead of just watching a savings account grow and hoping.

This calculator turns that vague hope into an actual date. Tell it your target home price, your down payment goal, what you've already saved, and what you can set aside each month, and it projects exactly when your balance crosses the goal line — accounting for the interest your savings earn along the way, which matters more than people expect over a multi-year timeline.

How to Use This Calculator

A few honest inputs make this far more useful than optimistic ones:

1. Target home price and down payment goal

Use a realistic price for the type of home and neighborhood you're actually considering, not an aspirational one. If you're unsure of your target percentage, start at 20% to see the PMI-free scenario, then try 10% or 5% to compare how much sooner you could buy — and what it costs you in PMI.

2. Current savings and monthly contribution

Be honest about what you can consistently set aside, not what you could theoretically save in a perfect month. A number you can actually sustain will give you a timeline you can actually trust.

3. Savings APY

This is one of the easiest levers to pull. Moving your down payment fund from a checking account (often near 0%) to a high-yield savings account (often 4%+) can shave real time off your goal — try both figures in the calculator to see the difference for yourself.

4. Read the PMI line carefully

If your down payment goal is below 20%, check the monthly PMI figure against the money you'd save by buying sooner rather than waiting to hit 20%. Sometimes buying earlier with PMI still wins financially; sometimes waiting is clearly better — the Rent vs Buy Calculator can help you weigh that against continuing to rent in the meantime.

The Math Behind Your Savings Timeline

The Down Payment Calculator figures out your target down payment amount, then projects how long it will take to reach it based on your current savings, monthly contributions, and the interest your savings earn along the way.

Down payment goal

Down Payment = Home Price × Down Payment %

Months to reach goal

Each month, your balance grows from interest on the existing balance plus your new monthly contribution, compounding until the goal amount is reached: Balance = Balance × (1 + (1+APY)^(1/12) − 1) + Monthly Savings. Converting the APY to its true equivalent monthly rate this way — rather than simply dividing by 12 — keeps the actual annual growth consistent with the APY you entered, since APY already accounts for compounding.

PMI impact (estimate only)

If your down payment is below 20% on a conventional loan, this calculator estimates PMI as a flat annual percentage of the loan amount, divided into a monthly cost, for as long as your down payment stays below 20%. It does not model your loan's amortization schedule, so it can't predict the exact date PMI would actually be removed as your balance pays down or the home appreciates — treat the PMI figure as a planning estimate, not a guaranteed cost or removal timeline.

Worked examples

Example A — a standard 20% goal. For a $420,000 home with a 20% down payment goal ($84,000), starting from $15,000 saved and adding $1,200/month at 4% APY, it takes about 51 months (4.3 years) to reach the full goal, with no PMI once you close.

Example B — a smaller down payment, faster timeline. The same $420,000 home with a 10% goal ($42,000) instead of 20%, starting from the same $15,000 and $1,200/month, reaches its goal in about 21 months (1.8 years) — roughly two and a half years sooner — but the resulting loan carries PMI until enough equity builds. Compare the monthly PMI cost against the value of buying that much sooner to see which path fits your priorities.

Tips for Best Results

• 💡 Every extra $1 down lowers PMI risk Crossing the 20% threshold eliminates PMI entirely on most conventional loans, which can save hundreds per month.
• 💡 Use a high-yield savings account Parking your down payment fund in a high-yield account rather than a checking account meaningfully speeds up your timeline.
• 💡 Automate the monthly contribution A separate automatic transfer on payday tends to outperform "saving what's left over" — consistency matters more than the exact amount.
• 💡 Revisit the plan if your target price changes Home prices in your target area can move while you save — rerun the numbers periodically rather than assuming your original goal still fits the market.

Common Mistakes to Avoid

• ⚠️ Common mistake: forgetting closing costs Your down payment isn't the only cash you'll need — budget an additional 2–5% of the home price for closing costs.
• ⚠️ Common mistake: assuming 20% is required Many loan programs allow far less down — but a smaller down payment usually means PMI and a higher monthly payment.

Frequently Asked Questions