Down Payment Calculator

How to Use the Down Payment Calculator

The deposit is the single biggest obstacle between most people and a first home, and it is also the most misunderstood. This calculator shows the amount you need, how long it will take at your current saving rate, and — the part that changes minds — what every common deposit level would cost you each month.

1. Enter the home price. Use the price of a property you would actually buy in your area, not a national average. If you are not sure what that is, the affordability calculator works it out from your income first.
2. Set the deposit percentage you are aiming for. Start at 20% because that is where mortgage insurance stops, then try lower figures and watch the payment column in the table.
3. Enter what you have saved and how much you add each month. Only count money genuinely earmarked for the purchase — a deposit fund raided for a holiday is not a deposit fund.
4. Set the mortgage rate you expect to be offered, so the payment figures at each deposit level are realistic rather than decorative.
5. Read the table. It prices every common deposit — 3%, 5%, 10%, 15%, 20% and 25% — with the time to save it and the monthly payment it produces, including mortgage insurance where it applies.

The tile marked PMI threshold is the one to watch if your target is below 20%. It shows exactly how much more you would need to cross the line where mortgage insurance disappears entirely.

Down Payment Formula

The deposit arithmetic is simple. The interesting part is what each level does to the payment.

Private mortgage insurance protects the lender, not you, and it is the reason 20% is treated as a magic number. It is charged monthly, adds nothing to your equity, and stops when the balance falls to 80% of the original value.

Example

A $380,000 home with $32,000 saved

1. Target deposit at 20%: 380,000 × 0.20 = $76,000.
2. Gap: 76,000 − 32,000 = $44,000. You are 42% of the way there.
3. At $1,200 a month: 44,000 ÷ 1,200 = 36.7 months, or just over three years.
4. Loan at that deposit: 380,000 − 76,000 = $304,000. At 6.5% over thirty years the payment is $1,921.49, with no mortgage insurance.
5. At 10% down instead, the loan is $342,000, the payment is $2,161.67, and PMI of $156.75 a month brings it to $2,318.42.
6. Waiting three years to reach 20% therefore saves $396.93 a month on the same house at the same rate.

The cost of waiting

That $396.93 monthly saving is real, but so is the cost of the wait. Three years of rent at $1,800 a month is $64,800 spent, and if prices rise 3% a year the same house costs $415,235 by the time you are ready — pushing the 20% deposit to $83,047 and moving the finish line further away as you approach it. This is the genuine dilemma of a rising market, and no calculator resolves it for you.

The middle path

Buying at 10% down now and overpaying by $400 a month reaches 80% loan-to-value in exactly four years, at which point the PMI comes off and the payment drops. You pay roughly $7,520 of mortgage insurance along the way, against $64,800 of rent avoided. Whether that trade is worth it depends entirely on what happens to prices — which is the one input nobody has.

Why 20% Is the Step That Matters

Every common deposit level on a $380,000 home, at 6.5% over thirty years.

Look at the jump between 15% and 20%. The payment falls by $268.13 for an extra $19,000 of deposit — far more than the other steps, because that is the step where mortgage insurance disappears. Between 20% and 25% the payment falls by only $120.10 for the same extra $19,000. Deposit money is not equally valuable at every level.

The other pattern worth noticing is that the low-deposit rows are not as far apart as people expect. Moving from 3% to 10% changes the payment by $180.32 a month. The difference between those options is mostly about risk and equity cushion rather than affordability — with a 3% deposit, a 5% fall in prices puts you in negative equity.

If the time-to-save column looks discouraging, the fastest lever is usually the monthly saving rather than the target. Raising the monthly figure from $1,200 to $1,600 cuts the wait from 36.7 months to 27.5 — nine months earlier, for $400 a month that the budget calculator may well be able to find.

Four Things to Sort Out Before the Deposit

Four things to sort out before the deposit itself.

Closing costs are separate. Fees, legal work and transfer taxes typically add 2% to 5% of the price on top of the deposit — around $15,000 on this house. Turning up with exactly the deposit and nothing else is the most common way a purchase falls apart in the final fortnight. The closing cost calculator prices them line by line.

Keep the emergency fund intact. Emptying your savings into a deposit and then meeting a broken boiler with a credit card undoes the whole benefit. Size the reserve with the emergency fund calculator and treat it as untouchable.

Where you keep the money matters. A deposit needed within three years belongs in cash or something equivalent, not in the stock market. The savings calculator will show what a decent interest rate adds — saving $1,200 a month from a $32,000 start at 4% earns about $6,960 of interest over the three years, nearly six months of saving handed to you.

Gifted deposits have rules. Most lenders accept family gifts but require a signed letter confirming the money is a gift rather than a loan, and many want to see it seasoned in your account for two or three months. Start that paperwork early rather than in the week of the application.

One habit that helps more than any of the above: automate the transfer on payday, to a separate account, before anything else moves. Deposit funds built from whatever happens to be left at the end of the month grow far more slowly than the arithmetic on this page suggests, because there is rarely anything left.

Once the deposit is in place, price the actual purchase with the mortgage calculator, which adds property tax, insurance and any mortgage insurance to the payments shown here.