Most mortgage advice talks in generalities. This is a specific, worked example instead — a real $350,000 home, a real down payment, and the exact monthly number that results, calculated the same way our mortgage calculator and savings goal calculator compute it.
The setup
A $350,000 home, 10% down ($35,000), a 6.5% interest rate on a 30-year mortgage. 10% down is a realistic, common scenario — enough to be a meaningful down payment, but below the 20% threshold that avoids mortgage insurance, which is exactly the kind of detail worth seeing play out in real numbers rather than skipped over.
| Loan amount financed ($350,000 − $35,000) | $315,000.00 |
| Principal & interest | $1,991.01 |
| Property tax (est. 1.1% annually) | $320.83 |
| Home insurance | $125.00 |
| PMI (since down payment is under 20%) | $131.25 |
| Total monthly payment | $2,568.09 |
Why PMI shows up here, and what it actually costs
Because the down payment is 10%, not 20%, the lender requires private mortgage insurance — protection for the lender, not the buyer, in case of default. Here it adds $131.25 a month, or about $1,575 a year. This isn't a permanent cost: once enough of the loan is paid down to reach 20% equity, PMI can typically be removed, which is one real reason to track your loan balance over time rather than just set the payment and forget it.
What the "principal and interest" line actually hides
That $1,991.01 is a fixed number for the full 30 years, but what it's made of changes completely over time. In the first year, the overwhelming majority of each payment goes to interest, not principal — this is normal amortization behavior, not a red flag, and it's exactly why paying extra toward principal early in a mortgage saves more in total interest than the same extra payment made later. Over the full 30-year term, the total interest paid on this loan comes to $401,765.14 — more than the home's original price, which is the real, unglamorous math of what a 30-year mortgage costs when interest is included.
Saving the $35,000 down payment
Say $5,000 is already saved, with a goal of reaching the full $35,000 in two years, in a savings account earning 4% annually. Working backward through the same math our savings goal calculator uses:
| Already saved | $5,000.00 |
| Goal | $35,000.00 |
| Timeline | 2 years |
| Assumed rate | 4.0% annually |
| Required monthly contribution | $1,186.08 |
| Of which is interest earned | $1,534.06 |
That last line is worth sitting with: even over just two years, the interest earned on the growing balance covers more than a full month's worth of contributions on its own. The number that actually matters for planning is the $1,186.08 monthly contribution — that's the real, concrete target, not just "save more."
Try this with your own numbers
Every figure above came directly from real inputs into two of our tools. Run your own home price, down payment, and rate through the mortgage calculator to get your actual monthly payment, then use the savings goal calculator to work out what saving for your down payment actually requires per month, on your own timeline.