You found a house at $400,000. You have $40,000 saved for a down payment. You open a mortgage calculator with PMI, enter 10% down and a 6.75% rate, and the payment comes back around $2,500 a month.
Then your loan officer sends an estimate: $3,030.
Neither number is fake. The first one skipped property taxes and homeowners insurance. The second is closer to what actually leaves your checking account. That gap is where buyers get bruised, and private mortgage insurance is usually the biggest single piece of it. The mortgage calculator number isn’t the number you’ll pay for exactly this reason, and PMI is the line item people most often miss.
What PMI Actually Is (It Isn’t Protecting You)
Private mortgage insurance pays the lender if you default. It does nothing for you. You write the check every month, and the lender collects if things go sideways.
Lenders require it when your down payment is under 20%, because a smaller down payment means a higher loan-to-value ratio, and higher LTV means more risk. On a conventional loan, that insurance typically covers 20% to 35% of the loan amount. Once you build enough equity, you stop paying it.
The cost isn’t a flat fee. It’s a percentage of your original loan amount, charged annually and then sliced into twelve monthly pieces. That percentage moves based on two things: how much you put down and what your credit score looks like.
How the Calculator Arrives at the PMI Line
Ballpark annual PMI rates on a conventional loan, by down payment and credit score:
- 20% down: zero. No PMI at all.
- 15% down, 760+ FICO: roughly 0.2% to 0.4% of the loan per year
- 10% down, 760+ FICO: roughly 0.3% to 0.5%
- 10% down, 680 FICO: roughly 0.6% to 0.9%
- 5% down, 680 FICO: roughly 0.9% to 1.2%
A Worked Example on a $400,000 House
Purchase price $400,000. Down payment 10%. Loan amount $360,000 at 6.75% fixed for 30 years.
- Principal and interest: $2,335
- PMI at 0.55% of $360,000: $1,980 a year, or $165 a month
- Estimated property tax: $400
- Homeowners insurance: $130
Total lands near $3,030. Put down $80,000 instead and the loan drops to $320,000, PMI disappears entirely, and the same house costs about $2,690 all in. You’d save $165 in insurance and roughly $260 in principal and interest every month. That’s $425 a month, or $5,100 a year, for $40,000 more cash down. Break-even on that extra money is under eight years. Run it through a PMI calculator and the result usually surprises people who assumed 20% down was out of reach.
The Expiration Date Most Calculators Ignore
On a conventional loan, PMI doesn’t follow you forever. Two thresholds matter.
80% Loan-to-Value: You Can Ask
Once your balance falls to 80% of the home’s original value, you can request removal in writing and the servicer has to respond. Many will want a current appraisal or a broker price opinion, plus a clean payment history. Approval isn’t automatic on the first request, and some servicers move slower than others, so keep records and follow up.
78% Loan-to-Value: It Comes Off on Its Own
Federal law requires servicers to terminate PMI automatically once your balance hits 78% of the original purchase price, as long as you’re current on payments. On that $360,000 loan at 6.75%, normal amortization gets you there in about eight and a half years. Add an extra $200 a month toward principal and you can pull that forward by more than two years.
FHA loans work differently. Put less than 10% down and the mortgage insurance premium stays for the life of the loan unless you refinance into a conventional loan later. Worth asking about before you pick an FHA lender over a conventional one.
Costs the PMI Line Still Hides
A calculator that includes PMI gets you closer to reality, but a few expenses still sit outside the number. A house payment calculator breakdown is a useful gut check on what’s missing:
- HOA dues, which can run $50 to $400 a month and never appear in mortgage math
- Upfront FHA mortgage insurance of 1.75% of the loan, paid at closing or rolled into the balance
- Closing costs of 2% to 5% of the purchase price
- Escrow cushion, since most lenders collect two months of taxes and insurance up front
- Maintenance, which averages about 1% of home value a year and shows up in no calculator at all
Ways to Reduce or Skip PMI
Twenty percent down is the clean solution. It’s also not realistic for everyone, and it isn’t the only path.
Piggyback loans. An 80/10/10 structure means a first mortgage at 80% LTV, a second mortgage for 10%, and 10% down. No PMI. The tradeoff is a second loan carrying a higher rate, so compare that interest against what PMI would have cost. Sometimes the piggyback wins. Often it doesn’t.
Lender-paid PMI. The lender covers the insurance and charges you a slightly higher interest rate. It feels free. It isn’t. The rate bump typically costs more over 30 years than PMI would have, especially if you plan to stay put.
Single premium PMI. You pay the entire insurance cost at closing, often at a discount. Good move if you have cash left after closing. Bad move if it drains your emergency fund.
Refinance once you have equity. If the home appreciated or you’ve paid the balance down, a refinance can wipe out PMI. Whether it’s worth it depends on closing costs, your new rate, and how long you’ll stay. A mortgage refinance calculator run through the break-even honestly will tell you more than any lender’s pitch.
Run the Payment Twice Before You Make an Offer
Pull up a mortgage calculator with PMI and run two scenarios on the same house: one at the down payment you have today, one at 20%. Look at the difference in the total monthly payment, not just the PMI line. Then look at what the extra cash would earn sitting in a high-yield savings account instead.
Sometimes 10% down and paying PMI for a few years is the right call. It gets you into a house sooner, and the insurance ends on a schedule you can predict and plan around. Other times, waiting six months to save another $20,000 saves more than it costs.
Either way, treat the calculator’s output as a starting point, not an answer. A home mortgage calculator that includes taxes, insurance, and PMI gets you close to the real figure. Your Loan Estimate closes most of the remaining gap. Compare the two line by line before you sign, and you’ll know exactly what that house costs you every month for the next thirty years.