Perclo
Every down payment scenario. One clean view.
Type in a home price. Perclo shows 3%, 5%, 10%, and 20% down on one screen, with the monthly payment, PMI cost, and total cash you need at closing for each one.
The amortization formula behind every column
The monthly principal and interest payment uses the standard fixed-rate amortization formula:
M = P x [ r(1+r)^n ] / [ (1+r)^n - 1 ]P is the loan principal (home price minus down payment). r is the monthly rate (APR divided by 12). n is the number of monthly payments, 360 for a 30-year fixed. For a $380,000 loan at 7.0%, r = 0.00583, n = 360, and (1+r)^n is 8.116. Plug those in: M = 380000 x (0.00583 x 8.116) / 7.116 = $2,528.27.
That's the Monthly P&I row. Perclo recomputes it four times, once per scenario, with only P changing. Rate and term stay constant across columns so the comparison stays clean. Flex the term to 15 years or buy down the rate and you need a different tool, because every column would shift at once.
The formula assumes a fixed rate for the life of the loan. ARMs, balloons, and interest-only loans need different math. Perclo will give you the wrong answer for any of them.
PMI rates by LTV band: where the numbers come from
PMI is annual, expressed as a percentage of the loan amount, then divided by 12. The percentage depends almost entirely on loan-to-value ratio and credit score. Perclo uses national-average rates by LTV band:
| Down payment | LTV at origination | Annual PMI rate (avg) | Monthly cost on $380k loan |
|---|---|---|---|
| 3% | 97% | 0.85% | $269 |
| 5% | 95% | 0.65% | $206 |
| 10% | 90% | 0.50% | $158 |
| 15% | 85% | 0.40% | $127 |
| 20% | 80% | none | $0 |
These are midpoints. The MGIC and Radian rate cards I pulled while building Perclo span roughly 0.55% to 0.85% at 95% LTV depending on credit score, and a 740 FICO sits near the middle of that range. Below 680 the spread widens and PMI can run 1.2% or higher. Perclo doesn't ask for credit score. That would imply a precision the rest of the calculation can't match, and it would push the page toward the lead-capture pattern I'm trying to avoid.
The 0.30% floor and 1.5% ceiling you see in most explainers are real but rare. Most conventional loans land in the four bands above.
The 78% LTV rule and how removal year is calculated
The Homeowners Protection Act of 1998 (12 U.S.C. § 4901) requires lenders to automatically cancel borrower-paid PMI on most conventional loans when the loan balance reaches 78% of the original purchase price, based on the amortization schedule. You can request cancellation at 80% LTV, though the lender can require an appraisal at your expense.
To estimate the removal year, Perclo walks the amortization table month by month and finds the first month where remaining principal divided by the original home price hits 0.78 or less. For 5% down on a $400,000 home at 7.0%, that lands in year 8 or 9. For 10% down, year 4 or 5. At 20% down, LTV starts at 80% and PMI never applies.
The denominator is the original purchase price, not current market value. Appreciation doesn't accelerate automatic removal, though it can support a manual cancellation request backed by an appraisal. Extra principal payments do accelerate it. Perclo assumes scheduled monthly payments only.
Closing cost estimate: what the 3% baseline includes and misses
Closing costs typically run 2% to 5% of the loan amount. Perclo uses 3% because that's the midpoint of what I paid on three home purchases in three states, and it matches the CFPB's 2024 data for conventional purchases under $500,000.
The 3% covers lender origination fees, title insurance (lender and owner policies), settlement and escrow fees, recording fees, the appraisal, the credit report, and prepaids (first year of homeowners insurance plus property tax and interest escrow funded to closing).
What 3% doesn't cover, and where Perclo will therefore understate: discount points (each is 1% of the loan, paid to buy down the rate), HOA transfer fees and capital contributions, surveys, pest inspections, jumbo-loan add-ons, and out-of-pocket inspections paid before closing.
On a $400,000 home, the 3% baseline produces these total-cash numbers: $23,640 at 3% down, $31,400 at 5%, $50,800 at 10%, and $89,600 at 20%. That's what your savings account needs to see.
Assumptions baked in and when not to trust the output
Five things Perclo holds constant that real loans don't.
The rate. Perclo defaults to a recent national-average 30-year fixed. Real rate locks vary by lender, lock period, and credit profile.
The PMI premium. National-average rates by LTV band. Your actual quote depends on credit score, debt-to-income, loan amount, occupancy, and property type. A condo or investment property carries a surcharge.
The closing-cost percentage. 3% flat. High-tax states like New York and Illinois often run higher. No-tax states like Washington often run lower.
Property tax and homeowners insurance. Not included. The Monthly P&I number is principal and interest only. Real PITI typically adds another $300 to $900 per month depending on location and home value, collected in escrow.
HOA dues. Not included.
Use Perclo to compare scenarios, not to underwrite the loan. The output is precise enough to choose between 5% and 10% down, or to see what PMI costs per month. It is not precise enough to be the only number you bring to the closing table.
Frequently asked questions
How much will PMI add to my monthly mortgage payment?
PMI typically adds between $80 and $300 per month on a conventional loan, depending on your loan-to-value (LTV) ratio and credit score. Annual PMI rates run from about 0.3% to 1.5% of the loan amount, divided into 12 monthly payments. A higher LTV (3% or 5% down) lands at the upper end of that range; a lower LTV (10% down) sits closer to the bottom. Perclo shows the exact monthly PMI cost in dollars for each down payment scenario using national-average rates by LTV band, so you see the number rather than a generic 'PMI required' flag.
How much cash do I actually need to buy a house?
Total cash at closing is your down payment plus closing costs. Closing costs typically run 2–5% of the loan amount and cover lender fees, title insurance, escrow, recording, and prepaids. On a $400,000 home with 10% down, that means about $40,000 in down payment plus roughly $10,800 in closing costs (3% baseline) — so about $50,800 in cash on closing day. Perclo combines both into one 'Total Cash Needed' number per scenario, so you can see what your savings account actually needs to hold for each down payment choice.
Should I put 3%, 5%, 10%, or 20% down on a house?
It is a trade-off between upfront cash and ongoing monthly cost. 20% down avoids PMI entirely and gives the lowest monthly payment, but requires the most cash at closing. 3% or 5% down gets you into the home with far less saved, but adds PMI (roughly $80–$300/month) until you reach 78% LTV, plus a higher principal and interest payment because you are financing more. 10% down is the middle ground — moderate upfront cash, moderate PMI, and PMI typically drops off in 4–6 years. Perclo shows all four scenarios side by side with the exact monthly and total-cash numbers, so you compare actual dollars rather than guessing.
When will PMI be removed from my mortgage?
On a conventional loan, the lender is legally required to remove PMI automatically when your loan-to-value (LTV) ratio reaches 78% of the original home value, based on the amortization schedule. You can also request cancellation once you hit 80% LTV. With 5% down, that typically takes 8–10 years of regular payments. With 10% down, it usually drops off in 4–6 years. With 20% down, PMI never applies. Perclo flags the 78% threshold for each scenario so you can see roughly when PMI stops adding to your monthly payment.
Is there a down payment calculator that does not require my email or push a lender?
Yes. Perclo runs entirely in your browser. There is no sign-up, no email capture, no 'talk to a lender' pop-up, and no lead form. All the math runs client-side, no data leaves the page. Most major calculators (Bankrate, NerdWallet, Rocket Mortgage, Zillow) treat the calculator as a lead-generation tool that funnels you to lenders or rate quotes. Perclo is free and ad-supported instead — the only thing it asks for is a home price.
What is the total cash needed at closing on a $400,000 home?
On a $400,000 home with a 3% closing-cost baseline, total cash at closing depends on your down payment: 3% down is about $12,000 + $11,640 = $23,640. 5% down is $20,000 + $11,400 = $31,400. 10% down is $40,000 + $10,800 = $50,800. 20% down is $80,000 + $9,600 = $89,600. Perclo computes this for any home price and shows all four scenarios side by side, so you can match the cash number to what you actually have saved.
How is PMI calculated for a conventional loan?
PMI is calculated as an annual percentage of the loan amount, then divided into 12 monthly payments. The percentage depends primarily on loan-to-value (LTV) ratio: about 0.55–0.85% for 95% LTV (5% down), 0.40–0.65% for 90% LTV (10% down), and 0.30–0.50% for 85% LTV (15% down). Credit score also matters — sub-680 scores can push rates higher. Perclo uses national-average rates per LTV band to estimate the monthly dollar cost for each scenario.
Is it better to put 20% down or invest the difference?
Mathematically, if you can earn a higher long-term return investing the difference (historically 7–10% in equities) than your mortgage rate plus PMI cost (currently around 6.5–8%), investing wins. But PMI adds real monthly cash flow drag and a higher loan balance means more total interest paid. The practical answer often comes down to whether you have a stable emergency fund left after a smaller down payment. Perclo shows the actual monthly payment difference and total cash at closing for each scenario so you can plug your own numbers into the math.
No sign-ups. No lead forms.
Perclo is free and ad-supported. There are no accounts and no “talk to a lender” pop-ups. We use PostHog for anonymous usage analytics (page views, basically) and that's it. Details are in the Privacy Policy.
Estimates only. PMI rates are national averages by LTV band. Closing costs use a 3% baseline. Your actual numbers will vary by lender, credit score, and location. This is not financial advice.