5 Factors
Drive Your Payment
Your monthly mortgage payment is determined by five things: loan amount, interest rate, loan term, down payment, and property taxes + insurance. Change any one of these and your payment shifts — sometimes by hundreds of dollars per month.
Understanding how each factor works helps you make better decisions about what to buy, how much to put down, and which loan terms to choose.
Calculate Your Mortgage Payment →The fastest way to understand how each factor affects your payment is to adjust the inputs and watch the number change. Our Mortgage Calculator lets you modify rate, term, loan amount, and down payment in real time.
Try changing one variable at a time to see how much each factor moves the payment.
Open Mortgage Calculator →The loan amount is the home price minus your down payment. It's the largest single driver of your monthly payment — a bigger loan means a bigger payment, proportionally.
| Home Price | Down Payment | Loan Amount | Monthly P&I (7%, 30yr) |
|---|---|---|---|
| $250,000 | 20% ($50K) | $200,000 | $1,331 |
| $350,000 | 20% ($70K) | $280,000 | $1,863 |
| $500,000 | 20% ($100K) | $400,000 | $2,661 |
Every $50,000 in additional loan amount adds roughly $333/month at 7%.
The interest rate is the single most powerful lever per unit change. Small rate differences create large payment swings — and massive differences in total interest over the life of the loan.
| Rate | Monthly P&I ($300K, 30yr) | Total Interest Paid |
|---|---|---|
| 5.0% | $1,610 | $279,767 |
| 6.0% | $1,799 | $347,515 |
| 7.0% | $1,996 | $418,527 |
| 8.0% | $2,201 | $492,467 |
A 1% rate increase on a $300K loan adds ~$200/month and costs $70,000+ in additional interest over 30 years.
The loan term determines how many years you have to repay. A shorter term means higher monthly payments but dramatically less total interest. See our full 15-year vs. 30-year comparison.
$300K at 7% — higher monthly
$300K at 7% — lower monthly
Roughly 55% less total interest
Your down payment directly reduces the loan amount and, if it reaches 20%, eliminates private mortgage insurance (PMI).
| Down Payment | Loan Amount ($350K home) | Monthly P&I (7%, 30yr) | PMI? |
|---|---|---|---|
| 3.5% ($12,250) | $337,750 | $2,247 | Yes (+$170–$310) |
| 10% ($35,000) | $315,000 | $2,095 | Yes (+$130–$240) |
| 20% ($70,000) | $280,000 | $1,863 | No |
Going from 3.5% to 20% down on a $350K home saves $384/month in P&I plus eliminates $170–$310/month in PMI.
Your lender collects property taxes and homeowner's insurance as part of your monthly payment (the "TI" in PITI). These vary significantly by location.
These costs are often underestimated. A $350K home at 7% with 20% down has a $1,863 P&I payment, but total PITI is typically $2,400–$2,900/month.
Starting from a baseline of a $300,000 home, 20% down, 7% rate, 30-year term ($1,597/month P&I), here's what happens when you change one variable:
| Change Made | New Payment | Difference |
|---|---|---|
| Baseline (20% down, 7%, 30yr) | $1,597 | — |
| Rate drops to 6% | $1,439 | −$158/mo |
| Rate rises to 8% | $1,761 | +$164/mo |
| Down payment drops to 5% | $1,896 | +$299/mo (+PMI) |
| Home price rises to $400K (20% down) | $2,129 | +$532/mo |
| Term changes to 15 years | $2,157 | +$560/mo |
Each row changes only one factor. In reality, these compound — a higher price and a higher rate together push the payment much further.
A lower monthly payment doesn't always mean a cheaper mortgage. Longer terms and smaller down payments reduce monthly costs but increase total interest paid.
$240K loan at 7% — $1,597/mo
$240K loan at 7% — $2,157/mo
Saved by choosing 15yr term
The 30-year mortgage costs $560 less per month but $187,000 more over the life of the loan. Understanding this tradeoff is essential. See the full breakdown in our 15-year vs. 30-year comparison.
See how these factors play out at different price points. Each page includes rate comparisons, down payment tables, and 15-year vs. 30-year breakdowns.
Browse all 37 price points from $100K to $1M on the Mortgage & Real Estate hub.
The loan amount (home price minus down payment) is the largest absolute driver — a bigger loan always means a bigger payment. But the interest rate has the most impact per unit change. A 1% rate increase on a $300K loan adds ~$200/month and $72,000+ in total interest over 30 years.
They affect different things. Home price sets the base loan amount — every $50K adds ~$333/month at 7%. Interest rate determines the cost of borrowing — each 1% adds ~$200/month on a $300K loan but compounds to $70,000+ over the full term. For total cost, rate often matters more. For monthly payment, loan amount usually matters more.
A larger down payment reduces the loan amount, which directly lowers your monthly P&I. On a $400K home, putting 20% down instead of 5% reduces the loan by $60,000, saving roughly $400/month. Reaching 20% also eliminates PMI, saving another $150–$300/month. Use the mortgage calculator to see the exact impact for your scenario.
With a fixed-rate mortgage, your principal and interest (P&I) portion stays the same. But your total monthly payment can change due to escrow adjustments. Common causes: property tax reassessment (values went up), homeowner's insurance premium increase, PMI being added or removed, or a shortage in your escrow account from the prior year. Your lender recalculates escrow annually.
A full monthly mortgage payment includes PITI: Principal (repaying the loan balance), Interest (cost of borrowing), Taxes (property tax collected via escrow), and Insurance (homeowner's insurance). If your down payment is below 20%, PMI (private mortgage insurance) is also included, adding $100–$400/month.