See principal, interest, taxes, insurance and PMI — then what the loan really costs over 30 years. Preloaded with Idaho averages — edit any field to match your situation.
Total monthly payment
$3,004
Principal, interest, taxes, insurance, PMI and HOA combined.
Removable at 20% equity.
Over 30 years.
Principal and interest is $2,510, which is 84% of the total. The remaining $494 covers property tax, insurance, PMI — costs that never build equity. Over 30 years you would pay $512,630 in interest on a $391,000 loan.
Because your down payment is under 20%, you pay private mortgage insurance that protects the lender, not you. At your current payment schedule the balance reaches 80% of the purchase price around month 58 (4 years, 10 months in), at which point you can request removal in writing. Lenders are required to cancel it automatically at 78%, but they will not do it early unless you ask.
Adding $200 of principal monthly would clear the loan in 24 years, 3 months rather than 30 years. Because the payment is fixed, every additional dollar reduces the balance that future interest is calculated on — which is why small extra payments early are worth far more than large ones later.
Fifteen-year mortgages typically price about half a point below 30-year loans. At 6.15% your payment would be $3,331 — $821 more each month — but total interest drops from $512,630 to $208,625. If the higher payment would strain your budget, taking the 30-year loan and voluntarily overpaying captures most of the saving while keeping the lower payment as a safety valve.
Compare loan termsA lender will approve you based on debt-to-income ratios that ignore childcare, commuting and retirement saving. Before committing to $3,004 a month, run the affordability calculator with your real budget — and compare against renting if you might move within five years.
Home affordability calculatorIdaho has an effective property tax rate of about 0.56% of home value, which on the statewide median price of $462,000 works out to roughly $216 a month before you touch principal or interest.
Homeowners insurance averages about $1,200 a year here, or $100 a month. Homeowner's exemption removes a large slice of assessed value.
The top marginal state income tax rate is 5.7%, which reduces take-home pay and so lowers the payment a lender will approve. The calculator above starts from these statewide figures — replace them with your actual county's rate and a real insurance quote as soon as you have them.
State figures are statewide averages used as starting values for the calculator. They are estimates for modeling only — not quotes, appraisals or tax advice. Your county, city, lender and insurer will differ. Edit any input to match your situation.
Using the 28% rule, roughly $2,333 a month toward housing, which at 6.65% with 15% down supports a home in the $330,000–370,000 range depending on your property tax rate and insurance costs. That is a ceiling rather than a target — it assumes no childcare, modest other debt and stable income. Many buyers on $100,000 are more comfortable in the $280,000–320,000 range, which leaves room to keep saving for retirement.
Good is relative to the current rate environment rather than any fixed number. What you can control is your position within the available range: a credit score above 740, a down payment of 20% or more, a debt-to-income ratio under 36%, and quotes from at least three lenders. That spread commonly covers 0.5 percentage points, which on a $400,000 loan is over $45,000 across 30 years.
Twenty percent eliminates PMI and secures better pricing, which is a guaranteed return. Keeping cash invested might earn more but might not. The stronger argument for a smaller down payment is timing — if reaching 20% takes three more years while prices and rents rise, the delay often costs more than the PMI would have. Whatever you choose, keep your emergency fund intact; a down payment that empties your savings turns a home into a liability.
It applies 0.55% of the loan amount annually whenever the down payment is under 20%, which sits in the middle of the typical 0.3%–1.5% range. Your actual rate depends on credit score, loan-to-value ratio and loan type — a 760 score with 15% down lands near the bottom of that range, while a 640 score with 5% down lands near the top. Your Loan Estimate will show the exact figure.
Compare the mortgage rate to your realistic after-tax investment return. At rates above roughly 6.5%, extra principal is competitive with expected equity returns and carries no risk. Below about 5%, investing usually wins over long horizons. The non-financial consideration matters too: a paid-off home substantially lowers your required income in retirement, which has value that a spreadsheet does not capture.
No — it models the ongoing monthly payment. Closing costs are a separate one-time expense of roughly 2–5% of the purchase price, covering origination, appraisal, title insurance, recording fees and prepaid escrow. On a $425,000 home that is typically $8,500–21,000, due at closing and separate from your down payment.
What usually comes next.
Two answers: what a lender will approve, and what your budget can genuinely sustain.
Buying wins eventually in most markets. This finds the year it starts winning in yours.
A lower rate is not automatically a win. This shows what restarting the clock costs.
Utilization is 30% of your FICO score and has no memory. It can improve in one billing cycle.
Sized on essential expenses and your actual risk profile — not a generic three-to-six months.
A complete first-time home buyer guide for the US: what to save, how pre-approval works, what closing costs cover, and the mistakes that cost the most.
Updated January 15, 2026
Work out how much house you can afford using the 28/36 rule, your actual budget, and the costs lenders ignore. Includes salary-by-salary examples.
Updated January 15, 2026
How mortgage rates are determined, what moves them, and the six factors that decide whether you get the advertised rate or half a point above it.
Updated January 15, 2026
Part of the mortgage hub.