The short answer
On a $400,000 home with 20% down ($80,000) at 6.5% over 30 years, principal and interest is $2,022.62 a month. Add $400 in property tax and $100 in insurance and the full PITI payment is $2,522.62. Total interest paid over the full 30 years is $408,142.36 — more than the loan itself.
Key takeaways
- $320,000 loan at 6.5% over 30 years: $2,022.62/month P&I, $2,522.62 full PITI with typical tax and insurance.
- Total interest over 30 years is $408,142.36 — more than the $320,000 borrowed.
- Switching to a 15-year term on the same loan raises the payment to $2,787.54/month but cuts total interest to $181,757.84, saving $226,384.52.
- Dropping to 10% down adds $150/month in PMI on top of a larger $2,275.44 P&I payment — PMI disappears once equity reaches roughly 20%.
What actually makes up your payment (PITI)
On a $400,000 home with 20% down, the $320,000 loan at 6.5% over 30 years breaks into four pieces:
Principal & Interest: $2,022.62
Property Tax ($4,800/yr): $400.00
Home Insurance ($1,200/yr): $100.00
Total Monthly Payment: $2,522.62
Principal and interest is fixed for the life of a fixed-rate loan, but taxes and insurance typically rise over time and are usually collected through an escrow account as part of one combined bill — which is why your payment can increase even on a "fixed-rate" mortgage.
15-year vs 30-year: the real trade-off
On the same $320,000 loan at 6.5%, the term alone changes both the monthly payment and the total interest dramatically:
| 30-Year | 15-Year | |
|---|---|---|
| Monthly P&I | $2,022.62 | $2,787.54 |
| Total interest | $408,142.36 | $181,757.84 |
The 15-year loan costs $764.92 more per month but saves $226,384.52 in interest — nearly $300 saved in interest for every extra $1 paid monthly. The right choice depends on whether the higher payment fits comfortably in the budget, since the 15-year term offers no flexibility to pay less in a tight month the way voluntary extra payments on a 30-year loan would.
PMI: the cost of a smaller down payment
Dropping the down payment from 20% to 10% on the same $400,000 home increases the loan to $360,000 and adds PMI:
Loan amount: $360,000 (vs $320,000 at 20% down)
Monthly P&I: $2,275.44 (vs $2,022.62)
PMI at 0.5% annually: $150.00/month
PMI is calculated on the loan balance and typically continues until the loan balance drops to about 78–80% of the original home value, at which point it can usually be requested for removal — it isn't a permanent cost, but it is a real one until equity catches up.
Related calculators
- Mortgage Amortization Calculator — see the full month-by-month principal and interest breakdown.
- House Affordability Calculator — work from income to find a home price that fits your budget.
- Refinance Calculator — check whether a new rate is worth the cost of refinancing later.