$400,000 mortgage at 8%: monthly payment over 30 and 15 years
At 8%, a $400,000 mortgage amortizes at $2,935.06 a month over 30 years and $3,822.61 over 15. This page lays out the consequences of that rate on that balance, all computed: interest paid, equity built, when PMI ends, and the cost of paying late.
| 30-year fixed | 15-year fixed | |
|---|---|---|
| Monthly principal & interest | $2,935.06 | $3,822.61 |
| Total interest over the term | $656,621 | $288,070 |
| Total paid (principal + interest) | $1,056,621 | $688,070 |
| Interest as a share of total paid | 62% | 42% |
Principal and interest only. Property taxes, homeowners insurance, mortgage insurance and HOA dues are added to the actual payment. Rates shown are for the arithmetic, not an offer; see 30-year vs 15-year for how to choose.
Where the payments go: the 30-year amortization
Early payments are mostly interest: $31,879 of year one’s $35,221 goes to the lender as interest and $3,341 to your balance. The balance below shows the curve.
| After | Remaining balance | Paid down |
|---|---|---|
| 5 years | $380,279 | $19,721 |
| 10 years | $350,899 | $49,101 |
| 15 years | $307,126 | $92,874 |
| 20 years | $241,912 | $158,088 |
| 25 years | $144,752 | $255,248 |
PMI tipping points: 80% and 78%
For a borrower who put less than 20% down, the question is when the balance hits 80% and 78% of the original value. Without extra principal or a new appraisal, this loan gets there in:
| Starting LTV | Home value | 80% (request) | 78% (automatic) |
|---|---|---|---|
| 97% | $412,371 | month 152 | month 163 |
| 95% | $421,053 | month 142 | month 154 |
| 90% | $444,444 | month 112 | month 127 |
Extra principal payments or a new appraisal showing appreciation can bring cancellation forward — see PMI removal. FHA mortgage insurance follows different rules.
What a late payment costs
Most mortgages charge a late fee of 4% to 5% of the principal-and-interest payment after a 15-day grace period (state caps vary): on this loan, about $117.40 to $146.75. The costlier consequence comes at day 30, when the servicer may report the payment late to the credit bureaus — a mark that stays seven years. Before it happens: the first 72 hours after a missed payment.
The formula
M = P × r(1 + r)n ÷ ((1 + r)n − 1), where P = $400,000, r = 8% ÷ 12 = 0.6667% per month, n = 360 (30 years) or 180 (15 years).
The balance after k payments is P(1 + r)k − M((1 + r)k − 1) ÷ r; total interest is M × n − P. No rounding beyond the displayed cents.
Frequently asked questions
What is the monthly payment on a $400,000 mortgage at 8%?
$2,935.06 a month for principal and interest on a 30-year fixed loan, or $3,822.61 on a 15-year fixed loan. Property taxes, homeowners insurance, mortgage insurance and any HOA dues are added on top and typically raise the total payment by 25% to 50%.
How much interest will I pay on a $400,000 loan at 8%?
$656,621 over 30 years, or $288,070 over 15 years, if every payment is made as scheduled with no extra principal. In the first year of the 30-year loan, about $31,879 of your $35,221 in payments is interest and $3,341 reduces the balance.
When can I cancel PMI on a $400,000 loan at 8%?
By the regular schedule alone, a loan that started at 95% of the home’s value reaches 80% loan-to-value in month 142 (when you may request cancellation) and 78% in month 154 (automatic cancellation). Extra principal payments or an appraisal showing appreciation can move that earlier.
Same amount, other rates: 5% · 6% · 7%. Same rate, other amounts: $150,000 · $200,000 · $250,000 · $300,000 · $350,000 · $500,000 · $600,000 · $800,000. All tables.