$1,432/mo
Principal & Interest
At 4% interest over 30 years, a $300,000 mortgage runs approximately $1,432 per month in principal and interest. For a home priced at $375,000 with 20% down, or $300,000 with no down payment, this is the baseline P&I figure.
Factor in property taxes and homeowner's insurance — typically $300–$600/month — and expect total housing costs around $1,732–$2,032/month.
Calculate Your Exact Payment →These figures are based on a $300,000 loan at 4% over 30 years. Your actual loan amount, term, and rate will vary. Use the Mortgage Calculator to enter your specific details and get a tailored monthly payment.
At 4%, you'll repay about $1.72 for every $1 borrowed over 30 years. Roughly 42% of your total payments go toward interest — a noticeable jump from a 3% loan, where interest accounts for about 34%.
Here's how the same $300,000 loan looks across a range of interest rates:
| Interest Rate | Monthly P&I | Total Interest (30yr) | vs. 4% |
|---|---|---|---|
| 3.0% | $1,265 | $155,332 | −$167/mo |
| 4.0% | $1,432 | $215,609 | — |
| 5.0% | $1,610 | $279,767 | +$178/mo |
| 6.0% | $1,799 | $347,515 | +$367/mo |
| 7.0% | $1,996 | $418,527 | +$564/mo |
The jump from 4% to 7% costs an extra $564/month — that's $203,000 more in total interest over the loan's lifetime. Even a 1% increase from 4% to 5% adds $64,000 in long-run interest costs.
Want to see what these numbers look like at a different home price? Each page below includes full rate, down payment, and term comparisons.
Browse all 37 price points on the Mortgage & Real Estate hub.
At 4% interest over 30 years, a $300,000 mortgage costs about $1,432/month for principal and interest. Including property taxes and insurance, total monthly housing costs typically run $1,732–$2,032.
On a $300,000 loan at 4%, total interest over 30 years is approximately $215,609. Your total repayment comes to $515,609 — about 72% above the original loan amount in added interest.
Historically, 4% is a solid rate. The long-term average for 30-year fixed mortgages sits around 7–8%. Rates briefly touched 2.65% in 2021, but 4% remains well below the historical norm and saves significantly compared to 6–7% rates. If you're locked in at 4%, refinancing would likely increase your rate in the current environment.