On a $300,000 mortgage at 6.5% over 30 years, your first monthly payment is about $1,896. Of that, $1,625 goes straight to the lender as interest. Only $271 chips away at what you actually borrowed. That ratio is the single most important thing to understand about a mortgage, and almost nobody spells it out before you sign.
The payment has four parts, not one
When people say "my mortgage payment," they usually mean PITI: principal, interest, taxes, and insurance. Lenders bundle these into one monthly number, which is why your payment rarely matches the clean figure a rate quote implies.
- Principal — the chunk that reduces your loan balance.
- Interest — the lender's fee for the money, charged on the balance you still owe.
- Taxes — property taxes, collected monthly and held in escrow, then paid to your local government once or twice a year.
- Insurance — homeowners insurance, also escrowed.
Two more can show up. PMI (private mortgage insurance) applies if you put down less than 20%. HOA dues apply if your home is in an association, and those are often paid separately rather than through the lender.
Here's how it stacks up on that $300,000 loan, assuming a $375,000 home with 20% down, property tax near the 1.1% national average, and typical homeowners insurance:
- Principal + interest: $1,896
- Property tax: ~$344 ($4,125/year)
- Homeowners insurance: ~$142 ($1,700/year)
- PITI total: ~$2,382
Taxes and insurance add roughly 25% on top of the loan payment itself. A quote that shows you only principal and interest is showing you about four-fifths of the real number.
Why the early years are almost all interest
Interest is charged on your remaining balance, so at the start — when you owe the most — the interest portion is huge. This is amortization: the payment stays the same every month, but its makeup shifts.
That first payment was $1,625 interest and $271 principal. Fast-forward to year 10 and the split has tilted toward principal; in the final years, nearly the whole payment reduces the balance. The math is front-loaded in the lender's favor, which has two real consequences:
- If you sell or refinance in the first few years, you've built very little equity through payments — most of what you paid was interest.
- Extra principal early is worth far more than extra principal later, because every dollar you knock off the balance stops accruing interest for the entire remaining term.
Paying an extra $200 a month on this loan from day one pays it off in about 23 years instead of 30 — close to seven years sooner — and cuts more than $100,000 in interest. You can see the exact effect by running the numbers in a Mortgage Calculator — it runs in your browser, so you're not handing your income and loan details to a lead-generation form.
A small rate change is not small
Rates get quoted in fractions of a percent, which makes them sound trivial. They aren't. On the same $300,000 loan:
- 6.5% → $1,896/month
- 7.0% → $1,996/month (+$100)
- 7.5% → $2,098/month (+$202)
A full point costs about $202 more every month — roughly $72,700 over 30 years. Even half a point runs around $36,000. The effect is so large because it compounds across 360 payments: a slightly higher rate applies to your whole balance, every month, for decades.
This is also why locking a rate matters, and why paying "points" (an upfront fee to buy the rate down) can pay off if you keep the loan long enough. Run both scenarios before deciding — the breakeven is usually a few years in, and if you'll move or refinance before then, the points are wasted.
PMI: what it costs and when it disappears
If you put down less than 20%, most conventional lenders require private mortgage insurance. It protects the lender, not you, and typically runs 0.5%–1.5% of the loan per year. On a $300,000 balance at 0.7%, that's about $175 a month — pure cost that builds no equity.
The good news: on conventional loans, PMI isn't forever. Under the federal Homeowners Protection Act, you can request cancellation once your loan-to-value hits 80% (you've paid the balance down to 80% of the original value), and the lender must automatically drop it at 78%. So PMI is a temporary surcharge on a smaller down payment, not a permanent one.
One important exception: FHA loans carry their own mortgage insurance (MIP), and on most FHA loans taken out today with a low down payment it lasts the life of the loan unless you refinance into a conventional mortgage. If you're comparing an FHA loan to a conventional one with PMI, that difference can matter more than the headline rate.
When the calculator isn't the whole story
A payment estimate is a starting point, not a quote. A few things it won't capture:
- Closing costs — usually 2%–5% of the loan, paid upfront, and not part of your monthly payment.
- Escrow drift — property taxes and insurance premiums rise over time, so your "fixed" payment on a fixed-rate loan still creeps up.
- APR vs. rate — the interest rate is the cost of borrowing; APR folds in lender fees and gives a truer comparison between offers. Two loans with the same rate can have different APRs.
- Adjustable-rate loans — an ARM's low intro rate resets later, and no fixed-payment calculation tells you what happens after that.
The headline rate is the number everyone shops on, but it's not the number that leaves your account. PITI, plus any PMI, plus rising escrow, is what you actually pay.
The one thing to take away
Before you commit, compute the full PITI — not just principal and interest — and check what an extra $100 to $200 a month toward principal does over the life of the loan. The early years are where those dollars do the most work, because they cut interest for every month that follows. Two minutes with a mortgage calculator will tell you more about what you can actually afford than any rate quote will.