1 You borrow the part you don’t pay up front
When you buy a home, you pay some of the price yourself. That’s the down payment. A bank lends you the rest. That borrowed money is your loan.
2 Interest is the price of borrowing
The bank doesn’t lend money for free. It charges interest, like a rental fee for using its money. Your rate, 7.4%, is the fee for a whole year. You pay every month, so we split it into 12 parts:
So in the very first month, the interest is 0.617% of what you owe: $585,000 × 0.617% = $3,607.50.
3 The payment is the same every month
You’ll make 360 payments (30 years × 12 months). A math formula finds the one amount that, paid every month, covers the interest and pays the loan down to exactly zero on the last payment. For your loan, that amount is:
Think of it like a bucket with a leak. Each month interest drips in, and your payment scoops out more than drips in. What’s left over shrinks the loan a little.
4 Where each payment goes changes over time
Every payment is split in two: the interest (the bank’s fee) and the principal (the part that actually shrinks your loan). At first, most of your payment is interest, because you owe so much. As the loan gets smaller, the interest gets smaller too, so more of each payment goes to paying it off.
Your payment starts sending more to the loan than to interest at payment #249, about 20 years and 8 months in.
5 What it adds up to
If you make every payment for the full 30 years and never pay extra:
That’s $585,000 to pay back what you borrowed plus $873,152 in interest. Most people sell or refinance before the end, so they pay less interest than this, and paying a little extra each month cuts it down a lot.
6 The other bills that come with a home
The loan payment isn’t the whole story. Most homeowners also pay these every month, usually bundled into the same payment:
| Loan (principal & interest) | from step 3 | $4,050 |
|---|---|---|
| Property tax | $650,000 × 1.9% a year ÷ 12 | $1,029 |
| Home insurance | $1,800 a year ÷ 12 | $150 |
| PMI (mortgage insurance) | about 0.5% of the loan a year ÷ 12 | $244 |
| HOA dues | none entered | $0 |
| All together | $5,473 a month |
Why PMI? When you put down less than 20%, the lender is taking a bigger risk, so you pay for insurance that protects them. It isn’t forever: it can come off once you owe 80% of the home’s value, about 8 years and 8 months in on this loan if you make regular payments. With 20% down, your loan payment would be $3,600 and there’d be no PMI.
Property taxes depend a lot on where you live, and insurance depends on the home. Look up your town’s tax rate.
For the curious: the actual formula
Banks use this formula to find the steady monthly payment (M):
M = P × r × (1 + r)n ÷ ((1 + r)n − 1)
- P = the loan: $585,000
- r = the monthly rate as a decimal: 0.006167
- n = number of payments: 360
Put those in and you get $4,050.42. The (1 + r)n part is what makes interest grow on itself over time; dividing by it spreads everything into equal payments.
Ways to make it smaller
- Put more down: a smaller loan means a smaller payment, and 20% down removes PMI. How long would that take to save?
- Get a lower rate: a better credit score usually means a lower rate. See what your score is worth.
- Look at lower-tax towns: the same price can cost hundreds less a month. Find towns by tax rate.
- Pay a little extra: even $100 more a month saves thousands in interest. Try the extra payment calculator.
Estimates for educational purposes only, not a loan offer. Your actual rate, taxes, insurance and PMI depend on your lender, your credit, the home and where it is. This week’s Freddie Mac average (30-yr fixed, week of Oct 8). Your rate may differ.