How Mortgage Rates Work: What Sets Your Rate and What It Costs
From bond markets to your credit score: the forces behind mortgage rates and why one percentage point matters so much.
Key takeaways
- Mortgage rates are driven by long-term bond yields and central bank policy, plus the lender's margin.
- Your personal rate depends on your credit score, down payment, loan type and term.
- On a $300,000 30-year loan, the difference between 6% and 7% is about $197 a month and over $71,000 in total interest.
- Compare offers by APR and total cost, not by the headline rate alone.
For most people a mortgage is the largest loan they will ever take out. Because the balance is large and the term is long, small differences in the interest rate translate into large differences in cost. Understanding where rates come from helps you judge an offer and decide when and how to lock in.
What drives mortgage rates
Bond markets
Lenders fund mortgages with long-term money. In the US, 30-year fixed mortgage rates tend to move with the yield on 10-year Treasury bonds, because mortgages are bundled into securities that compete with Treasuries for investors. In other countries, swap rates or government bond yields play a similar role. When investors expect higher inflation or stronger growth, yields rise and mortgage rates follow.
Central banks
Central banks such as the Federal Reserve, the European Central Bank and the Bank of England set short-term policy rates. These directly affect adjustable-rate and tracker mortgages and influence fixed rates indirectly through expectations about future rates and inflation.
The lender's margin
On top of its funding cost, every lender adds a margin to cover risk, operating costs and profit. Margins differ between lenders, which is why shopping around can save you a meaningful amount.
What determines your personal rate
- Credit score: borrowers with stronger credit histories are offered lower rates.
- Down payment and loan-to-value (LTV): a larger down payment means less risk for the lender and usually a lower rate.
- Debt-to-income ratio: lenders check that your total debt payments fit your income.
- Loan type and term: fixed vs. adjustable, 15 vs. 30 years, government-backed vs. conventional loans.
- Property type and use: investment properties and second homes typically cost more than a primary residence.
Fixed vs. adjustable rates
A fixed-rate mortgage keeps the same rate for the entire term (common in the US) or for an initial period such as 2, 5 or 10 years (common in the UK and much of Europe). Your payment is predictable, and you are protected if rates rise.
An adjustable-rate mortgage (ARM) or variable/tracker mortgage starts with a rate that later adjusts in line with a reference rate. The initial rate is often lower, but payments can rise significantly. If you choose one, check the adjustment caps and make sure you could afford the payment at a much higher rate.
What one percentage point really costs
Monthly payments on a fully amortizing mortgage are calculated with the annuity formula. Here is a $300,000 loan (principal and interest only, excluding taxes and insurance):
| Rate | Term | Monthly payment | Total interest |
|---|---|---|---|
| 6.00% | 30 years | $1,798.65 | $347,515 |
| 7.00% | 30 years | $1,995.91 | $418,527 |
| 6.00% | 15 years | $2,531.57 | $155,683 |
One percentage point adds about $197 per month and roughly $71,000 over 30 years. Choosing a 15-year term at the same 6% raises the monthly payment by about $733 but cuts total interest by more than half. The rates in this table are examples, not current market rates.
Points, fees and APR
Some lenders let you pay discount points upfront to lower your rate. One point usually costs 1% of the loan amount. Paying points makes sense only if you keep the mortgage long enough for the lower payments to outweigh the upfront cost; divide the cost of the points by the monthly saving to find your break-even point in months.
The APR includes the interest rate plus points and most lender fees, so it is a better basis for comparing offers. Also look at the closing costs that are not included in the APR, such as appraisal, title and government fees.
Rate locks and timing
Once you have an accepted offer on a home, you can usually lock your rate for a period, often 30 to 60 days, while the loan is processed. A lock protects you if rates rise before closing. Trying to time the market perfectly rarely works; focus on what you can control: your credit, your down payment and comparing several lenders.
How to get a better mortgage rate
- Improve your credit and pay down revolving debt a few months before applying.
- Save for a larger down payment to reduce your loan-to-value ratio.
- Get quotes from several lenders on the same day and compare APR and closing costs.
- Consider a shorter term if the payment fits your budget.
- Ask about every fee and negotiate; lender charges are often flexible.
Explore more in our mortgage and home financing guides, or learn how loan rates and APR work in general.
