Your mortgage rate is not one number decided in a back room; it is the sum of a bond market, your credit profile, the loan type you choose, and how you manage the rate lock. Understand those four pieces and you stop guessing at financing and start planning it. As a loan officer with more than 23 years of origination experience, I walk buyers through this every week, and the biggest mistake I see is obsessing over a fraction of a percent on the rate headline while ignoring the loan structure that changes the actual payment by hundreds of dollars.
This guide breaks down how rates are set, fixed versus adjustable products, conventional versus FHA, what lenders look for, and how rate locks work, with real numbers attached throughout. For a side-by-side program comparison, my FHA vs conventional vs VA answer is a good companion read.
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Stop Focusing on Interest Rates! 5 Ways to Lower Your Mortgage
Patrick shows why your payment is a stack, not a single number, and the five levers that lower it more than a quarter-point rate drop.
Watch the videoHow Mortgage Rates Are Set
Mortgage rates track long-term bond yields, most closely the 10-year Treasury, not the Federal Reserve's short-term rate, though Fed policy moves both. When bond investors demand higher returns, mortgage rates climb; when bonds rally, rates fall. That is why mortgage rates can move between the time you apply and the time you lock: market moves a few hundredths of a point happen every day.
On top of the market rate, your loan officer layers in your specific pricing: your credit score, down payment, loan type, and loan size all affect the rate you are quoted. A stronger credit profile and a larger down payment typically get better pricing, and you can pay discount points to buy the rate down. One point equals 1% of the loan amount: $3,000 on a $300,000 loan, and it typically lowers your rate by about a quarter of a percent, though the exact trade varies by lender and market. The APR vs interest rate answer explains why the quoted rate and the total cost of credit are two different numbers.
Fixed vs Adjustable: Matching the Loan to Your Timeline
A 30-year fixed rate locks your rate and payment for the full term. The trade-off is that you pay for that certainty with a higher starting rate than an adjustable-rate mortgage (ARM). An ARM holds a low rate for an initial period, commonly 5, 7, or 10 years, then adjusts annually based on an index plus a margin. A typical 5/1 ARM has a 5-year fixed period, then adjusts each year, often capped at 2 points per adjustment and 5 points over the life of the loan.
The rule I give buyers: if you will likely stay 7 years or longer, the fixed rate's certainty is usually worth it. If your plans are closer to 3 to 5 years, an ARM's lower starting rate can save thousands, because you will sell or refinance before the adjustment really matters. My fixed vs adjustable deep dive works through a full $300,000 example with both scenarios.
Conventional vs FHA: The Two Workhorses
Most Texas buyers end up choosing between conventional and FHA financing. Here is what each really requires:
| Feature | Conventional | FHA |
|---|---|---|
| Typical credit minimum | 620 | 580 with 3.5% down; 500 to 579 with 10% down |
| Minimum down payment | 3% with qualifying programs | 3.5% |
| Mortgage insurance | Private MI (PMI) until you reach 20% equity; a fraction of a percent to about 1.5% of the loan per year | 1.75% upfront plus about 0.55% per year, for the life of the loan when you put down less than 10% |
| Debt-to-income ceiling | ~43% to 45% for most buyers | Up to ~57% in qualifying cases |
Let me put numbers on the insurance difference. A $300,000 home with 3.5% down (FHA) has a loan of $289,500. At an example rate of 6%, principal and interest run about $1,735 a month, plus roughly $130 to $140 in mortgage insurance that stays for the life of the loan. On conventional with 20% down, the loan is $240,000; at 6%, principal and interest run about $1,439, and with 20% down there is no PMI at all. The same example at 6.5% costs about $1,516 in principal and interest, roughly $77 more per month than at 6%, which works out to about $27,700 over 30 years. Fractions of a percent matter, but so does the structure underneath them.
Conventional loans above what Fannie Mae and Freddie Mac will buy are jumbo loans. In most Texas counties, the 2026 conforming limit is $832,750 for a single-family home; above that, expect stricter reserve and credit requirements and different rates. The conforming loan answer covers the difference.
What Lenders Actually Check: DTI and Credit Scores
Every mortgage comes down to two numbers: your debt-to-income ratio (DTI) and your credit score. DTI compares your total monthly debts, including the new house payment, insurance, taxes, and HOA if any, to your gross monthly income. Lenders use a housing ratio (about 28% to 31% is the common comfort zone) and a back-end ratio (total debts, typically capped around 43% to 45% on conventional and higher on FHA). The DTI answer works through the calculation line by line, and how much house you can afford applies it to real incomes.
Credit scores set your pricing tiers. At 620 you can qualify for many programs; at 700 the pricing gets better; at 740 or above you are typically in the best rate tier. Lenders use your middle of the three bureau scores, and score improvements of even 20 or 30 points can move your rate, so checking your scores months before you apply is one of the highest-value moves you can make. My credit score hacks article shows the strategies that actually move the number.
Rate Locks: When to Lock and How Long a Lock You Need
A rate lock guarantees your rate for a set period, usually 30, 45, or 60 days, while your loan is processed. Common guidance: lock once you have an accepted offer and a closing date, because the typical purchase closes 30 to 45 days from contract. Locking earlier, before you have a contract, risks paying for time you do not need, and locks carry, or quietly build in, extension costs if the closing slips.
Patrick's advice: Ask your loan officer three questions before locking: how long is the lock, what does an extension cost, and is there a float-down option if rates improve before closing? Then protect the lock by not changing jobs, not opening new credit, not financing large purchases, and keeping your bank statements clean until the day you close. The job change during a mortgage answer explains why lenders re-verify employment so close to closing.
One More Lever: Buydowns and Seller Concessions
In a market where sellers want to move, concessions are gold. Sellers can contribute toward your closing costs or fund a temporary rate buydown, like a 2-1 or 3-2-1 structure, that lowers the payment for the first years without changing the loan amount. On FHA, seller concessions can cover a meaningful share of your costs, and buyers who combine concessions with down payment assistance regularly get to closing with a fraction of the cash they expected. My buydown explainer shows the math behind the 3.99% offers buyers keep asking about.
The honest bottom line: the best loan is the one that fits your timeline, your cash, and your goals, not the one with the flashiest headline rate. That is the conversation I have with every client, and it is why the spread between my real estate license and my lending license keeps deals moving in one direction: toward closing.
Frequently Asked Questions
What credit score do I need to qualify for a mortgage? Tap to expand
How long should I lock my mortgage rate? Tap to expand
Is an adjustable-rate mortgage a bad idea? Tap to expand
What is the conforming loan limit in Texas for 2026? Tap to expand
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Patrick Kevin Fagan
Loan Officer and Realtor | AXEN Realty LLC | San Antonio and Texas Hill Country
Licensed Sales Agent | 454749 | TX | NMLS 877741
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Watch the Video on YouTubeSincerely, Patrick Kevin Fagan