Rates jumped again in late September 2026. A rate lock is how you stop that from changing your payment while you close. Here is how it works, what it costs, and what can still move your rate.
By the CalcLedger editorial team · Updated September 2026 · 5 min read · Examples use illustrative rates · How we calculate
Mortgage rates have climbed for three weeks in a row. The Mortgage Bankers Association weekly survey released on September 30, 2026 put the average 30-year fixed contract rate at 7.30%, up from 7.12% and 6.97% the two weeks before, and the MBA said applications fell 6% as buyers and refinancers pulled back. Freddie Mac's weekly average, published on Thursdays, was 7.03% on September 24. If you are under contract on a home or about to be, the question is simple: lock now, or wait?
As the CFPB explains, a rate lock "means that your interest rate won't change between the offer and closing, as long as you close within the specified time frame and there are no changes to your application." Rate locks "are typically available for 30, 45, or 60 days, and sometimes longer." Your Loan Estimate shows whether your rate is locked and until when.
Here is a $320,000, 30-year fixed loan, principal and interest only, at the rates from the last three weekly MBA surveys:
| Rate | Monthly payment | Total interest over 30 years |
|---|---|---|
| 6.97% (week of Sept 11) | $2,123 | $444,109 |
| 7.12% (week of Sept 18) | $2,155 | $455,735 |
| 7.30% (week of Sept 25) | $2,194 | $469,778 |
| 7.55% (another quarter point) | $2,248 | $489,443 |
Monthly payment on a $320,000 loan
30-year fixed, principal and interest
A two-week move from 6.97% to 7.30% adds about $71 a month. A lock would have prevented that. Of course, a lock also means you do not benefit if rates fall before closing, which is why some lenders offer a float-down option.
Pick a lock that covers your expected closing date with some room to spare. Appraisals, title work and underwriting can all run late. Longer locks may cost more or come with a slightly higher rate, but an expired lock can be worse: if rates have risen, you may have to take the new, higher rate or pay to extend.
| Question to ask your lender | Why it matters |
|---|---|
| How long is the lock, and what is the exact expiry date? | Your closing must happen before it. |
| What does an extension cost? | The CFPB notes extending a lock "may be expensive." |
| Is there a float-down option, and what does it cost? | Lets you take a lower rate if rates drop. |
| Is the lock in writing? | A verbal promise is hard to enforce. |
A lock protects you from the market, not from changes in your own file. The CFPB lists changes that can alter a locked rate, including:
Nobody can predict next week's rates, and this guide does not try. A simple test: if the payment at today's locked rate fits your budget, locking removes the risk. If you would only buy at a lower rate, the risk runs the other way. You can also lower your locked rate by paying points; the mortgage points calculator shows how long they take to pay back. For more context, read what rates above 7% mean for you.
Using a 28% housing ratio, with property tax at 1.1% of the price and insurance of $1,600 a year, the income needed for a $400,000 home with 20% down rises from about $112,900 at 7.03% to about $115,400 at 7.30%. Check your own number with the home affordability calculator.
When should I lock my mortgage rate?
Many buyers lock once they have a signed purchase contract and a lender, and choose a lock that covers the closing date. If the payment at the current rate works for you, locking removes the risk of a rate increase before closing.
Does a rate lock cost money?
A standard lock is often included in your loan pricing, but longer locks, extensions and float-down options can cost extra. Ask for the costs in writing.
Can my rate change after I lock?
Yes, if your application changes: a new loan type or down payment, a different appraisal, a lower credit score, or income you cannot document.
What happens if my rate lock expires?
You may have to pay to extend it or accept the current market rate, which could be higher. Ask your lender now whether a longer lock is available.
Rates in this guide are national weekly averages from the Mortgage Bankers Association and Freddie Mac; your quote depends on your credit, down payment, loan type and lender.
Rules, limits and program details are checked against these official sources. Example numbers are calculated by CalcLedger with the formulas on our how we calculate page. Read our editorial policy.