A mortgage rate lock is a lender's guarantee to hold your quoted interest rate for a set period, typically 30, 45 or 60 days, while your loan moves to closing. If rates rise before you close, your locked rate still applies. If the lock expires first, you may have to pay to extend it or accept whatever the current rate is.

What a rate lock is

Mortgage rates can change daily, even hourly, because they track the bond market, moving with yields on the 10-year Treasury rather than directly with the Federal Reserve's policy rate. So the rate a lender quotes today is not guaranteed to be the rate you get at closing weeks later. A lock bridges that gap. According to the Consumer Financial Protection Bureau, a rate lock keeps your interest rate from changing between the loan offer and closing, as long as you close within the agreed time and your application does not change in a way that affects the rate. Change the loan amount, the property, your down payment or your credit profile, and the lock can be reset or voided. A lock usually covers the interest rate and any discount points you agreed to pay, and it is worth getting the terms in writing so there is no dispute later about what was locked and until when.

How long locks last

> "Rate locks are typically available for 30, 45, or 60 days, and sometimes longer," the CFPB says.

Longer locks give you more protection but usually cost more, either as a higher rate or an upfront fee. The reason is that the lender is taking on the risk that rates rise before your loan closes, and the longer that window, the more that risk is worth. The right length is the one that comfortably covers your expected closing date. Lock for too short a window and you risk the lock lapsing before you close; lock for longer than you need and you pay for protection you do not use. On a straightforward purchase that is weeks from closing, a 30- or 45-day lock is common; a refinance or a slow-moving file may call for 60 days or more.

What happens if the lock expires

If your closing is delayed past the lock period, perhaps because of an appraisal hold-up or a slow underwriting process, the lock can expire. At that point you generally either pay an extension fee to keep the original rate or take the rate available on the day. Because extensions can be expensive, the CFPB suggests asking your lender up front what happens if closing is delayed, and whether a longer lock makes sense from the start.

It is also worth being clear about what a lock does not do. It fixes your interest rate, but it does not freeze your closing costs, which can still move as third-party fees such as appraisal, title and recording charges are finalized. And if rates fall sharply after you lock, some lenders will let you renegotiate or relock at a cost rather than hold you to a rate well above the market, so it is reasonable to ask. A lock is protection against rates rising, not a penalty box.

Lock, float, or float down

Locking removes uncertainty, but it also means you do not benefit if rates fall after you lock. The alternative, floating, leaves your rate exposed to the market until closer to closing, which can pay off if rates drop and hurt if they rise. Floating is a bet on the direction of rates, and most buyers who need a predictable monthly payment prefer the certainty of a lock. Some lenders offer a float-down option, a middle path that lets you take a lower rate if the market falls during your lock, usually for a fee paid upfront or built into the rate. Whether that is worth it depends on the cost, on how far rates have to move before the float-down kicks in, and on how much rates are actually moving at the time.

Where rates sit right now

Context matters when you decide how much protection to buy. Freddie Mac's Primary Mortgage Market Survey put the average 30-year fixed-rate mortgage at 7.24 percent and the 15-year fixed at 6.60 percent in the week of October 29, 2026. Those are national averages and your own quote will differ. You can track the going rate on our U.S. 30-year mortgage rate tracker, and for how the Fed's moves feed through to what you pay, see our explainer on the federal funds rate versus the prime rate.

The document that pins down your rate is the Loan Estimate. The CFPB says the lender must provide you a Loan Estimate within three business days of receiving your application, and it shows the estimated interest rate, monthly payment and closing costs. Keep it, because it is the benchmark you use to check that the rate you were quoted, and later locked, is the rate that shows up on the Closing Disclosure you receive before signing. If the numbers drift without explanation, that is the moment to ask your lender why.

What to watch

Match the lock length to your real closing timeline, and build in a little buffer, because appraisals and underwriting often take longer than expected. Before you commit, ask the lender three questions: what an extension costs if closing slips, whether a float-down is available and at what price, and exactly what could void the lock. Rates on a new-construction purchase that may not close for months are a special case, where a longer or extendable lock can be worth the extra cost. This explainer describes how rate locks work; it is not advice about whether to lock, float or take any particular loan.