How Long Should You Lock Your Mortgage Rate?

When you apply for a mortgage, one of the biggest decisions you’ll make is whether to lock your interest rate—and for how long. A rate lock is a lender’s promise to hold a specific interest rate for you while your loan is being processed. But not all locks are the same. The length of your lock can mean the difference between getting the rate you expected and paying hundreds of dollars more each month. So how do you choose the right lock period? It comes down to understanding your timeline, the market, and a few practical tips.

First, know what a rate lock actually covers. When you lock your rate, you secure that number for a set number of days—typically 30, 45, or 60 days, though some lenders offer longer periods up to 90 or 120 days. During that time, even if market rates go up, your rate stays the same. If rates drop, however, you’re stuck with the higher one unless you have a “float-down” option, which usually costs extra. The key is to pick a lock period that matches how long it will take to close your loan. If you lock too short, your lock could expire before closing, forcing you to either pay a fee to extend it or accept the current higher rate. If you lock too long, you’ll likely pay a higher upfront cost or a slightly worse rate because lenders charge more for longer locks to protect themselves from market swings.

So what’s the typical timeline? For a straightforward purchase with a good credit score and a clean application, the process often takes 30 to 45 days from application to closing. That means a 30‑day lock might be enough if everything goes smoothly. But life rarely goes smoothly. Your appraisal could be delayed, the seller might need more time, or the underwriter could ask for extra documents. A 45‑day lock gives you a bit of breathing room. If you’re buying a new construction home that won’t be ready for three months, a 60‑or even 90‑day lock might be necessary. Refinances can also vary: some close in three weeks, others take two months if your lender is busy.

Another factor is the current direction of interest rates. If rates are rising, you’ll want to lock as soon as possible, even if it means paying a little more for a longer lock. Waiting even a few days could cost you. If rates are falling or stable, you might be better off with a shorter lock because you can capture a lower rate later—but that’s a gamble. Most experts advise against floating your rate (not locking) unless you have a very solid reason and are prepared to accept a higher rate if the market moves against you.

Lenders also offer “lock and shop” programs that let you lock a rate before you’ve even found a house. This is common for new construction or when you need budget certainty. The trade‑off is that these locks tend to be more expensive and have stricter conditions if closing gets delayed.

Here’s a straightforward rule: never lock for a period shorter than what your loan officer estimates as the minimum closing time. Always add at least a week of padding. If you’re nervous about delays, go for the next longer lock period. And ask your lender what the cost difference is between a 30‑day and a 45‑day lock. Sometimes it’s just a small fee or a slightly higher rate—like 0.125% more. That small cost can save you big headaches if your closing gets pushed back.

One more thing: if your lock does expire before closing, don’t panic. Most lenders will offer a “rate lock extension” for a fee. The fee depends on how long the extension is and current market rates. Sometimes it’s a flat fee, sometimes it’s a percentage of your loan amount. If rates have dropped since you locked, the extension might be cheaper because the lender can re‑lock you at a lower rate. If rates have risen, the extension will be expensive—or the lender may require you to take the current higher rate.

Finally, remember that a rate lock only locks the interest rate, not your monthly payment. Your payment can still change if your loan amount changes (for example, if you put down less than planned) or if you choose a different loan program. Always get a written lock agreement that spells out the rate, the lock period, and what happens if the lock expires. Read it carefully—it’s one of the few pieces of paper in the mortgage process that you can actually understand without a lawyer.

Choosing the right lock length is about balancing cost, risk, and your personal timeline. If you’re buying a resale home, start with a 45‑day lock. If you’re refinancing and your paperwork is ready, a 30‑day lock might work. For new construction or complicated transactions, go with 60 or even 90 days. And always talk to your loan officer. They see closing delays every day and can give you a realistic estimate based on your specific situation. The goal is simple: lock in the rate you want, close on time, and sleep well at night knowing your mortgage payment won’t suddenly jump.