Rate Lock vs Float: When to Lock Your Mortgage Rate

How a Rate Lock Works

A rate lock is a lender’s guarantee that your mortgage interest rate won’t change for a specified period — typically 30, 45, or 60 days. When you lock at 6.75% on a Tuesday, that rate stays at 6.75% even if rates jump to 7.25% by the time you close four weeks later. The lock protects you from market volatility during the period between application and closing. On a $350,000 loan, the difference between 6.75% and 7.25% is about $119/month — $42,840 over 30 years.

Locks come in different durations at different prices. A 30-day lock is usually free or included in the base rate. A 45-day lock might add 0.125% to the rate. A 60-day lock might add 0.25%. Longer locks cost more because the lender assumes more risk — they’re guaranteeing your rate for a longer period during which rates could rise. If you’re buying new construction with a 90-day close, a longer (and more expensive) lock might be unavoidable. Check current rates and lock durations before committing.

Rate locks can sometimes be “floated down” if rates drop significantly after you lock. Some lenders offer a one-time float-down option (often for a fee of 0.125-0.25%) that lets you renegotiate to a lower rate if the market moves favorably before closing. Not all lenders offer this, and the terms vary widely. Ask about float-down provisions before locking — they’re free insurance against locking too early in a declining-rate market.

How Floating Your Rate Works

Floating means you haven’t locked — your rate moves with the market every day until you decide to lock or until closing. If you start your application when 30-year rates are 6.75% and rates drop to 6.50% over the next three weeks, you lock at 6.50% and save $57/month on a $350,000 loan. If rates rise to 7.00% instead, you’re now paying $57/month more than you would have if you’d locked on day one.

Floating is essentially a bet that rates will drop (or at least not rise) before you need to lock. It’s an active decision that requires monitoring the market and being ready to lock quickly when rates move in your favor. Most lenders will let you lock same-day when you call. Some offer rate alerts that notify you when rates hit a target you’ve set. The risk: rates can move 0.25-0.50% in a single week during volatile periods. A bad week of floating on a $400,000 loan costs $65-$130/month for 30 years.

There’s a practical constraint: you must lock before closing. Most lenders require the rate to be locked at least 3-7 days before the scheduled closing date. If you float until the last minute and rates spike, you’re stuck with whatever the market offers. Some buyers float right up to the deadline and lock in a panic — rarely the best strategy. Having a target rate in mind and locking when you hit it (or when the lock deadline approaches, whichever comes first) is more disciplined.

Key Differences Between Locking and Floating

Risk allocation is the core difference. A rate lock transfers market risk to the lender — they guarantee your rate regardless of what happens in the bond market. Floating keeps market risk with you. If you’re risk-averse and already happy with the current rate, locking eliminates an unpredictable variable from a process that already has plenty of stress. If you believe rates are trending down and are comfortable with the possibility of being wrong, floating offers potential savings.

Cost certainty affects your entire purchase math. When you lock at 6.75%, you know your monthly payment on a $350,000 loan is $2,270. You can calculate your DTI ratio precisely, set your budget, and negotiate confidently. When you’re floating, your payment could be $2,270 or $2,389 (at 7.25%) or $2,152 (at 6.25%) — a $237/month range. That uncertainty can affect everything from how much house you offer on to whether you qualify at all if rates rise enough to push your DTI over the limit.

Timing pressure differs significantly. A locked rate has an expiration date. If your closing gets delayed beyond the lock period, you may need to pay for a lock extension (0.125-0.375% of the loan amount) or re-lock at current market rates. Floating has no expiration — but it has its own pressure in the form of daily rate volatility. Long closing timelines (45-60+ days) make locking expensive because longer locks carry higher premiums, which can push borderline floaters into the floating camp.

The decision often depends on rate direction. In a rising-rate environment — when the Fed is hiking or inflation is running hot — locking protects you from further increases. In a falling-rate environment — when the Fed is cutting or the economy is slowing — floating can capture lower rates as they come. In early 2026, with the Fed signaling gradual rate adjustments, the direction isn’t entirely clear, which makes the lock-vs-float decision genuinely difficult. Use our mortgage calculator to see how different rates change your payment.

When to Lock Your Rate

Lock when you’re happy with the current rate and can’t afford for it to go higher. If 6.75% works for your budget and 7.25% would strain it, the $119/month risk of floating isn’t worth the potential savings. Lock when rates have been trending up — momentum tends to continue in the short term. Lock when you’re within 30-45 days of closing, when free or low-cost lock durations align with your timeline.

Lock early if you’re buying in a market where closing delays are common. If your contract says 45-day close but your market averages 50-55 days, a 30-day lock will expire before closing, costing you extension fees. Pay for a 60-day lock upfront and have buffer room. The extra 0.125% in rate is cheaper than the 0.25-0.375% extension fee you’d pay if the 30-day lock expires.

When to Float Your Rate

Float when rates are clearly trending downward and you have time before closing. If the Fed just announced rate cuts and mortgage rates have been dropping 0.10-0.15% per week, floating for 2-3 weeks can save meaningful money. On a $400,000 loan, capturing a 0.25% rate drop saves $65/month — $23,400 over 30 years. Float also makes sense if current rates are significantly above recent lows and economic data suggests a correction is coming.

Float when your closing timeline is long (60+ days) and locking for that duration would be expensive. A 60-day lock at +0.25% on a $400,000 loan costs an extra $65/month. If you expect rates to stay stable or decline, floating for the first 30 days and locking with 30 days left (free or cheap lock) saves you the lock premium. The risk is manageable if you have a rate ceiling in mind — “I’ll lock immediately if rates hit 7.00%.”

Common Mistakes to Avoid

Floating because you think you can time the market perfectly. Nobody consistently predicts rate movements. Even mortgage industry professionals get it wrong regularly. Floating for a 0.125% potential savings while risking a 0.50% spike is asymmetric risk. Unless rates are clearly trending down based on concrete economic data (not opinions on Reddit), locking removes a variable you can’t control.

Locking too early with a distant closing date. If your closing is 75 days away and you lock for 30 days, you’ll need to pay for a 45-day extension — often 0.25-0.375% of the loan amount ($1,000-$1,500 on $400,000). Either float until you’re within a manageable lock window or pay for a longer lock upfront. Extensions are almost always more expensive per day than a longer initial lock.

Not asking about float-down options before locking. Some lenders include a free float-down provision; others charge 0.125-0.25% for it. This option lets you capture rate drops after locking — the best of both worlds. If rates drop 0.375% after you lock, the float-down lets you renegotiate. Without it, you’re stuck at your locked rate even if rates plummet. Ask about this feature before choosing a lender, not after.

Panicking and locking during a rate spike. Rates are volatile — a 0.25% jump on Tuesday might reverse by Friday. If rates spike and you panic-lock, you might be locking at a local peak. Unless the spike is driven by fundamental changes (inflation data, Fed policy shift), give it 2-3 business days to settle. Mortgage rates often mean-revert in the short term. But if the spike is policy-driven, locking quickly makes sense because more increases may follow.

Frequently Asked Questions

What happens if my rate lock expires before closing?

You’ll need to either extend the lock or re-lock at current rates. Lock extensions typically cost 0.125-0.375% of the loan amount per 15-day extension. If rates have risen since your original lock, the extension cost plus the original lock rate is still better than current rates. If rates have dropped, you might prefer to re-lock at the lower rate — but check whether your lender allows this or requires you to extend at the original rate.

Can I break my rate lock?

Technically, you can walk away from a rate lock, but you’ll lose any deposit or lock fee you paid, and the lender may refuse to work with you again. Some lenders charge a lock-breakage fee. In practice, if rates drop significantly after you lock, the better option is a float-down provision (if available) or simply accepting the locked rate. Switching lenders to get a lower rate restarts the entire underwriting process and could delay your closing by 3-4 weeks.

How much does a rate lock cost?

A 30-day lock is typically free (included in the quoted rate). A 45-day lock adds about 0.125% to the rate. A 60-day lock adds 0.25%. A 90-day lock adds 0.375-0.50%. On a $350,000 loan, each 0.125% increase adds roughly $36/month to your payment. Some lenders quote lock costs as upfront points instead of rate adjustments — compare both formats to understand the true cost.

Should I lock if rates just dropped a lot?

If rates have dropped substantially and you’re happy with the new level, locking captures that gain. Trying to ride a downtrend to the absolute bottom is market timing — it works until it doesn’t. A 0.50% rate drop already saves $115/month on a $350,000 loan. Locking in that savings is rational even if rates might drop another 0.125%. The risk of rates bouncing back up typically outweighs the potential for an additional small decline.

Do rate locks work for refinances too?

Yes, refinance rate locks work identically to purchase locks. You lock a rate, the lender guarantees it for the lock period, and you close before it expires. Refinances sometimes have longer processing times (30-45 days versus 25-35 for purchases), so consider a 45 or 60-day lock to match the timeline. The stakes are slightly lower with refinances since there’s no purchase deadline — if your lock expires and rates are unfavorable, you can simply wait and reapply later. Use our refinance calculator to evaluate whether refinancing makes sense at current rates.

What moves mortgage rates day to day?

Mortgage rates track the 10-year Treasury yield, which moves based on inflation data, employment reports, GDP growth, Fed policy statements, and global events. The monthly CPI (inflation) and jobs reports cause the biggest single-day rate swings. Fed meeting days also drive volatility. Rates can move 0.10-0.25% in a single day after a major economic release. If you’re floating, pay attention to the economic calendar and consider locking before major data releases.