Lock-and-Shop Mortgage Rate Lock Cost Calculator
Lock-and-shop programs let house-hunting buyers lock a mortgage rate for 60-120 days before they have a contract. Calculate the fee cost, the rate-rise protection benefit, and your break-even — would you have saved money floating instead?
| Loan Amount | — |
| Lock Length | — |
| Gross Lock Fee | — |
| Net Lock Fee (after refund) | — |
| Locked Rate | — |
| Expected Float Rate | — |
| Locked Monthly Payment | — |
| Float Monthly Payment | — |
| Lifetime Savings from Lock (gross) | — |
| Net Value vs Floating | — |
What Lock-and-Shop Means
A lock-and-shop rate lock secures your mortgage interest rate before you have a purchase contract. Traditional rate locks require an accepted offer; lock-and-shop programs let house hunters lock for 60, 90, or 120 days while they're still touring homes. This protects against rate spikes while you negotiate offers.
Most lenders charge a small fee (0.125% to 0.5% of the loan amount) at lock time. Many large lenders — Rocket, Chase, Wells, US Bank — refund the fee or apply it as a credit at closing if you complete the loan with them. Other lenders keep it. Always confirm refundability in writing before locking.
The Real Cost-Benefit Math
Locking has value only if rates actually rise during the lock window. On a $400,000, 30-year loan at 6.85%, a 0.40% rate rise costs you about $107/month and $38,500 over the life of the loan. If the lock fee is refundable, locking is a free option — pure upside.
If the fee is non-refundable, you're paying a premium for peace of mind. Calculate the break-even rate rise above which the lock pays for itself. For a 0.25% fee on $400K ($1,000), the break-even is roughly 0.04% rate rise — meaning if rates move just 4 basis points up, you've made the fee back.
Source: Federal Reserve FRED 30-year fixed mortgage rate history shows 30-day moves of 25-50bp are common in volatile markets
Float-Down Option — The Key Detail
What if rates drop after you lock? Without a float-down, you're stuck at the higher rate or pay to break the lock. The best lock-and-shop programs include a one-time float-down option: if market rates drop more than 0.25% during your lock window, you can re-lock once at the lower rate.
Always ask the lender directly: 'Does my lock include a float-down? At what trigger? Any fee?' Get the answer in writing before paying the lock fee. A lock without float-down is a one-way bet on rising rates only.
When Lock-and-Shop Is and Isn't a Smart Move
Lock-and-shop makes sense when: rates are climbing, your house search is concentrated (under 60 days), and the fee is refundable. It doesn't make sense when: rates are flat or declining, your search is open-ended (6+ months), or the fee is steep and non-refundable.
If you're not ready to lock, our mortgage points calculator and refinance savings calculator help model rate scenarios for both purchase and future refi.