Buyers watch rates the way surfers watch swell. And almost all of them share the same quiet misunderstanding: that when a rate looks good, they can grab it.
You mostly cannot. A rate lock attaches to a specific loan on a specific property — which means for most buyers, the window opens only once you have a signed purchase contract. Everything before that is window shopping.
What a Lock Actually Is
A rate lock is your lender's written commitment to hold a specific rate and price for a specific number of days — commonly quoted in 15-day steps, with 30 and 45 days the workhorses.
It is not a vague promise. It names the loan program, the rate, the cost of that rate, and an expiration date. If your loan funds inside the window, you get the locked terms regardless of what the market did in between.
When the Window Really Opens
Because the lock needs a property address and a live loan application, the practical sequence is: offer accepted, loan application completed against that address, then lock.
This is why obsessing over daily rate moves while you are still touring homes is wasted stress. The rate that matters is the one available inside your escrow window — a date you cannot know until you are in contract.
Matching the Lock to Your Escrow
The lock length needs to cover the distance from lock date to funding date, with a little margin. Lock too short to save money and you risk paying an extension fee if escrow runs long. Lock longer than you need and you paid for days you never used — longer locks price slightly worse.
This is a genuinely easy conversation to have with a lender, and worth having before you are in contract: "on a thirty-day escrow, when would you lock, and at what length?"
Two Features Worth Asking About by Name
Neither of these is exotic, and knowing the words changes the conversation:
- Float-down: some locks include (or sell) a one-time option to re-lock lower if the market drops meaningfully before closing. Ask what triggers it and what it costs.
- Extension: if escrow slips past your lock, lenders typically extend for a per-day or per-15-day fee. Ask the price before you lock, not after you need it.
Not Buying for a While? This Still Matters
The lock happens late, but the lender choice happens early — and the lender is who executes your lock under time pressure. Comparing two or three lenders on the same day, with the same scenario, tells you more than any advertised rate. Ask each one the escrow-matching question above and listen for who answers in specifics.
When you are ready to run that comparison for a San Diego purchase, we can point you at lenders our buyers have actually closed with. No pressure either way — it is a better conversation to have early than late.