Quick answer: On a $750,000 Westminster 80031 home with 20% down at 7.18%, the $600,000 loan costs about $4,065 a month. A rate lock holds that rate for 30, 45 or 60 days. If the rate rises 0.25% while you float, the payment jumps about $102 a month.
By Katerina Veteskova, Colorado real estate broker license FA.100082955, eXp Realty, LLC
Buyers in Westminster often ask me when to lock the mortgage rate after they are under contract. The answer depends on your closing date and how much payment risk you can take, so this guide runs the numbers on one loan.
The example is a $750,000 purchase in the 80031 zipcode with 20% down, or $150,000, and a $600,000 30-year fixed loan.
What does a rate lock do on a Westminster purchase?
It holds your interest rate until closing if you close on time and your application stays the same.
The CFPB says a lock-in means the rate will not change between the offer and closing when those conditions are met. If the rate is not locked, it can change at any time. Lenders often offer 30-, 45- or 60-day locks, and sometimes longer.
What does the $600,000 loan cost at 7.18%?
About $4,065 a month in principal and interest.
That uses the 30-year fixed average that Freddie Mac reported as of November 5, 2026, down from 7.24% a week earlier. Over 360 payments, total interest is about $863,259. Your full payment will also include taxes and insurance.
The loan sits under the one-unit conforming limits of $862,500 for Adams County and $862,500 for Jefferson County in the FHFA 2026 county loan limit file, so it is not a jumbo loan.
How much does a 0.25% rise cost if you float?
About $102 more a month, or about $36,704 more interest over 30 years.
At 7.43%, the same $600,000 loan costs about $4,167 a month. The $102 gap is my own amortization math, shown for illustration only. A 0.25% move is an example, not a forecast.
Get new Westminster homes from $700K
Email me new Westminster listings from $700,000 as they come on the market, so I can plan the rate lock before I write an offer.
What if the rate rises 0.50% before you lock?
About $205 more a month, or about $73,756 more interest over the life of the loan.
At 7.68%, principal and interest runs about $4,269. That is why many buyers lock once the purchase contract and loan application are firm enough for the lender to issue a lock agreement.
How long should the rate lock last?
Long enough to cover your expected closing date, with a cushion for delays.
The CFPB notes that extending a lock can be expensive if the transaction needs more time, so match the window to your contract. A 30-day lock can be tight when the appraisal or title work runs long; a 45- or 60-day lock costs more up front at many lenders but reduces extension risk. Ask what each window costs before you choose.
Lock now if:
- Your purchase contract and loan application are far enough along for the lender to issue a lock
- A 0.25% rise would strain the payment you planned
- Your closing date fits inside a 30-, 45- or 60-day window you can buy today
Float a little longer if:
- You are not yet under contract and have no Loan Estimate
- Your lender offers a short float with a clear lock deadline you can meet
- You accept that an unlocked rate can change at any time
Can a locked rate still change?
Yes, if your application changes after the lock.
The CFPB lists common triggers: a different loan amount or down payment, an appraisal that comes in higher or lower than expected, a credit score change, or overtime or bonus pay the lender cannot document. Keep new credit pulls and large purchases off the table until after closing.
Where do I see if my rate is locked?
On page 1 of your Loan Estimate, in the rate-lock field.
Some lenders lock when they issue that form and some do not. The CFPB also says the Loan Estimate must arrive within three business days of your application and shows the estimated interest rate and closing costs. Ask your loan officer, in writing, how long the lock lasts and what an extension would cost.
Is $750,000 a realistic price in 80031?
It is above the recent 80031 median, and it fits the Living Westminster search floors from $700,000.
For the three months ending September 2026, Redfin showed an 80031 median near $490K, about 29 days to sale, and a 98.9% sale-to-list ratio. Browse live Westminster inventory in the Westminster homes from $700K, Westminster 80031 homes from $700K and Westminster $700K to $1M searches, plus Westminster homes from $1.2M for higher list prices.
Where else can a $750,000 budget go near Westminster?
Next door, compare Broomfield homes from $700K, Broomfield 80020 homes from $700K, Broomfield $700K to $1M and Broomfield homes from $1.2M.
West toward the foothills, open Arvada homes from $700K, Arvada 80002 homes from $700K and Arvada $700K to $1M. Southwest, scan Wheat Ridge homes from $700K, Wheat Ridge 80033 homes from $700K and Wheat Ridge $700K to $1M, then Lakewood homes from $700K a bit farther south. The Front Range $700K to $1M board is the metro-wide $700K to $1M cut. Move-up plans are in trading up from $700K to $1.2M+; a first purchase on the Jefferson County side can start with first home in Jefferson County.
Broker view: "When buyers ask me about locking, I want the lock window to cover the closing date with room for a slow appraisal. Paying a little more for a longer lock is often cheaper than an emergency extension." - Katerina Veteskova, eXp Realty, LLC
What this guide does not cover: lender-specific lock fees, float-down options, discount points, lender credits, adjustable-rate loans, FHA, VA and jumbo pricing, refinancing, property tax amounts, homeowners insurance and HOA or metro district dues. This is not financial advice, and your lender can confirm the lock terms on your Loan Estimate.
Sources: Freddie Mac PMMS, 7.18% 30-year fixed as of November 5, 2026, down from 7.24% a week earlier. CFPB rate-lock and Loan Estimate pages, checked November 5, 2026. FHFA 2026 one-unit limits for Adams and Jefferson counties. Redfin 80031 market snapshot for the three months ending September 2026. Monthly payment and interest gaps are my amortization on a $600,000 loan, for illustration only.
Planning a Westminster purchase near $750,000? Call or text 720-646-4685, or request a tour.
Frequently asked questions
How long do rate locks usually last?
The CFPB says rate locks are typically available for 30, 45, or 60 days, and sometimes longer. Ask your lender which window is on your Loan Estimate and what an extension would cost.
Does locking protect me if rates fall?
Not usually. The CFPB notes that a rate lock may lock you out of a lower interest rate if rates fall after you get your loan offer, unless your lender offers a float-down and you qualify for it.
Can a locked rate still change?
Yes, if your application changes. The CFPB lists triggers such as a different loan amount or down payment, an appraisal that comes in higher or lower than expected, a credit score change, or overtime or bonus pay the lender cannot document.
Where do I see if my rate is locked?
Look on page 1 of your Loan Estimate for the rate-lock line. The CFPB says some lenders lock the rate when they issue that form and some do not, so the form itself is the place to look.
Katerina Veteskova is a Colorado real estate broker (license FA.100082955) with eXp Realty, LLC. Call or text 720-646-4685, or request a tour.