How Much Is My Seattle House Really Worth? Online Estimates vs. a Real CMA

How much is my Seattle house really worth? Treat an online estimate as a starting point, then price from a comparative market analysis (CMA): a local agent’s review of recent Seattle-area sales, adjusted for your home’s condition, lot, and features.

Type your address into a website and you get a number in seconds. It feels precise. It is an estimate, and it should not be your list price. An online estimate is a computer’s guess made without ever seeing your home.

Here is how those estimates are built, why two of them can disagree by a lot, what a CMA adds, and how an appraisal and the King County assessed value fit in. At the end, I’ll show you how to use all four without letting any one of them set your price.

What an online estimate actually is

Online value tools are automated valuation models, usually called AVMs. An AVM is software that uses statistical models built from recent sales, public records, and other data to estimate what a home is worth, based on the facts it has on file about your home, such as location, square footage, bedrooms, bathrooms, and lot size. It returns a number.

Federal regulators define the term, for lending purposes, as “any computerized model used by mortgage originators and secondary market issuers to determine the collateral worth of a mortgage secured by a consumer’s principal dwelling.” Banks use these models too, and the agencies behind the rule require lenders to put quality controls around them, including random sample testing and reviews. That requirement is a reminder that these models need checking, even in the hands of lenders.

Online estimates are useful for a few things: they show you a rough range and how it moves over time, and they help you spot wrong facts on file. Where they run into trouble is the step from “rough range” to “the price I should list at.”

What the model can’t see

An AVM works from the data it has. It does not walk through your front door. It does not know whether the kitchen was redone last year or has been original since the house was built, whether the basement has a separate entrance and a permitted unit, whether the street is quiet or sits on a busy arterial, or whether the view is a slice of the Sound or a neighbor’s fence. In Seattle, those details can move value significantly, and none of them reliably shows up in the public record.

Why two estimates of the same house disagree

If you have checked your value on more than one site, you have probably seen different numbers. That is normal. The CFPB makes the same point about the valuations lenders receive: they can differ because they are estimates and may be based on different comps, may have been completed at different times, or may have been completed for different purposes.

In plain terms, each tool is working from its own data:

• Different sales: One model might lean on a sale three blocks away, and another on a sale a mile away.
• Different records: Public records can be wrong or out of date. A finished basement, an added bathroom, or a remodel may not show up, or may show up wrong.
• Different timing: A model that updates on its own schedule may not yet reflect the last few weeks of sales.
• Different method: Each company builds its own formula and does not publish all of it.

When two estimates sit far apart, that gap is a clue, not a coin flip. It usually means your home has features or surroundings that the data handles poorly.

What a CMA is, and what it is not

A comparative market analysis, or CMA, is a valuation prepared by a licensed real estate agent. It is built the way I would build a pricing strategy for a listing: I pull the sales that closed recently near your home, and then I compare your home to each of them.

Washington law treats a CMA as a broker’s price opinion. Under RCW 18.140.010, a “comparative market analysis” means a “brokers price opinion,” which is an oral or written report of property value prepared by a real estate broker or salesperson licensed under chapter 18.85 RCW. A CMA is not an appraisal. The same chapter says a broker price opinion may not be used as an appraisal in conjunction with a federally related transaction, which is why a buyer’s lender usually orders a separate appraisal later.

A good CMA covers more than a list of sold prices:

1. Closed sales near your home. These show what buyers actually paid, not what sellers hoped for.
2. Pending sales. These show where the market is heading right now, before the sale closes.
3. Active listings. These are the homes your buyer will compare yours against today.
4. Expired and withdrawn listings. When they are relevant, homes that sat and did not sell show how soft the market is and where buyers pushed back on price.
5. A walk-through of your home, if you invite me over. This is where condition, layout, light, noise, and the little things that never make it into a database get weighed.
6. Adjustments. I account for differences between your home and each comparable one, such as a larger lot, a newer roof, a finished lower level, or a better location on the block.

A hypothetical example

Hypothetical, for illustration only and not real sales or market data: say an online tool shows $1,000,000 for a Seattle house. A nearby home that closed at $1,050,000 has a fully updated kitchen and baths, and yours still has the original ones. A CMA adjusts that comparable’s price down to account for the difference. A second comparable closed at $960,000 but has no usable lower level, and yours has a finished one with its own entrance. A CMA adjusts that comparable’s price up. Neither adjustment shows up in the online number, because the tool never saw the kitchen or the basement. The dollar amounts of real adjustments depend on the market and the specific homes, and I would set them from the actual sales, not from a rule of thumb. The point is the method: each comparable gets adjusted to match your home, and no single sale sets the price.

Estimate, CMA, appraisal, and assessed value side by side

People mix these four up all the time, and each answers a different question.

	Online estimate (AVM)	CMA	Appraisal	County assessed value
Who produces it	Software	Licensed real estate agent	Licensed appraiser, hired through the lender	King County Assessor
Sees your home in person?	No	Yes, in a proper CMA	Depends on the loan and report type	Not for your sale; set for tax purposes
Main purpose	Quick range	Choosing a list price	Supporting a mortgage loan	Setting the property tax base
Built on	Public records and recent sales	Closed, pending, and active comparables plus your home’s condition	Closed comparables, adjusted (Fannie Mae requires at least three)	Mass valuation of parcels, as of a set date each year
Limits	Cannot see condition, view, or unrecorded upgrades	An opinion, not an appraisal	Usually ordered after you have a buyer under contract	Tax figure, not a sale price

The “at least three closed comparables” figure is the minimum in the Fannie Mae Selling Guide, which says a minimum of three closed comparables must be reported in the sales comparison approach. The same section says sales that have closed within the last 12 months should be used, with exceptions when an older sale is the best indicator of value.

Your King County assessed value is not your list price

Many sellers see the number on their property tax statement and wonder whether that is the home’s value. It is related to value, but it is built for a different purpose.

King County explains that state law requires assessors to value property at 100% of “true and fair” value, which Washington courts have interpreted as fair market value. In other words, the target is market value. But the county sets the number for tax purposes, not to price your listing. It also values most properties as of January 1 of the year before the tax is paid, so the number can lag the market on the day you list.

Use the assessed value as a sanity check on your property’s basic facts: lot size, square footage, and year built. If the county has your home listed with the wrong number of bedrooms or bathrooms, tell your agent, because the same wrong data can feed the online estimates.

How a lender’s appraisal differs from a CMA

If you accept a buyer who is using a mortgage, their lender orders an appraisal. The seller does not pick the appraiser. Fannie Mae’s guide says the lender is responsible for appraiser selection, and lenders may not use appraisals ordered by borrowers or other parties with an interest in the transaction. The guide also requires appraisers to have the knowledge needed for the specific geographic location and property type.

The reason this matters to you as a seller: your price has to hold up against the appraiser’s comparables. If I price your home from the recent sales an appraiser is likely to use, there is a better chance the appraisal supports the contract price. If I price from an online number that overstates the home, you can accept an offer and then watch the appraisal come in low. My article on how to price your home to sell in King County’s shifting market goes deeper on the pricing side.

Your own number depends on your condition, your street, and your timing. You can see how I set a list price in How I Price Homes to Sell in Seattle.

What a wrong price costs you

A price set from the wrong number costs money in either direction.

• Too high: Your home typically gets its most attention in the first days on the market. If the price is out of line, buyers pass, the listing sits, and you end up cutting the price after the best exposure is gone. I wrote about that pattern in how to price your Seattle home so you don’t need a price cut.
• Too low: You can leave real money on the table, and a low list price does not always create the bidding you hope for.

Either way, the price should come from the sales your buyers will compare yours to, not from a number that was calculated without looking at the home.

How to use an online estimate the smart way

Online estimates have a place. Use them for what they do well.

1. Check the facts it has on file. Bedrooms, bathrooms, square footage, lot size, and year built. Wrong inputs mean a wrong output.
2. Look at the range, not the single number. If two tools are far apart, ask why.
3. Watch the direction. A trend over several months tells you more than one reading.
4. Look at the comparable sales it shows. If they are far away, much larger, or much newer, the estimate is probably off.
5. Bring your own list of upgrades. Roof, windows, furnace, kitchen, baths, permits, and anything finished. These are the items a database misses.
6. Ask for a CMA before you pick a number. The estimate is the question. The CMA is the answer.

When the estimate and the CMA disagree, trust the one that can explain itself. If a CMA comes in well below an online number, ask which sales pulled it down and what the agent saw in the home or on the street that the data missed. If it comes in above, ask the same thing. A good answer names specific sales and specific features, such as a lot that backs onto a greenbelt, a roof near the end of its life, or a lower level that buyers will count as living space. A vague answer is a reason to ask for the comparables in writing before you set a price.

To see where an estimate lands first, you can see your home’s estimated value in 30 seconds, a starting point only, then ask me to check it against the real sales.

What to expect from a CMA visit

When I do a CMA for a Seattle homeowner, here is the process, and you can ask any agent for the same.

Before the visit, I review the recent closed, pending, and active sales around your address and note which ones are true comparables and which are not.

During the visit, if you invite me to your home, I walk it with you. I look at condition, layout, natural light, noise, the basement or lower level, and the lot. I ask what you have updated and when, and I ask about anything that was permitted or done without a permit, since both affect value and buyer questions later.

After the visit, you get a range and a recommended list price, with the comparable sales behind it, so you can see why. For a condo or townhome, I can look at the association’s dues, reserves, and any special assessments when you share them with me or when they are publicly available in the MLS record, since buyers weigh those. If you want to know what I’d fix or leave alone before listing, my pre-sale concierge program covers upgrades and repairs, and my article on what it costs to sell a house in Seattle helps you see what you would net.

If an agent hands you a number without seeing your home, ask how they got it. A price you cannot explain is a price a buyer will test.

Frequently Asked Questions

Are online home value estimates accurate for Seattle homes?

They can land close for a standard home in a neighborhood with many similar recent sales. They are less reliable for homes with views, unusual lots, additions, accessory units, or recent remodels, because that information may not be in public records. Use them for a rough range, then confirm with a CMA that reflects the home itself.

What is the difference between a CMA and an appraisal?

A CMA is a pricing opinion from a licensed real estate agent, built to help you choose a list price. An appraisal is an opinion of value from a licensed appraiser, usually ordered by a lender to support a mortgage loan. Washington law says a broker price opinion cannot be used as an appraisal in a federally related transaction.

Is my King County assessed value what my house will sell for?

Not necessarily. The county values properties in bulk for tax purposes, as of a set date, and does not appraise your home for a sale. It aims for market value, but a sale on a given day can come in higher or lower. Treat it as one data point and a way to check your home’s basic facts.

Does a CMA cost anything?

A CMA from me comes with additional helpful information, and you can also request a free seller report if you want one. Tell me which you would like so I send the right one. If you invite me to walk through your home, I can factor in condition and features, which an online tool cannot see. If you are only curious about your value, the estimator is a faster first step.

How often should I check my home’s value?

If you are not planning to sell, checking a few times a year to see the trend is plenty. If you plan to sell within the next year, ask for a CMA when your plans firm up, because the sales that matter are the ones from the weeks before you list.

Get the number to price from

If you are thinking about selling, start with a real look at your home, not an estimate from a screen. I’ll review the recent Seattle-area sales around you, walk your home if you invite me over, and give you a range with the sales behind it. Request your free seller report and consultation on HomeProAssociates.com, or call or text Emily Cressey at 206-245-8813.