What free online tools can tell you about your home's value
Several websites let you enter your address and see an estimated value for your home at no cost. The most widely used are Zillow, Redfin, Realtor.com, and Trulia — each pulls data from public records, recent sales nearby, and property characteristics to generate a number called an automated valuation model, or AVM. These estimates are free to view and require only your address.
The catch is that these numbers are estimates, not appraisals. An appraisal is a formal document prepared by a licensed professional who walks through your home and compares it to similar properties that sold recently in your area. An AVM is a calculation based on data the website has access to, without anyone seeing your house. The difference between the two can be thousands of dollars, especially if your home has unusual features, recent upgrades, or sits in a neighborhood where comparable sales are sparse.
Free online estimates are useful for getting a ballpark sense of what your home might be worth — useful enough to decide whether to list it, refinance, or challenge a property tax assessment. They are not useful for making a final decision about selling or borrowing against your home, because lenders and buyers will not accept them as proof of value.
Key Takeaways
- Zillow, Redfin, Realtor.com, and Trulia all offer free home value estimates by address, though each uses slightly different data and methods.
- These online estimates are automated calculations, not appraisals, and can differ from a professional appraisal by thousands of dollars.
- Free estimates work well for a rough sense of value but not for decisions that require proof, like refinancing or selling.
- Your county assessor's website usually shows your home's assessed value for tax purposes, which is public record and free to view.
- Recent sales prices of similar homes in your neighborhood, visible on most real estate sites, often tell you more than a single estimate number.
Where to find free estimates and what each site shows
Zillow calls its estimate a "Zestimate" and displays it prominently on the property page along with a range showing how confident the algorithm is. You can see the estimate without creating an account. Zillow also shows recent sales in the area, property tax history, and a rough breakdown of what features add or subtract value.
Redfin provides an estimate labeled as such and includes a confidence range. Redfin's data tends to weight recent sales more heavily than older ones, so its estimates can shift more noticeably when a nearby home sells. The site also shows you the actual listing history of your home if it has been on the market before.
Realtor.com (run by the National Association of Realtors) displays an estimate and shows comparable sales side by side with your property. The interface is designed to help you see which homes the algorithm used as comparables and why.
Trulia, now owned by Zillow, offers estimates similar to Zillow's but with a slightly different interface. It is less commonly used than the others but pulls from the same underlying data sources.
How these estimates actually work
Each site's algorithm looks at public records — your home's square footage, lot size, number of bedrooms and bathrooms, year built, and any major renovations on file. It then finds homes that sold recently in your area with similar characteristics and adjusts for differences. If your home has three bedrooms and a comparable sold for $300,000, but that comparable has only two bedrooms, the algorithm adds an estimated value for the extra bedroom.
The problem is that algorithms cannot see things that matter to buyers: the quality of the kitchen renovation, whether the roof is original or new, whether the neighborhood is getting better or worse, or whether your home has a view, a noisy road nearby, or sits next to a commercial property. They also struggle in neighborhoods where few homes have sold recently, or where homes vary widely in condition and price.
Most sites show you a confidence range or margin of error — Zillow might say your home is worth $450,000 with a range of $405,000 to $495,000. That range reflects the algorithm's uncertainty. A narrow range usually means many similar homes have sold recently. A wide range usually means the algorithm is less sure.
Your county assessor's value versus online estimates
Your county assessor maintains a public record of your home's assessed value, used to calculate property taxes. This value is often lower than market value because assessors in many states are required by law to assess at a percentage of market value — sometimes 50%, sometimes 100%, depending on your state. You can find your assessed value by searching your county assessor's website (search "[your county] assessor" online) and entering your address.
The assessed value is not the same as what your home would sell for. It is a number used for tax purposes and is updated on a schedule set by your state — sometimes every year, sometimes every three or five years. It can lag behind actual market changes. However, if your assessed value seems wildly out of line with recent sales of similar homes, you may be able to challenge it and reduce your property taxes.
Why recent comparable sales matter more than a single estimate
Instead of relying on one website's estimate, spend a few minutes looking at homes that actually sold near you in the last three to six months. Most real estate sites let you filter by sale date and show the final sale price. Look for homes similar to yours in size, condition, and location. If three homes like yours sold for $420,000, $435,000, and $428,000 in the last month, you have a much clearer picture than any algorithm can give you.
Pay attention to what "similar" means. A home two blocks away in a different school district, or on a busier road, or in noticeably better condition, is not a true comparable. The best comparables are homes that sold within a few blocks of yours, in the same school district if possible, and within the last 90 days. Older sales are less useful because the market may have shifted.
When a free estimate is enough and when you need a real appraisal
A free online estimate is sufficient if you are curious about your home's value, thinking about whether to list it, or deciding whether to challenge your property tax assessment. It gives you a starting point for a conversation with a real estate agent or tax assessor.
You will need a professional appraisal if you are refinancing your mortgage, taking out a home equity loan, or selling your home. Lenders require an appraisal because they need an independent, documented assessment of value before they will lend money against your home. Buyers' lenders also require appraisals as a condition of the mortgage. An appraisal typically costs $300 to $500 and takes one to two weeks.
If you are selling, a real estate agent will provide a comparative market analysis (CMA) as part of their service — this is similar to an appraisal in that it compares your home to recent sales, but it is not a formal appraisal and is not independent of the agent's interest in listing your home.
How to use multiple estimates to narrow down a range
Check your home on at least two of the major sites — Zillow and Redfin are the most commonly used — and note both estimates and their confidence ranges. If Zillow says $450,000 (range $405,000–$495,000) and Redfin says $465,000 (range $440,000–$490,000), the overlap is roughly $440,000 to $490,000. That overlap is often a more realistic range than either estimate alone.
Then look at the comparable sales each site shows and verify them yourself. Did that home actually sell for the price listed? Is it truly comparable to yours? Removing outliers — a home that sold in foreclosure, or one that is significantly larger or smaller — usually gives you a clearer picture.
Write down the three to five most recent comparable sales and their prices. Average them. That average is often closer to what your home would actually sell for than any single online estimate, because it is based on real transactions rather than an algorithm.
Frequently Asked Questions
Do I have to create an account to see my home's value on Zillow or Redfin?
No. Both sites show estimates and comparable sales without requiring you to sign up. Creating an account lets you save homes and set up alerts, but viewing a value estimate is free and anonymous.
Why do different websites give me different values for the same house?
Each site uses slightly different data sources, weighting methods, and comparable sales. Zillow might emphasize recent sales more heavily, while Redfin might include more historical data. Differences of 5 to 10 percent are normal. Larger gaps usually mean the algorithm is uncertain, which is why looking at actual comparable sales is more reliable.
Can I use a free online estimate to refinance my mortgage?
No. Lenders require a professional appraisal, not an online estimate. An appraisal costs money and takes time, but it is the only value a lender will accept as proof that your home is worth enough to borrow against.
What if my home's online value seems way too high or way too low?
Check the comparable sales the site used. If they included a home that sold in foreclosure, or one that is much larger or smaller than yours, the estimate may be skewed. Look at recent sales of homes truly similar to yours and see if the estimate falls within that range. If it is still far off, the algorithm may not have enough recent sales data for your area.
Is my county assessor's value the same as my home's market value?
Usually not. Assessed value is used for property taxes and is often lower than market value. It is also updated on a schedule (yearly, every three years, or every five years depending on your state) and may lag behind current market conditions. Market value is what your home would sell for today.