Where can I look up my California property lines for free?

Every California county has an assessor parcel viewer that shows approximate property boundaries on aerial imagery. These are free and a good starting point. The California Spatial Information Library also provides statewide parcel data. These tools give you a general picture but are not survey-accurate for placing structures or resolving disputes.

What is the California Spatial Information Library?

The California Spatial Information Library (Cal-Atlas, now part of the California Natural Resources Agency GIS resources) provides statewide GIS datasets including parcel boundaries, aerial imagery, and other geographic data. It is used primarily by planners and researchers. Most homeowners will find their county assessor's online viewer more user-friendly for basic property line research.

How do I find my property's recorded plat in California?

Recorded subdivision maps (plats) are filed with the county recorder. Most California counties provide online access to recorded documents through the county recorder's website or a county records portal. Your property's legal description, shown on your deed and the assessor record, references the subdivision map book and page number where the original plat is filed.

What is a Record of Survey in California?

A Record of Survey (ROS) is a document filed by a licensed California PLS with the county when a survey finds that a boundary differs from what existing maps show, or when monuments are set for the first time. Finding a Record of Survey on file for your property or an adjacent property can provide valuable boundary information. ROS documents are public record at the county surveyor's office.

When do I need a licensed California PLS to find my property lines?

You need a licensed California PLS when placing a fence or structure near the boundary, resolving a boundary dispute, applying for a permit requiring a survey, buying or selling property with boundary questions, obtaining a mortgage on rural or unusual property, or when you cannot locate existing corner monuments. Online tools provide orientation, not legal certification.

How to Find Property Lines in California

Key takeaway

Find your California property lines using county assessor parcel viewers, county recorder plat maps, and the California Spatial Information Library.

What You Are Really Looking For

When California property owners want to find their property lines, the goal is usually one of three things: a rough sense of where the boundary is, the physical corner markers in the yard, or a legally certified boundary for a permit, fence, or dispute. Each goal requires a different approach, and only the last one requires a licensed Professional Land Surveyor (PLS).

Step 1: Use Your County Assessor's Parcel Viewer

Every California county has an assessor's office that maintains property records for tax purposes. Most county assessors provide an online parcel viewer that shows your property's approximate boundaries on aerial imagery. These tools are free and require no account to use.

How to access your county's parcel viewer:

Search for "[your county] assessor parcel viewer" or "[your county] assessor GIS map" in any browser.
Enter your property address or APN (Assessor Parcel Number) to locate your parcel.
The map will show the approximate boundaries of your lot relative to adjacent parcels and aerial imagery.

Examples of California county assessor parcel viewers:

Los Angeles County: assessor.lacounty.gov
San Diego County: sandiegocounty.gov/content/sdc/arcc.html
Santa Clara County: assessor.sccgov.org
Alameda County: acgov.org/assessor
Sacramento County: assessor.saccounty.gov

These maps are approximate. They are based on digitized subdivision maps and aerial imagery, both of which carry measurement error. Do not use them to place a fence, file a permit, or argue a property dispute. Use them to get oriented.

Step 2: Pull the Recorded Subdivision Map or Parcel Map

If your home is in a subdivision, there is a recorded subdivision map filed with the county recorder showing the original lot layout, dimensions, and easements. For rural properties not in a subdivision, you may have a parcel map or a deed with a metes and bounds description.

How to find your subdivision map or parcel map:

Your property's legal description, shown on your deed or the assessor record, references a book and page number in the recorded maps. Example: "Lot 4, Tract No. 12345, MB 234/56" means Subdivision Map Book 234, Page 56.
Search your county recorder's website for recorded documents. California counties have varying online access. Many use a portal where you can search by book and page number.
Some counties provide online access to scanned subdivision maps. Others require a visit to the county recorder's office or surveyor's office.

The subdivision map gives you the original legal dimensions of your lot and shows recorded easements. It tells you what the boundaries are supposed to be. It does not tell you exactly where those boundaries sit on the ground today.

Step 3: Search for a Record of Survey at the County Surveyor

California requires licensed PLSs to file a Record of Survey (ROS) with the county when they set new monuments or when a survey finds a boundary different from what existing maps show. Records of Survey are public documents held by the county surveyor's office.

Why this matters for property line research:

If a prior owner had a survey done and a Record of Survey was filed, it may include boundary information and monument locations relevant to your property.
Records of Survey for adjacent properties can also provide useful reference points.
Some California counties have online searchable ROS indexes. Others require an in-person visit or a request to the county surveyor's office.

Finding and reviewing applicable Records of Survey is one of the first steps a licensed California PLS takes when researching a property for a new survey.

Step 4: Use the California Spatial Information Library

The California Natural Resources Agency maintains statewide GIS data resources through California's open data portal and affiliated resources. Statewide parcel data and other geographic datasets are available for download or online viewing.

For most homeowners, these statewide datasets are harder to use than the county assessor's viewer. They are most useful for rural areas where county tools are less detailed, or for comparing data across county boundaries. Research professionals and licensed surveyors use these resources regularly.

Access statewide California GIS data at gis.data.ca.gov.

Step 5: Look for Physical Corner Markers on Your Property

California property corners are marked by survey monuments set by licensed PLSs. These are typically iron pins, iron pipes, or other durable markers set in the ground at each corner of the lot. In urban areas they may be flush with or just below the surface of the ground, sidewalk, or pavement.

How to look for them:

Start at the obvious corners where your lot changes direction, including back corners and the points where your lot line meets the street or alley right-of-way.
Look for orange or pink survey flagging tape near the ground, which sometimes marks recently located monuments.
Iron pins and pipes can be located with an inexpensive metal detector. Some homeowners find all their corner markers this way.
In areas with concrete or paving, look for a cross or brass disc set in the concrete near the corner location.

Important: you can search for markers but you cannot legally establish, move, or certify them yourself. Only a licensed California PLS can certify the location of a property corner. If you find a marker that appears to have been moved or disturbed, do not touch it.

Step 6: Review Your Closing Documents for a Prior Survey

If you purchased your home with a mortgage or used a title company, there may be a survey or related documents in your closing file. California residential closings do not always include a survey, but when one was done it should be in the file from the escrow company or title company that handled the transaction.

Prior surveys are useful for understanding the lot dimensions and finding any prior monuments. Check whether the survey is still relevant: if improvements have been made, structures added, or corner markers disturbed, the prior survey may need to be verified or updated by a licensed PLS before you rely on it.

When to Hire a Licensed California PLS

Online tools, subdivision maps, and corner markers give you valuable context. But there are situations where only a licensed California PLS gives you an answer you can legally rely on:

You are placing a fence, shed, wall, or addition near the property line.
You have a boundary dispute with a neighbor.
You are applying for a permit that requires a certified survey or site plan.
You are buying or selling property where boundary questions need to be resolved.
You cannot locate corner markers or they appear to have been moved.
Your legal description is in metes and bounds without a recorded subdivision map.

California PLSs are licensed by the California Board for Professional Engineers, Land Surveyors, and Geologists (BPELSG). Verify any surveyor's license at bpelsg.ca.gov.

Typical Survey Costs in California

Standard residential boundary survey on an urban or suburban lot: $600 to $1,500
Larger suburban lot, 0.5 to 2 acres: $1,000 to $2,500
Rural parcel, 2 to 20 acres: $1,500 to $4,000
Properties with complex boundary histories or disputed corners: $2,500 or more

Get quotes from at least two licensed California PLSs. Provide your APN and the legal description from your deed to help the surveyor research the property and give you an accurate estimate.

Find licensed California surveyors near you in the directory. Search by county, compare listings, and contact multiple firms to find the right fit for your property.