How to Read a Parcel Map
By AcreBound Editorial Team Updated:
Quick Answer
Find the property, tap the outline around it, and read the parcel number and acreage. Then check neighboring parcels and compare the map with what’s on the ground.
On county sheets, solid lines are usually boundaries, dashed lines are lot, road or section lines, and circled numbers are parcels. Check your county’s key, since symbols vary.
A parcel map looks like a pattern of lines and numbers, but there's not much to it once you know what to look for. If you haven't used one before, What Is a Parcel Map? explains what the map is made of. This guide covers how to use it: find the parcel, read its outline and number, check the acreage, look at the neighbors, then compare the map with the ground.
Step by Step
1. Find the property
Search the address, or zoom to the place using roads and landmarks. If you're standing on the land, use the map's location button to center on yourself. For land that has no address, see how to find a property that has no street address.
2. Identify the parcel boundary
Look for the closed outline around the property. Maps show it in different ways: a colored line, a shaded area or a highlight when you tap it. Tap or click inside the outline to select it. If a panel opens with details, you have the right parcel.
Check that the shape makes sense. Does the outline include your house? Does it reach the road where you expect it to? If not, you may have selected a neighbor.
3. Find the parcel number
The parcel number (APN or parcel ID) is the key to the parcel's records. It's often shown in the details panel, or printed as a small label on the parcel. Write it down. You can use it to find the parcel again, to search county records and to check you have the right property. See how to find the APN for a property.
Don't try to decode the number unless you know your county's format. Whatcom County, Washington, builds parcel numbers from township, range, section and map coordinates, so the first digits tell you which map sheet to open. Ventura County, California, strings together an assessor's map book, page, block and parcel. Same idea, different recipe.
4. Check the acreage
Compare the acreage shown on the map with what you expect. Your deed or tax bill may state the acreage. A small difference is normal because records round numbers and maps calculate area from the outline. A large difference means something is wrong: you may be looking at the wrong parcel, or the property may consist of more than one parcel.
5. Look at the neighboring parcels
Neighbors give context. Notice how big the surrounding parcels are, where the roads run and whether your parcel has access to a road. If several adjacent parcels have the same owner or similar numbers, that often means a bigger property was split. Parcels that are touching and in a row, with consecutive numbers, were often created together in a subdivision. For a method, see how to research neighboring parcels.
An owner listed as a city, county, state or federal agency means public land. On El Dorado County's assessor maps, for example, “U.S.A.” marks land owned by the federal government, which could be BLM land.
6. Compare the map with the real world
Finally, look at what's really there: buildings, driveways, fences, trees and roads. Compare them with the map. This tells you how closely the map follows the ground. If the map shows your house in the middle of the parcel and that matches reality, the data is probably a good fit in your area. If it looks off, keep that in mind when interpreting lines near something that matters.
Reading County Assessor Sheets and PDFs
Some counties still publish the older kind of map: a page-sized sheet with numbers and symbols instead of a clickable layer. The key is usually printed on the county's site. The table below uses two California counties as examples, Placer and Ventura. Another county may use different symbols for the same thing, so find its own key first.
| What you see | What it usually means |
|---|---|
| Solid line | A property boundary |
| Dashed grey line | An original lot line, road boundary or section line, and sometimes a creek, canal or reference line |
| Number inside a circle | The number assigned to that parcel |
| Number inside an ellipse | The assessor's block number for that part of the page |
| A figure like 13.1 ac. | Acreage. Placer shows it only on parcels of at least one acre |
| N76°39′30″E 245 | A bearing and distance: north 76 degrees, 39 minutes, 30 seconds east, 245 feet |
| A bare number with no circle | Often a lot number from a recorded map |
| A small hook between two shapes | Links pieces of one holding, but counties differ. Ventura uses it for a parcel split by a road or channel, and Placer has several hook styles, including one for a single parcel with several APNs |
| Section, township and range in the heading | The part of the government survey grid the page covers |
Scale matters on these sheets. El Dorado County gives 1 inch = 200 feet as an example of a large-scale map with plenty of detail, and 1 inch = 1,200 feet as a small-scale map that covers more ground and shows less. It also cautions that paper copies may not be as true to scale as the originals, so if you need a dimension, take it from the recorded plat or deed instead of a ruler.
The same county lists the abbreviations you'll run into. A few of them:
| Abbreviation | Meaning |
|---|---|
| PM | Parcel map (a recorded one) |
| RS | Record of survey |
| R/W | Right of way |
| P.U.E. / S.D.E. | Public utility easement / storm drain easement |
| M/R | Mineral rights, which may have their own parcel number |
| U.S.A. | Owned by the federal government |
What a Parcel Boundary Is Not
This is where most misreadings happen.
- A parcel boundary is not a fence. Fences are often placed inside or outside the true line, and some boundaries have no fence at all.
- A parcel boundary is not the edge of the road. Depending on the area, a parcel may extend toward the road's centerline or stop at the edge of a public right of way. Either way, the pavement edge isn't automatically the boundary.
- A parcel boundary is not an object in the satellite image. A tree line, a ditch or a lawn edge may roughly follow the boundary, but the line itself is a record, not a feature on the ground. The photo and the line also come from different sources, and each has its own error. When they agree on screen, that's two approximations lining up.
What If the Parcel Does Not Appear?
It may be missing because the county hasn't published parcel data, the data isn't available in the app you're using, or the parcel is new and hasn't been added yet. Try the county's own parcel viewer. If you can't find the parcel anywhere, call the county assessor's office.
What If the Map and the Ground Disagree?
If the difference is small, it may be the natural error of an approximate map. If it's large, check again that you have the right parcel. If you still see a difference and it matters, check the deed and plat, and consider a survey. How Accurate Are Online Property Lines? explains why this happens.
Frequently Asked Questions
What do the dashed lines on a parcel map mean?
Often old lot lines, road boundaries, section lines or features like creeks, though it depends on the county's key. A solid line is usually the current property boundary.
What do the numbers on a parcel map mean?
A number in a circle is typically the parcel number. Numbers beside a line are bearings and distances, and a figure with “ac.” is acreage. Check the county's key, since symbols vary.
Does a parcel map show easements?
Rarely, and never reliably. An assessor's office may not draw them at all. Look in the deed, the recorded plat and the title report.
Does a parcel map show property lines?
It shows parcel lines drawn from records. They're a good guide to where a property is and a poor guide to exactly where a corner sits.
Common Mistakes
- Selecting the wrong parcel and reading someone else's details.
- Reading the line as if it were exact.
- Forgetting that one property can be several parcels.
- Using the map to decide where to build or dig.
- Applying one county's symbols to another county's map.
To see how maps fit into the larger picture, read How to Find Your Property Lines.
Sources
- How to Read Your Assessor’s Parcel Map (Placer County, CA) Symbols for lines, circles, bearings and acreage.
- Instructions for Identifying Assessor’s Parcel Numbers (Ventura County Assessor, CA) Parcel number structure and map symbols.
- About Assessor’s Maps (El Dorado County Assessor, CA) Abbreviations, scale, easements.
- Reading PDF Maps (Whatcom County, WA) Decoding a township-range-section parcel number.