How to Check the Size of a Parcel

To check a parcel's size, compare at least two sources: the acreage recorded by the county assessor and the area calculated from the mapped outline. Then compare both with the listing or the deed. Small differences are normal. A gap you can't explain is a reason to dig deeper before you rely on any one number.

This guide is about verifying a size someone gave you. To measure a shape yourself, see How to Measure Property Area and Perimeter.

Where Parcel Size Numbers Come From

County offices use three words that sound alike. Deeded acreage is what the deed says. Assessed acreage is what the county taxes. Calculated acreage is what software measures from the digital outline. West Virginia's tax-map office, for one, calls the calculated figure “a general estimate only” and says that in its tax-map rules the deeded acreage takes precedence. Rules differ by state, but the pattern is common: the deed outranks the map.

Step by Step

1. Find the parcel on a map and read the acreage shown. See How to Read a Parcel Map.
2. Look up the APN in the county assessor's record and read the acreage or lot size there. Note whether it's in acres or square feet.
3. Find the figure in the deed or legal description, if you have it.
4. Write each number down with its source and unit, then convert to the same unit. If one is in square feet and another in acres, divide by 43,560. See How Big Is an Acre?
5. Check the shape. Does the outline fit what you've been told, including the frontage and any odd extensions?
6. Decide if the difference matters. It matters more for a purchase priced per acre, or if a minimum size is required for building.

Reading the Gap

There's no official tolerance for how much two sources may differ. What counts is whether you can explain the gap. This table covers the patterns that come up most:

Why the Numbers Differ

• Rounding. A 4.6-acre parcel is often called “about 5 acres.”
• Different definitions. Some figures include a road easement or right-of-way, and some don't. Sacramento County's assessor, for example, explains that it assesses usable acreage only, so a parcel whose owner holds title to the middle of a public road is assessed without the road. Some figures include water or a shoreline.
• Old measurements. A deed from 80 years ago may carry a size no one has remeasured.
• Calculated vs. recorded. A map's outline may produce a slightly different area than the recorded figure.
• Several parcels. A listing may include more than one parcel, or part of a larger one.
• Mapping error. Parcel lines are approximate and so is the area they produce. The same Sacramento page notes that assessor maps show information as recorded and aren't surveys.

Lot Size Isn't the Same as Usable Land

Even a correct figure doesn't tell you how much you can build on. Zoning typically sets minimum distances (setbacks) from the front, side and rear lines. Recorded easements, such as a utility strip along a lot line, usually bar permanent structures. Many zoning codes also cap how much of a lot can be covered by buildings, driveways and patios. These rules vary by district and by lot, so check with the local planning or zoning office. A 1-acre lot with a wide drainage easement through the middle can build like a much smaller one.

When to Order a Survey

• The price is based on exact acreage.
• You need to meet a minimum lot size, for example to split the land or get a building permit.
• The sources disagree by a large amount and you can't explain why.
• The boundary is unclear or there are signs of encroachment.

See Property Line Map vs Land Survey for what a survey gives you that a map can't.

What if You Can't Find the Acreage?

• No acreage on the assessor's record. Some counties show only lot dimensions or a square-foot figure. Convert it.
• The map shows no number. Try the county assessor's website, or calculate it (How to Calculate Acreage of a Property).
• The deed says “more or less” only. That's common, and the record doesn't give you a better figure. Use the other sources, or a survey.
• You have a metes-and-bounds description. A surveyor, attorney or lender can run it through a deed-plotting program. West Virginia's tax-map office says these programs draw the shape, estimate the acreage and report whether the description closes back on its starting point.

What if the Recorded Size Looks Wrong?

Gather the deed, the plat and any past survey, and compare their numbers with the assessor's. If the assessor's figure is the odd one out, contact the assessor's office with copies of the recorded documents. A certified survey is the strongest evidence you can bring. Ask what the office's correction process is, since it varies by county.

Frequently Asked Questions

Where can I find my lot size for free?

Search your county assessor's or property appraiser's website by address or parcel number and look for fields such as lot size, land area or acreage. County GIS viewers and parcel maps usually show it too.

Is the assessor's acreage the legal acreage?

Not necessarily. Assessors tax property, and their maps are made for assessment. The deed and any survey are the legal records of the land.

Why does the map show a different acreage than my deed?

The map calculates area from an approximate outline, while the deed states a figure from when the land was described, often with “more or less.” Small gaps are normal.

Does lot size include the road in front?

It depends on the record. Some figures include road right-of-way or easements and some don't, so check how your county defines it.

Common Mistakes

• Comparing square feet with acres without converting.
• Relying on a listing's rounded number.
• Assuming the assessor's acreage is exact. It's an administrative figure.
• Not looking at the shape. Two 5-acre parcels can be very different.
• Treating total lot size as buildable area.

Sources

• About Assessor Parcel Maps (Sacramento County Assessor) Assessed vs. deeded acreage; assessor maps are not surveys.
• Deeded vs. Calculated Acreage (West Virginia Parcel Mapping) Definitions, deed precedence in West Virginia tax maps, deed plotters.
• How to Find Property Lot Size (LegalClarity) Secondary source: assessor lookup, setbacks, easements, lot coverage, correcting records.
• U.S. Survey Foot: Revised Unit Conversion Factors (NIST) Acre = 43,560 sq ft.