GPIN (Grid Parcel Identification Number)

The Grid Parcel Identification Number (GPIN) is a unique parcel identifier that is based on the location of a parcel's centroid, and is used to index all records associated with a parcel. The use of the GPIN simplifies the identification of parcels on a map.

Activity that affects GPIN

The GPIN is an identifier based on our proprietary grid, the number gives no information about what subdivision a parcel belongs to or what parcel it was created from. This information is derived from related tables describing the subdivision and the parent-parcel. If the configuration of a parcel is changed, such as any boundary adjustment regardless of the measurement, that parcel ceases to exist and a new identifier is assigned to the new parcel(s).


Any parcel separated by a road or disjoined from itself as a result of subdivision, but still considered a single parcel will be assigned a single GPIN. Each polygon associated with the parcel will be assigned an individual centroid; however, the GPINs will be identical. The choice of GPIN is performed using the GIS software and is not related to size or any other characteristics of the polygons.


How is a GPIN Assigned?

The GPIN is based on a combination of Easting (X) and Northing (Y) values at the center of a parcel, based on the Prince William County proprietary grid. It is a unique identifier that references location only, and carries no other parcel attribute information. The GPIN can be thought of as having a telescopic or 'zooming' effect on defining the parcel location in an area, by identifying a 10,000' square, then a 1,000' square, and finally a 10' square, all within the original 10,000' square. This reduces the time required for a user to search a crowded mapsheet for a small parcel.


The 4 digit XXYY coordinate references a 10,000' grid square. This coordinate is defined by a combination of the 100,000’ and 10,000’ place digits of the Easting(x) and Northing(y) values. The millions places are not a part of the GPIN identifier since all the parcels in Prince William County can be identified uniquely without reference to them. 

Example 1.1:

X: 11720450 – 72

Y:   6981170 – 98

This coordinate value would produce 7298 as the initial 4 position portion of a GPIN (7298-XY-XXYY).

The next set of coordinates is XY, referring to the 1,000 place digits in the Easting(x) and Northing(y) values. This coordinate further narrows down the location of the parcel by defining the 1,000' square in which the parcel lies.

Example 1.2:

X: 11720450 – 0

Y:   6981170 – 1

This coordinate value would produce 01 as the initial 2 position portion of a GPIN (7298-01-XXYY),

The next set of 4 digits narrows down the parcel centroid location to a 10' square.  It is composed of the 100’ and 10’ place digits in the Easting(x) and Northing(y) values.

Example 1.3:    

X: 11720450

Y: 6981170

This coordinate value would produce 4517 as the final 4 position portion of a GPIN (7298-01-4517). 

The last set of two digits (ZZ) is used only for parcels where there is an above ground interest as in the case of condominiums. The Z value (01-99) indicates the level of the condominium unit within the building. A value of 01 is used for the very bottom level of a building.

Mapsheets at scales of 1"=200' and 1” = 300’ are identified using the 4 digit 10k number an alpha quad identifier of NE, SE, NW or SW to identify the quarter of the 10k Area of Interest.

How do I find the GPIN for a Property?

Customers can find the GPIN for a property by accessing one of our interactive mappers such as QuickInfo or County Mapper and entering in the property's address. The history of a property's GPIN can be traced through the Parcel History Tree.