Geoprocessing considerations for length and area units

Many geoprocessing tools, including Spatial Join, Densify, and Generate Points Along Lines, have a parameter for specifying a linear distance and units. Several other tools, including Simplify Building and Subdivide Polygon, have a parameter for specifying an areal distance and units. These parameter types are commonly used for setting spatial tolerances and for applying a linear or areal interval at which some spatial action is undertaken.

In the Geoprocessing pane, both the Linear Unit and Area Unit parameters are displayed as a text box for a numeric value and a choice list of valid unit types. In Python, both parameter types are expressed as a string as a distance value and unit types, for example, "3.5 Kilometers".

The tables below provide information about the units of measurement used in geoprocessing tools. Each row provides the unit name found in tools in the Geoprocessing pane and its corresponding keyword for use in Python as well as a description.

Linear units

The following units are available for the measurement of length:

Data typePython keywordDescription

Kilometers

Kilometers

1,000 meters.

Meters

Meters

Metric base unit of distance.

Decimeters

Decimeters

0.1 of a meter.

Centimeters

Centimeters

0.01 of a meter.

Millimeters

Millimeters

0.001 of a meter.

International Nautical Miles

NauticalMilesInt

1,852.0 meters.

Statute Miles

MilesInt

1,609.344 meters.

International Yards

YardsInt

0.9144 meters.

International Feet

FeetInt

0.3048 meters. Required for new coordinate systems used by U.S. government agencies beginning in 2023.

International Inches

InchesInt

0.0254 meters.

US Survey Nautical Miles

NauticalMiles

1,853.248 meters.

US Survey Miles

Miles

63,360.0/39.37 meters.

US Survey Yards

Yards

36.0/39.37 meters.

US Survey Feet

Feet

1,200/3937 meters or 0.3048006096012192. Used in existing U.S. coordinate systems based on NAD27 and NAD83. Usage will be phased out starting in 2023.

US Survey Inches

Inches

1.0/39.37 meters.

Decimal Degrees

DecimalDegrees

Angular unit of measure based on 1/360 of a circle. The actual length of a degree depends on its location on the spherical or ellipsoidal model that is being used.

Points

Points

0.0254/72.0 meters.

Area units

The following units are available for the measurement of area:

Data typePython keywordDescription

Square Kilometers

SquareKilometers

Area of a square 1 kilometer per side

Hectares

Hectares

Standard metric unit of land area as defined by a square 100 meters per side

Ares

Ares

Area of a square 10 meters per side

Square Meters

SquareMeters

Area of a square 1 meter per side

Square Decimeters

SquareDecimeters

Area of a square 1 decimeter per side

Square Centimeters

SquareCentimeters

Area of a square 1 centimeter per side

Square Millimeters

SquareMillimeters

Area of a square 1 millimeter per side

Square Statute Miles

SquareMiles

Area of a square 1 Statue mile per side

International Acres

Acres

Area of 4046.8564224 square meters

Square International Yards

SquareYards

Area of a square 1 international yard per side

Square International Feet

SquareFeet

Area of a square 1 international foot per side

Square International Inches

SquareInches

Area of a square 1 international inch per side

Square US Survey Miles

SquareMilesUS

Area of a square 1 US Survey mile per side.

US Survey Acres

AcresUS

Used when working with US Survey feet and equal to 43,560 square U.S. Survey Feet or 4,046.872 square meters

Square US Survey Yards

SquareYardsUS

Area of a square 1 US Survey yard per side

Square US Survey Feet

SquareFeetUS

Area of a square 1 US Survey foot per side

Square US Survey Inches

SquareInchesUS

Area of a square 1 US Survey inch per side


In this topic
  1. Linear units
  2. Area units