Obtain Area and Mass Properties Information

You can obtain the area, perimeter, and mass properties defined by selected objects or a sequence of points.

You can calculate the area and perimeter of a sequence of points. You can also obtain the area, perimeter, and mass properties of any of several types of objects.

TipA fast way to calculate an area bounded by several objects in 2D is to use the BOUNDARY command. With BOUNDARY, you can pick a point within the area to create a closed polyline or region. You can then use the Properties palette or the LIST command to find the area and perimeter of the polyline or region.

Use Commands to Calculate Area

With the MEASUREGEOM and AREA commands, you can specify a series of points or select an object to calculate area. If you need to calculate the combined area of multiple objects, you can keep a running total as you add or subtract one area at a time from the selection set. You cannot use window selection or crossing selection to select objects.

Total area and perimeter are saved in the AREA and PERIMETER system variables.

In addition to area, with the MEASUREGEOM command, you can obtain geometric information from objects such as distance, radius, angle, and volume.

Define an Area

You can measure an arbitrary closed region defined by the points you specify. The points must lie on a plane parallel to the XY plane of the current UCS.

Calculate the Area, Perimeter, or Circumference of an Object

You can calculate the enclosed area and perimeter or circumference of circles, ellipses, polylines, polygons, regions, and AutoCAD 3D solids. The information displayed depends on the type of object selected:

  • Circles. Area and circumference display.
  • Ellipses, closed polylines, polygons, planar closed spline curves, and regions. Area and perimeter display. For wide polylines, this area is defined by the center of the width.
  • Open objects such as open spline curves and open polylines. Area and length display. Area is calculated as though a straight line connects the start point and endpoint.
  • AutoCAD 3D solids. Total 3D area for the object displays.

Example: How Various Areas Are Calculated

Combined Areas

Calculate Combined Areas

You can calculate the total area of multiple areas by specifying points or by selecting objects. For example, you can measure the total area of selected rooms in a floor plan.

Subtract Areas from Combined Areas

You can subtract more than one area from a combined area as you calculate. For example, if you have calculated the area of a floor plan, you can subtract the area of a room.

Example: Subtraction of Areas from a Calculation

In the following example, the closed polyline represents a metal plate with two large holes. The area of the polyline is first calculated and then the area of each hole is subtracted. The area and perimeter or circumference of each object displays, with a running total after each step.

The Command prompt sequence is

Command: area

Specify first corner point or [Object/Add/Subtract]: a

Specify first corner point or [Object/Subtract]: o

(ADD mode) Select objects: Select the polyline (1)

Area = 0.34, Perimeter = 2.71

Total area = 0.34

(ADD mode) Select objects: Press Enter

Specify first corner point or [Object/Subtract]: s

Specify first corner point or [Object/Add]: o

(SUBTRACT mode) Select objects: Select the lower circle (2)

Area = 0.02, Circumference = 0.46

Total area = 0.32

(SUBTRACT mode) Select objects: Select the upper circle (3)

Area = 0.02, Circumference = 0.46

Total area = 0.30

(SUBTRACT mode) Select circle or polyline: Press Enter

Specify first corner point or [Object/Add]: Press Enter

You can also use REGION to convert the plate and the holes to regions, subtract the holes, and then use the Properties palette or the LIST command to find the area of the plate.

TipUse the CAL command or QuickCalc calculator to convert from one system of area units to another. For more information, see Use the QuickCalc Calculator.

Calculate Mass Properties

With the MASSPROP command, you can analyze 3D solids and 2D regions for their mass properties including volume, area, moments of inertia, center of gravity, and so on. In addition, the result of the computations can be saved to a text file.

Procedures
To calculate an area you define
  1. Click Home tabUtilities panelMeasure drop-downArea. At the Command prompt, enter area.
  2. Specify points in a sequence that define the perimeter of the area you want to measure. Press Enter.

    The first and last points connect to form a closed area. The area and perimeter display in the current units format.

To calculate the area of an object
  1. Click Home tabUtilities panelMeasure drop-downArea. At the Command prompt, enter area.
  2. At the Command prompt, enter o (Object).
  3. Select an object.

    The area and perimeter of the selected object display in the current units format.

To add an area as you calculate
  1. Click Home tabUtilities panelMeasure drop-downArea. At the Command prompt, enter area.
  2. Enter a (Add).
  3. Do one of the following:
    • Specify points to define the area you want to add. Press Enter.
    • Enter o (Object) and select the objects you want to add.

      Each new area and a running total of all areas displays in the current units format.

  4. Press Enter twice to end the command.
To subtract an area as you calculate
  1. While a combined area displays, enter s (Subtract).
  2. Do one of the following:
    • Specify points to define the area you want to subtract. Press Enter.
    • Enter o (Object) and select the objects you want to subtract.

    The running total of all areas updates and displays as you define new areas.

  3. Press Enter to end the command.
Commands
AREA

Stores the last area computed by the AREA command.

LIST

Displays property data for selected objects.

MASSPROP

Calculates the mass properties of regions or AutoCAD 3D solids.

MEASUREGEOM

Measures the distance, radius, angle, area, and volume of selected objects or sequence of points.

PROPERTIES

Controls properties of existing objects.

QUICKCALC

Opens the QuickCalc calculator.

UNITS

Controls coordinate and angle display formats and precision.

System Variables
AREA

Stores the last area computed by the AREA command.

PERIMETER

Stores the last perimeter value computed by the AREA or LIST command.