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 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.
To calculate an area you define
- 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
- At the Command prompt, enter o (Object).
- Select an object.
The area and perimeter of the selected object
display in the current units format.
To add an area as you calculate
- Enter a (Add).
- Do one of the following:
- Press Enter twice to end the command.
To subtract an area as
you calculate
- While a combined area displays, enter s (Subtract).
- 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.
- Press Enter to end the command.
CommandsAREALIST
Displays property data
for selected objects.
MASSPROP
Calculates
the mass properties of regions or 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 VariablesAREAPERIMETER
Stores the last perimeter
value computed by the AREA or LIST command.
