There are quite a few ways to accomplish this and I am going to show you a little trick to find area in acres quickly. The reason I am writing this is to show you some of the capabilities AutoCAD has when it comes to doing calculations.
Type AREA in the command line and you will get this prompt:
Specify first corner point or [Object/Add/Subtract]:
You can pick points or select an object and add/subtract to find the area you need.
NOTE: The AREA command stores the last calculation in a system variable also called AREA. To see this, type SETVAR on the command line, then type AREA. It will show you the stored value of the last AREA command calculation.
Depending on the units you are using, you will need to first find the formula 1 acre = X units. I often use Google to calculate unit conversions. Then divide the value found in the AREA command by value X shown in the conversion.
For example, if you calculated the area in feet you would divide the total area by 43560 to get the acreage.
Or…since it’s way too much work to copy & paste, let alone, type the area into a calculator (tongue-in-cheek), you could type CAL on the command line and at the Expression prompt, type:
Let’s break this formula down:
GETVAR(area) is an AutoLISP expression that returns the value produced by the AREA command. The forward slash (/) means “divided by”. The 43560 value is X (in this case shown in feet) in the formula 1 acre = X units.
I can hear you saying, “I’ll never remember that!” I hear you. So why not turn this into a custom macro button so you can forget this expression and still use it whenever you need it (after you run the AREA command first, of course):
Of course there is probably a free AutoLISP program out there that could do the trick as well. If you know of any, feel free to share it with me.