What unit of measusement is a drawing in and can it be converted?

I am measuring the diameter of a circle in one drawing and it gives a distance that is far larger than similar types of circles in other drawings. Well I type UNIT in the command prompt and it shows inches. I convert it to feet and remeasure the diameter and it still gives me the same large number! What do I need to change? How many of you use unitless for measuring versus feet or inches?

I read up on the Help files and it said that Architectural and Engineering scales are set to feet and inches.

I am also confused how to use the conversion tool on the QuickCalc in AutoCAD. The "Convert From" and "Convert To" are set to meters. I am not sure WHAT the default unit of measurement is to begin with.

AutoCAD uses two units: metric and imperial. There are five different types of imperial units: decimal, architectural, engineering, fractional and scientific.

Are you using a metric or imperial template?

The Unit is more of a way for AutoCAD to convert or scale one dwg to another when you insert or xref it into a dwg that has anout unit vale. Example you design a house using Architecture scale and unit of inches, you then xref that dwg into a civile site dwg that has a unit of Feet (civil guys use feet as the base), the two dwgs will be scaled to match. Once you assign a unit and create an object the one way to change the size is to scale the whole dwg with the scale command.

As for the QuickCal question, the QuickCal is only a built in calculator (in 2005) it does not change anything in the dwg. The Convert From and Convert To is say you have the From = inches and the TO = Feet ig you enter 36 as the value it returns 3 (36 inches = 3 feet) In 2005 (your profile says 2005) you can copy and paste that to "some fields" in the property palette not much more.

The only option in Units for Unitless, Inches, etc. is "Insertion Scale" and has nothing to do with measuring.

Set the units for measuring under "Length" and "Angle", the options there are Architectural, Decimal, Engineering, Fractional and Scientific for "Length" and Decimal Degrees, Deg/Min/Sec, Grads, Radians and Surveyor's Units for "Angle".

These settings are independent of the settings in the Dimstyles.

When changing units, AutoCAD only changes the type of unit, not the number of units. It does not do the conversion for you. A 12" dia. circle in a file set to inches will be a 12' dia. circle when you change the units to feet. When changing the units, you need to change the scale of the objects.

I am measuring the diameter of a circle...

Do you know what the diameter is supposed to be?

If so you can delete everything else and attach the file here.

Instructions to scale (or whatever is needed) will follow.

When changing units, AutoCAD only changes the type of unit, not the number of units. It does not do the conversion for you. A 12" dia. circle in a file set to inches will be a 12' dia. circle when you change the units to feet. When changing the units, you need to change the scale of the objects.

I just discovered this in AutoCAD MEP 2011 when changing units.

That's pretty cool, eh?