Unlike AutoCad, Illustrator works in paper space units. Essentially, the length of a line segment in Adobe Illustrator is its length on the piece of paper, not the length at full scale. Therefore, to scale a drawing accurately in Illustrator, you will have to do a little conversion.
Step 1: Click on the line tool. Find a line segment in Illustrator that you know the length of. It can be the length of a wall. The longer the length that you choose, the more accurate the scale will be. You do not want to scale an entire drawing off a door width or a piece of furniture for example. Draw a new line over the original line and a small gray window will show the distance in Inches on the piece of paper. Write this number down. Also write down the length of this line segment in actual scale (real life). Example: 80 feet.
Step 2: Decide on the scale of the drawing. This should be based on the the plot size (paper size) and the size of the drawing. Examples of commonly used architectural scales are 1/8″ = 1′ ; 1/4″ = 1′ ; 1/2″ = 1′. You can also use engineering scales such as 1:100 where one drawing unit equals 100 units in actual size.
Step 3: Convert the distance of the line segment you measured in step 1 to the scale you decided on in step 2. For right now, let’s focus on the distance of the line segment in real life. We’ll use 80 feet as an example. Say you decided to use an architectural scale of 1/8″ = 1′. Therefore 80 feet times 1/8″ (which equals 1′ in paper space) equals 10″ on the drawing. To multiply, I converted 1/8″ to 0.125.” Now you know that that line segment that you found in Step 1 needs to be 10″.
Step 4: Divide the amount that the line segment needs to be (the number you found in step 3) by the length of the line segment you found in Step 1 on the drawing itself (Length of Line Segment to Scale) / (Current Length of Line Segment in Adobe Illustrator paper space). Disregard the length of the line segment in actual scale. You already did that calculation in Step 3. Once you divide these two numbers, you will get a decimal number. Write this number down. Let’s just say it’s 0.872 for example.
Step 5: Select the entire drawing. Select the “object” menu, then “transform” and then “scale”. A pop up window will appear. Adobe Illustrator does scales by percents not by decimals. So if the number you got in Step 4 was 0.872, you will scale the drawing at 87.2%. And if it was 1.223, you would scale it at 122.3%. Just remember that 1 is 100% so the conversion between decimal and percent will come naturally.
Step 6: Check the line segment on the drawing to make sure the it is scaled correctly. If the 80′ length measures 10″ on the drawing, you scaled it correctly. If it measures slightly off, then you will have to repeat this process to get it more precise. Possible reasons for errors include not accurately measuring the line segment, picking too small of a line segment, or not recording enough decimals. The more decimals you record, the more precise the scaling will be.
