# Segment length

Specees treats every line between two anchor points in Illustrator as a segment. Toggle on " Specifies the segment length " to measure the length of a segment, whether it is a straight line or a curved line.

The position buttons will have no effect when measuring the segment length.

##### Why can't the value of a curved segment's length be 100% accurately measured?

The reason is a curve in Adobe Illustrator is made of 2 anchor points and 1 or 2 handles, and we simply cannot find a Mathematical formula to measure it accurately. The way we measure it now is to divide the curve into many small segments and measure each segment's length as a straight line. Therefore, the result is very close to the actual value (99.986% accurate)*. If you compare the results with those in Illustrator's Document Info Panel > Objects, you will notice that our results are basically the same as those calculated by Illustrator. Therefore, we think this should be an acceptable solution for measuring the length of a curve. Unless your work demands a very high accuracy in the length of a curve, we think that should be ok to use.

*How do we come up with 99.986% accuracy? We take the arc of 1/4, 1/8, and 1/16 of a circle and record the results made by Specees. Then, we compare them with the results of calculating them in a simple Mathematical way: 2 x radius x pi, then divided by 4/8/16. The differences are around 0.014%, so we conclude that it is 99.986% accurate.