The sizing chart shows the finished measurements for a garment laid
flat. For example the 3XL shows the chest measurement of 27” - this represents the measurement from arm
pit to arm pit on one side. So the finished garment would have a circumference of 54”.
To get a perfect fit you could measure one of your favorite tops and
then find the closest measurements on the size chart.
The length measurement is from the top of shoulder
to bottom hem.