Complexity is the biggest factor in determining the cost of embroidery digitizing. A large circle that is all fill makes the stitch count very high, but the design is simple. A large circle that has a complex design inside, but is not completely filled has a lower stitch count, but is much more time consuming to digitize.
Not all designs or logos are embroidery friendly because they were originally designed for print. With print, letters can be much smaller and colors can be incorporated into each other more fluidly than with embroidery. Therefore, sometimes modifications must be made to the size and /or layout of lettering, logo, or design to achieve the best results (with your approval of course).
Sometimes, the smallest text in a design or logo will dictate the size that it can be embroidered. The smallest text we can embroider with any legibility is about .25" in height. Depending on the size, some designs, images or logos with intricate detail will need to be reduced in complexity to attain high quality embroidery.