We consider first the grading information provided by the publisher. Our Editors work to have consistency across our catalogs for ensemble and student-level music, so, therefore, we may adjust that level for advertising purposes.
For choral music, we consider a variety of elements, such as the length of phrase, range, tessitura, movement of vocal lines, diction challenges, range of dynamics and dynamic contrasts, the complexity of the rhythmic language, patterns that occur throughout the text, rhythm and vocal lines, key and or mode, harmonic language of the work, and language of the work.
For instrumental music, we consider range, rhythm, meter, independence of parts, phrasing, technical challenges presented to the instrumentalist, the complexity of the score, sections, or ensemble as a whole.