? The so-called price per square foot generally refers to the average price of a painter's calligraphy and painting divided by the frame, which is a measure of the painter's painting level, so as to compare the market position of his works. The auction of calligraphy and painting should consider the author's artistic attainments, popularity, whether the painting is representative, whether it is a good work itself, age and so on. Frame scale is only one aspect. For reference, I hope to adopt it.