a flat (square) foot =33.3cm×33.3cm length× width× 9 = square foot
Example: four feet of paper? 1.36m*.68m*9=8.32 square feet. Basis: 1 square meter equals 9 square feet, with the meter as the calculation unit.
Extended information
One square foot is referred to as one square foot or one foot for people in antique shops. Calculating the square foot of a painting is the product of the length multiplied by the width of the painting divided by the fixed square foot size of 118.89, and the square foot size is naturally known. Specific to raw propaganda and cooked propaganda, the specifications of different grades of paper from different paper mills are somewhat different.
the conversion formula between centimeters and square feet: (length cm × width cm)× .9 = square feet. Hong Kong is measured in square feet, and one square meter in the Mainland is about 1.7 square feet in Hong Kong. General square feet, also called square feet, is an English unit of area. 1 square foot ≈929.34 square centimeter =144 square inch ≈ .11111111 square yard ≈.92934 square meter.
In China people's "calligraphy and painting" transactions, the first question is the price: How much is a foot? The "ruler" mentioned here, that is, the square ruler, is used to calculate the size and area of calligraphy and painting. The ruler is an ancient unit of length in China, and it is still in use today. The transaction mode of calligraphy and painting works valued by "ruler" comes from the finished size of rice paper. Specifications are: eight feet, six feet, five feet, four feet, three feet, and those exceeding one foot are called one foot two feet, one foot six feet, and one foot eight feet; Uses: strip, batch, couplet, bucket, etc.
I'm afraid it's impossible to verify when the history of valuing Chinese calligraphy and painting works by "ruler" began. Zhang Yanyuan, a Tang Dynasty man, said in "Records of Famous Paintings of Past Dynasties": "Dong Boren, Zhan Ziqian, Zheng Fashi, Yang Zifa, Sun Shangzi, Yan Liben and Wu Daozi have a screen worth 2, yuan, and the second one sells for 15, yuan. Yang Qidan, Tian Sengliang, Zheng Falun, Er Monk, and Yan Lide, all of whom are worth 1, yuan and well-known in customs. " In the middle of Qing Dynasty, Zheng Banqiao, one of the Eight Eccentrics in Yangzhou, retired to paint in his hometown, and once listed his own charging standards.
that is, six taels in a large scale, four taels in a medium scale, two taels in a small scale, and one or two couplets in a book. Five yuan for a fan and a bucket. It is better to give gifts and food than silver. What is sent by the public may not be what the disciples like. During the Republic of China, a large number of painters and calligraphers, such as Qi Baishi, Zhang Daqian, Wu Hufan, Feng Chaoran and Tao Lengyue, also set their own prices by the "ruler".
Reference: Baidu Encyclopedia-a leveling ruler.