Hagaki printing refers to a variety of print sizes. Strictly speaking, Hagaki paper is a postcard-sized paper that measures 4 inches by 4 inches. However, the Hagaki print setting on some printers is equivalent to the Japanese postcard size, which measures 3.94 inches by 5.83 inches.
The Japanese word "hagaki" means "postcard" in English. It strictly refers to a square print of 4 inches. However, the Japanese postcard setting on many commercial printers refers to a different size. In Japan, the PC size refers to a print measuring 3.9 inches by 5.8 inches, while the KG size, also known as 4R, refers to a print measuring 4 inches by 6 inches. Adding further to the confusion is the fact that prints double the size are also known as the Japanese postcard size. The Ofuku Hagaki size is twice the PC size, while the 6R or 8P size is twice the KG size.