How long does two inches mean?

Inches are municipal units of length. 10 inch equals 1 foot, 1 inch equals 3 or 33 centimeters, and 1 meter equals 30 inches. Size: Two-inch photos generally refer to 3.5*5.4cm 2-inch photos, and the corresponding pixels are 626*4 13. There is also a small 2-inch photo of 3.3*4.8cm (for passport), and the corresponding pixel is 567*390.

Generally speaking, when we say a few inches of photos, we mean the length of inches on the long side of the photos. 1 inch = 2.54 cm. So a two-inch photo = 2.54 * 2 = 5.08cm.. According to the use requirements of different photos, the general standard two-inch photo is 3.5 * 5.4cm；; Passport, as required, is 3.3*4.8cm.

Introduction of length unit

The unit of length refers to the basic unit for measuring spatial distance, which is formulated by human beings to standardize the length. Its international unit is "meter" (symbol "m"), and commonly used units are millimeter (mm), centimeter (cm), decimeter (dm), kilometer (km), meter (m), micron (micron) and nanometer (nm). Length units play an important role in various fields.

The unit of length "meter" in the international system of units originated in France. 1790 In May, a special committee composed of French scientists suggested that one fortieth of the total length of the earth meridian passing through Paris should be used as the unit of length-meter, and 179 1 year was approved by the French Parliament. In order to make a reference device to represent the value of rice, under the leadership of French astronomers Telebul and Mishin.

1792 to 1799, from Dunkirk to Barcelona. 1799, according to the measurement results, a 3.5 mm× 25 mm short-section platinum rice rod was made, and the distance between the two ends of the rod was set as 1 m, which was kept by the French archives, so it was also called "archival rice", which was the earliest definition of rice.