How is width in inches calculated from an image's width in pixels and PPI?

• A. Width in inches equals the pixel width times PPI.
• B. Width in inches equals PPI divided by the pixel width.
• C. Width in inches equals the pixel width added to PPI.
• D. Width in inches equals width in pixels divided by PPI.

Answer: (D)

Converting pixels to inches relies on how many pixels fit into one inch, which is the PPI (pixels per inch) value. PPI tells you the density of the image: how many pixels occupy each inch of physical space. So the physical width is the pixel width divided by the PPI. In formula form: width in inches = width in pixels ÷ PPI. For example, 1920 pixels wide at 96 PPI is 1920 ÷ 96 = 20 inches; at 300 PPI, the same 1920-pixel width becomes 1920 ÷ 300 = 6.4 inches. This shows why the same pixel count yields different physical sizes depending on density.