Frame rate (also known as frame frequency) is the frequency (rate) at which an imaging device produces unique consecutive images called frames. The term applies equally well to computer graphics, video cameras, film cameras, and motion capture systems. Frame rate is most often expressed in frames per second (FPS), and is also expressed in progressive scan monitors as hertz (Hz).

The human eye and its brain interface, the human visual system, can process 10 to 12 separate images per second, perceiving them individually. The visual cortex holds onto one image for about one-fifteenth of a second, so if another image is received during that period an illusion of continuity is created, allowing a sequence of still images to give the impression of motion. Early silent films had a frame rate from 14 to 24 FPS but by using projectors with dual- and triple-blade shutters the rate was multiplied two or three times as seen by the audience. Thomas Edison said that 46 frames per second was the minimum: "anything less will strain the eye." In the mid- to late-1920s, the frame rate for silent films increased to about 20 to 26 FPS. When sound film was first introduced in 1926, variations in film speed were no longer tolerated as the human ear was more sensitive to changes in audio frequency. From 1927 to 1930, the rate of 24 FPS became standardized for 35 mm sound film; a speed of 455 millimetres (17.9 in) per second. This allowed for simple two-blade shutters to give a projected series of images at 48 per second. Many modern 35 mm film projectors use three-blade shutters to give 72 images per second—each frame flashed on screen three times.