Abstract: A log gauge for a chain saw is provided which enables an operator to repeatedly cut approximately equal lengths of firewood logs with only a minimal amount of effort being required to visually measure the logs. This accomplished by a mirror that is affixed to one leg of a frame member while the other leg is secured to the handle of the chain saw. The mirror is adjusted by an adjusting bolt so the operator can align on a visual indicator relative to the image of the end of the log in the mirror with respect to a scribed line on the mirror. One embodiment of the frame is formed by utilizing a unitary flexible plastic frame with a C-shaped bridge having a reduced cross sectional area that allows one leg to flex relative to the other thereby allowing the operator to adjust the mirror for different lengths of logs.