Finger (unit)

[Exactly which part of the finger should be used is not defined; the width at the base of fingernail (#6 in the sketch) is typically less than that at the knuckle (#5).]

the fingerbreadth (literally the width of a finger) is an informal but widely used unit of measure.

[3][4] In the measurement of distilled spirits, a finger of whiskey refers to the amount of whiskey that would fill a glass to the level of one finger wrapped around the glass at the bottom.

"[8][9] Finger is also the name of a longer unit of length, used historically in cloth measurement, to mean one eighth of a yard or 4⁠1/2⁠ inches.

These units have no legal status but remain in use for 'rough and ready' comparisons.

Some hand-based measurements, including the finger.