Abstract: The invention relates to a setting gauge (21) for setting a depth stop (6) on a handpiece (1), which has a connection device (3) for the releasable connection of a pin-shaped tool (4) with the handpiece (1), in particular for setting a depth stop (6) on a handpiece (1) for a working of a root canal (W2) in a tooth (Z). So that the setting of the depth stop can be effected more simply and with little manual effort, the setting gauge (21) has a connection element for connecting and positioning the setting gauge (21) on the handpiece (1) and at least one scale (27a, 27b, 27c) on the setting gauge body (22) which, in the position of the setting gauge (21) connected with the handpiece (1), extends parallel to the depth stop (6) and its setting path.