An adjustable scale typically used with a router table may be reset at any time to facilitate determining the change in height of the router regardless of where the scale is positioned when the router is at a given height. When used with a router table having a table plate with a height adjustment screw for adjusting the height of the router, the scale includes a marker carried by the table plate or the adjustment screw. When carried by the adjustment screw, the marker is rotatable relative to the adjustment screw to align markings thereon with a reference mark on the table plate to reset the scale. Thus, a zero marking may be aligned with the reference mark at any height of the router, and the adjustment screw and marker may then be rotated together to adjust the height of the router and simultaneously measure the height change.