Abstract: A dovetail tenon offset caliper includes a shoulder engagement member, a interior intersection point engagement member and a translation assembly for displacing the interior intersection point engagement member with respect to the shoulder engagement member to measure the offset necessary to construct a dovetail tenon to fit a particular dovetail mortise. The translation assembly is configured to displace the interior intersection point member with respect to the shoulder engagement member along a line substantially parallel to the mortise base to measure the perpendicular distance between a first plane perpendicular to the displacement line, the first plane containing the reference shoulder, and a second plane, parallel to the first plane and containing the intersection point, this distance being the dovetail tenon offset. The measured offset is used to position a dovetail cutting tool, such as a router bit.