Abstract: A vernier gauge has three arc members, two flat pieces and two sliding pieces. A second arc member is slidably engaging with a first arc side of a first arc member from a first end of the first arc member and a third arc member is slidably engaging with a second arc side of the first arc member from a second end of the first arc member. Each of two free ends of the second and third arc members is actively attached one of the two flat pieces each of which is slidably engaged with one of the two sliding pieces. The second, third arc members and the two flat pieces are provided with main scales and the first arc member and the two sliding pieces are provided with corresponding vernier scales. Each of the two sliding pieces is further provided with two opposite tips and a flat surface. Such gauge can permit accurately fractional readings of angles as well as inner or outer diameters of objects and of depths of objects when the flat piece is solely used.