Abstract: A hardness tester includes a frame with a penetrator slidably carried by said frame for movement along a penetration axis, and thereby adapted to form an indentation in a specimen upon application of a load thereto. The resulting depth of the indentation is determinative of the hardness number of the specimen. The means by which a load is applied to the penetrator is rotatably actuated. The rotational displacement of the loading means bears a predetermined relationship to the linear dimension of the indentation depth formed during hardness testing of a specimen. The hardness tester further includes electro-optical mechanical encoding means, and further adapted to emit a coded electrical signal indicative of the sensed angular displacement. Furthermore, an electronic counting circuit decodes the output signals of the encoding means in the form of a count. The count, determinative of the resulting depth of penetration, is indicative of the hardness number of the tested specimen.