The next most obvious property of paper is it's caliper (thickness) which is measured by a micrometer and is expressed in millimetres (previously in thousandths of an inch). This is mostly determined by the paper grammage but it is also affected by the paper finish. Thus, all other things constant, a Smooth Finish paper will be thinner than a Medium Finish paper, and a Medium Finish paper will he thinner than a Rough Finish paper. (See Article No. 9 re Surface Texture)
Caliper is also affected by the pulp furnish and by beating. Thus course pulp fibres will result in a thicker paper than will fine fibres. Also the longer the pulp is beaten and the heavier the loading of the beater roll, the more compact and thinner the paper made from it will become.
Formation also affects caliper. A very "wild" formation will result in a thicker paper than will a very uniform formation.