This article contains practical information on the design and dimensioning of prestressed concrete solid flat slabs using unbonded post-tensioned tendons, in accordance with the European standard EN 1992-1-1 and German standard DIN 1045-1. The calculation method and the mathematical equations necessary for the dimensioning of the non-adherent unguided tendons are given. The paper presents a case study where a slab floor is dimensioned for deflection using prestressing only in the column strips. The deflection of the slab is calculated using equivalent loads (unguided tendon), a mixt tendon profile with 4th degree curve segments (unguided tendon) and parabolic tendon profile with 2nd degree curve segments (guided tendon-classical solution).