This thesis is about how different concrete quality in foundation slabs affects the reinforcement content and the drying time. Changing the concrete quality also changes the reinforcement content and drying time. Its common that a change of concrete quality is requested by the contractor to avoid delays and thus making financial savings. But changing concrete quality can lead to problems if the changes in the reinforcement content are not taken into account. Foundation slabs are sensitive structural parts that are exposed to creep and shrink deformations. These deformations can cause cracks in reinforced foundation slabs.The purpose of this thesis is to study the effects that result from the increase of the concrete strength, to show the difference that occurs in the amount of the reinforcement and the time required for the concrete to dry out.To solve this, a calculation template have been developed based on MathCAD in which slabs on soil with different thicknesses and different concrete qualities were analyzed with respect to the reinforcement amounts and drying time. Two different concrete grades were used in the work, one was concrete C30-37, and the other was C45-55.Results show that an increase in the concrete quality of the slab on the ground leads to an increase in the reinforcement content that the slab needs and leads to a reduction in the drying time needed. This leads to an increase in the cost of the slab that has been cast. An example is a slab on the ground with a thickness of 150 mm, the amount of the reinforcement has increased by 19%, concrete cost has increased by 11.64% but drying time has decreased by 70%.