In this study, the effects of blast furnace slag (BFS) and calcite on rheological properties of self-compacting concrete (SSC) in meso and macro scales were investigated. During the preparation of replicate samples, while BFS was replaced with the cement at the rate of 10%, 20%, 30%, and 40% by weight, calcite was added to the cement at the rate of 10%, 15%, 20%, and 25% by weight. The rheological properties (plastic viscosity and yield point) and mini-slump flow values of the cement paste prepared in meso scales were determined. The fresh flow consistency of concrete prepared in macro-scale was tested with L-box flowing test. As a result, upon evaluating the rheological parameters of the pastes according to the Bingham model, while the pastes with a plastic viscosity value close to 1 Pa·s (±100 MPa·s) and a mini-slump flow rate higher than 200 mm were observed to be more resistant to segregation and form a homogeneous flow consistency, their L-box flowing rates were determined to be homogeneous and high. Ideal SSCs were made by adding 20% and 25% calcite to 30% BFS and 40% BFS replaced mixtures respectively in this study. It was also concluded that ideal SCC could be produced with paste mixtures having 1 Pa·s (±100 MPa·s) viscosity and mini-slump flow diameter higher than 200 mm. With the increase in calcite addition rates in SSCs, the passing rate for the L box test has increased.