Unit costs can vary for many reasons, including the following:

• Region (labor availability and skill).
• Size of the floor and the project.
• Formwork system (usually flat slabs are more economical to form than beams).
• Post-tensioning costs are not the same for different systems. Unbonded systems are often less expensive in some countries, but this may not be true if large bonded tendons are used in beams.
• Large diameter reinforcing bar is generally less expensive than small diameter bar for materials and labor.