Rebar Calculator
Computes the number of bars running each way for a single layer grid when you know inside dimensions and spacing.
Step 1: Units
Step 2
Enter project measurements
Use decimals if needed (e.g. 3.5).
How to use this calculator
Enter clear span inside the forms and center-to-center spacing. The tool assumes bars run full length in each direction with one bar on each edge.
What the math is doing
Bars in a direction ≈ floor(length / spacing) + 1. Total pieces = bars along length + bars along width for one layer.
Frequently asked questions
What about lap splices?
Add extra length at the steel yard; this tool counts pieces, not lap lengths.
Two layers?
Run the calculator twice with the same grid or multiply by two after checking chair heights.
Epoxy or black bar?
Counts are the same; pricing differs.
Is this code-compliant?
Always follow the structural drawing and local building code.