Estimate rebar quantity, length, and weight
Use this rebar calculator to estimate bar count, total linear feet, and steel weight for concrete slabs and foundations.
Enter slab dimensions, choose spacing and rebar size, then adjust bar length and overlap if needed. Click Calculate to estimate total rebar needed.
For a 20ft × 20ft slab with 16-inch spacing using #4 rebar:
What size rebar should I use?
#3 or #4 for most residential slabs.
Why add overlap?
To maintain structural continuity between bars.