construction calculator
Rebar Grid Count & Spacing Calculator
Lay out a slab reinforcing mat: how many bars run each direction at a given spacing and edge cover, plus the total linear feet.
How it works
barsRunningLength = floor((width_ft x 12 - 2 x cover) / spacing) + 1 (each spans the length). barsRunningWidth = floor((length_ft x 12 - 2 x cover) / spacing) + 1 (each spans the width). total = barsRunningLength x length + barsRunningWidth x width.
Worked example
A 20 x 10 ft slab at 12 in on center, 3 in cover: 10 bars lengthwise + 20 bars widthwise = 400 linear ft.
When to use it
- Feed the total linear feet into the rebar weight calculator to order by weight.
- Cover is the clear distance from the slab edge to the first bar; 3 in is typical for slabs on grade.