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Rebar Calculator
Enter the slab and the grid spacing. This returns the total steel, how many sticks that is at standard lengths, and the weight for pricing.
Your numbers
Result
Rebar needed
1,212
linear ft
- Sticks to order
- 61sticks
- Total weight
- 809lb
- Grid length before laps
- 1,122linear ft
- Bars across
- 19bars
- Bars along
- 23bars
- Intersections to tie
- 437ties
- Slab area
- 720sq ft
How this is calculated
- Bars each way = slab dimension ÷ spacing, plus one for the far edge.
- Grid length = (bars across × slab length) + (bars along × slab width).
- With laps = grid length × (1 + lap allowance). Splices are typically 40 bar diameters.
- Weight = linear feet × pounds per foot for the bar size.
Before you order
- Rebar has to sit in the middle third of the slab, on chairs. Steel lying on the subgrade does nothing structurally and is a very common shortcut.
- Cover matters: concrete cast against earth needs 3 in of cover, formed surfaces exposed to weather need 1.5 to 2 in. Too little cover and the steel rusts and spalls the slab.
- Bar size and spacing are engineering decisions for anything structural. This calculates a grid you specify; it does not design one.
- Welded wire mesh is a different product with different placement rules and is not covered here.
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