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HeizerDesk 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. It is a free Rebar Calculator for concrete work, with the formula printed below the answer.
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.