Rebar Calculator
NEWCalculate rebar needed for concrete slabs and foundations. Get total linear feet, number of bars, weight, and ties/chairs needed for grid patterns.
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How to use Rebar Calculator
- Select rebar size (#3-#8) and unit system, then enter slab length and width.
- Set the on-center spacing and standard bar length (20, 40, or 60 ft).
- Click Calculate for total linear feet, bars needed, weight, and tie/chair estimates.
What is Rebar Calculator?
A rebar calculator determines how much reinforcing steel (rebar) is needed for a concrete slab or foundation. Rebar is placed in a grid pattern at specified spacing to reinforce the concrete against tension and cracking.
This calculator supports rebar sizes #3 through #8, configurable spacing, and calculates in both directions for grid patterns. It also estimates the number of standard-length bars needed and total weight for ordering.
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FAQ
- What rebar size should I use for a residential slab?
- For standard residential slabs (4-6 inches thick), #4 rebar at 12-18 inch spacing is typical. For driveways or heavier loads, use #5 rebar.
- What spacing should rebar be placed at?
- Common spacing is 12, 16, or 18 inches on center. Use 12 inches for heavy loads, 16-18 inches for standard residential slabs.
- How long are standard rebar lengths?
- Standard rebar comes in 20, 40, and 60 foot lengths. 20-foot bars are most common for residential projects. Longer bars reduce the number of overlaps needed.
- How much does rebar weigh?
- Rebar weight depends on size: #3 = 0.376 lb/ft, #4 = 0.668 lb/ft, #5 = 1.043 lb/ft, #6 = 1.502 lb/ft. Multiply pounds per foot by total linear feet for total weight.
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