Example scenarios
| Units | L × W | Grid X/Y | Chair spacing | Mats | Mode | |
|---|---|---|---|---|---|---|
| US | 20 × 15 ft | 12 × 12 in | 4 ft | Top | Full grid | |
| Metric | 6 × 4 m | 200 × 200 mm | 1.2 m | Top + Bottom | Full grid, staggered | |
| US | 30 × 20 ft | — | 3 ft (perimeter) | Top | Perimeter only |
Click “Load” to populate inputs, then press Calculate.
Results
| Metric | Value |
|---|---|
| No results yet. Enter values and click Calculate. | |
Formula used
- Bars in X (along length) = ⌊width / sX⌋ + 1.
- Bars in Y (along width) = ⌊length / sY⌋ + 1.
- Chairs per bar (base rows) = ⌊length / sC⌋ + 1.
- Chairs per bar (staggered rows) = ⌈length / sC⌉ when offset by sC/2.
- Perimeter-only chairs ≈ ⌈Perimeter / sP⌉, where Perimeter = 2·(L + W).
- Total per mat = sum over supported directions × row counts.
- Grand total = ⌈(Total per mat × number of mats) × (1 + waste%)⌉.
How to use
- Select units and enter slab length and width.
- For full-grid mode, set bar spacings and chair spacing along bars.
- Choose mats to support and which bar runs receive chairs.
- Enable perimeter-only mode for edge runs and set perimeter spacing.
- Apply waste percentage, then click Calculate and export results.
FAQs
Bars along a direction equal floor(orthogonal dimension ÷ grid spacing) + 1. Chairs along a bar equal floor(bar length ÷ chair spacing) + 1, with optional staggering adjustments.
Staggering offsets every second row by half the chair spacing. Some rows may need one fewer chair depending on slab length relative to spacing.
Use it for situations like edge T-spacers, curb runs, or when interior support is handled by other accessories. Set an appropriate perimeter spacing for continuous edge support.
Cover is the distance from concrete surface to steel. Chair height is chosen to achieve the specified cover for the selected bar size and mat elevation.
This tool provides planning estimates. Always verify final placement and support types against project specifications, local codes, and manufacturer recommendations.