Reinforcement Mesh Count Calculator
Prefabricated reinforcing mesh (reo fabric) is sold in fixed-size sheets that must overlap at their edges so the reinforcement is continuous.
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Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.
How to use this calculator
- Enter the slab length and width in metres — the plan area to be reinforced.
- Enter your mesh sheet size (a common reo sheet is 6.0 m × 2.4 m) and the lap per lapped edge in mm; leave blank to use 6.0 × 2.4 m and a 200 mm lap.
- Optionally add a wastage percentage for cutting around edges and openings, then read the number of sheets to order.
How it works
Prefabricated reinforcing mesh (reo fabric) is sold in fixed-size sheets that must overlap at their edges so the reinforcement is continuous. The overlap (lap) means each sheet covers less than its full area. This calculator models the usable coverage as the sheet dimensions minus one lap in each direction: usable area = (sheet length − lap) × (sheet width − lap). The number of sheets is the slab area divided by that usable area, multiplied by (1 + wastage%), then rounded UP to a whole sheet.
This is a deliberately simple area-based estimate. It does not solve the exact sheet-by-sheet layout, so it will not perfectly match a set-out drawing where sheets are staggered or trimmed to fit. Sheet orientation, cutting around columns and penetrations, and edge trims all change the real count. Treat the result as a purchasing estimate and confirm the reinforcement grade, sheet size and lap against the structural drawings, the mesh manufacturer's data and the relevant standard (e.g. AS/NZS 4671, Eurocode 2 or ACI 318) — this is guidance only, not a structural design.
Worked example
12 m × 8 m slab with SL-type mesh sheets. A 12 m × 8 m ground slab (96 m²) is reinforced with 6.0 m × 2.4 m mesh sheets, lapped 200 mm per edge and with no extra wastage. Each sheet gives an effective (6.0 − 0.2) × (2.4 − 0.2) = 5.8 m × 2.2 m = 12.76 m² of usable coverage. 96 ÷ 12.76 = 7.52, which rounds up to 8 mesh sheets. That is 8 × 14.4 m² = 115.2 m² of mesh purchased for 96 m² of slab — the difference is the laps. Add a couple of spare sheets for cutting around edges and penetrations.
Common mistakes
- Mixing units — entering the slab in metres but the lap in metres (e.g. 0.2) instead of millimetres. The lap field is in mm; 200 means 200 mm = 0.2 m.
- Forgetting the lap entirely. With no overlap the count is too low, because real sheets must overlap to stay continuous — always include the manufacturer's specified lap.
- Assuming the effective-coverage estimate equals the exact site layout. It is a purchasing estimate; the set-out drawing and cutting around penetrations can push the real count up, so order spare sheets.
Frequently asked questions
What lap should I use for reinforcing mesh?
Follow the structural drawings and the mesh manufacturer's data. A commonly quoted minimum for lapped fabric is around 200–300 mm (often two cross-wire spacings plus an allowance), but the governing standard (e.g. AS/NZS 4671, Eurocode 2 or ACI 318) and the specific mesh product control the required lap. This tool defaults to 200 mm; change it to match your specification.
Does this replace a reinforcement set-out drawing?
No. It is a quantity estimate to help you order sheets. The exact number depends on how sheets are laid out, staggered and trimmed. Always work to the engineer's reinforcement drawing for placement, laps and grade, and have the design verified by a competent engineer.
Why does it round up to a whole sheet?
Mesh is bought as complete sheets, not by the square metre, so a fractional requirement always rounds up. That is why 7.52 sheets becomes 8, and why adding a wastage percentage for cutting is sensible.
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