# Formwork Plywood Calculator

Plywood sheet count from area, sheet size and reuse cycles.

- Page: https://jianzhujisuan.com/en/formwork-plywood
- Category: Construction (https://jianzhujisuan.com/en/c/construction)
- Chinese version: https://jianzhujisuan.com/zh/formwork-plywood.md
- Data checked: 2026-10-25

## Quick result

With the default inputs (Formwork area 500 m², Sheet size 1220×2440 mm (standard), Waste 8%, Reuse cycles 3 cycles): **Plywood sheets 61 sheets**

## Inputs

| Parameter | Type | Default | Unit | Note |
|---|---|---|---|---|
| Formwork area | number | 500 | m² |  |
| Sheet size | select | 1220×2440 mm (standard) | — |  |
| Waste | number | 8 | % |  |
| Reuse cycles | number | 3 | cycles | Times the form can be reused, usually 3-6 |

## Formula

- **Area per sheet**: Asheet = W×L (1220×2440 = 2.977 m²)
- **Sheets**: N = ⌈area×(1+waste%) ÷ reuse⌉

## Worked example

500 m², standard 1220×2440, 8% waste, 3 cycles: 2.977 m² per sheet, 540 m² with waste, ~180 m² after reuse, about 61 sheets.

### Sheet count by area and reuse cycles (1220×2440, 8% waste, same formula as this page)

| Formwork area (m²) | 1 cycle | 2 cycles | 3 cycles | 5 cycles | Area per sheet (m²) |
|---|---|---|---|---|---|
| 100 | 37 | 19 | 13 | 8 | 2.977 |
| 200 | 73 | 37 | 25 | 15 | 2.977 |
| 500 | 182 | 91 | 61 | 37 | 2.977 |
| 1000 | 363 | 182 | 121 | 73 | 2.977 |
| 2000 | 726 | 363 | 242 | 146 | 2.977 |
| 5000 | 1815 | 908 | 605 | 363 | 2.977 |

### Waste allowance by element (typical ranges, not a bill-of-quantities figure — check what your last floor actually used)

| Element | Typical waste | Where the waste comes from |
|---|---|---|
| Regular walls and large slabs | 5-8% | Only edge trimming and corners; most of the sheet is used |
| Beams, columns, many junctions | 10-15% | Lots of short pieces; one sheet will not cover many faces |
| Curved, circular and irregular shapes | 15-25% | Whatever is left after the curve is scrap |
| Second-fix work and small patches | 15-20% | Sheets are bought whole even when a small piece is needed |
| Fair-faced concrete | 10-15% | Joint and tie-hole positions are critical, so offcuts cannot be used up |

### Panel type against reuse cycles (typical values, not code limits — reuse depends on curing, release agent and stripping time)

| Panel type | Typical thickness (mm) | Typical reuses | Off-form finish | Best for |
|---|---|---|---|---|
| Plain plywood (poplar core) | 12-15 | 3-4 | Fair, needs sanding | Footings, basements, concealed work |
| Phenolic film-faced | 15-18 | 6-8 | Good, clean release | Shear walls, beams and slabs |
| High-density film-faced (imported face) | 18-21 | 8-12 | Excellent, near fair-faced | Fair-faced concrete, exposed walls |
| Bamboo plywood | 12-15 | 8-10 | Good, wear resistant | Typical floors, heavily reused areas |
| Steel frame with timber face | 18 | 15-20 (face replaced) | Excellent | High-rise typical floors, aluminium formwork substitute |


## Questions

### How do I set the reuse cycles?

By panel type and concrete finish. Ordinary timber 3-6 times, film-faced 6-8, aluminium and steel dozens to hundreds; fair-faced concrete needs fresh panels, 1-2 uses. Reuse directly sets the take-off - six cycles uses half the panels of three - but only if panels are struck on time, cleaned and oiled, and handled gently; rough striking wrecks a panel in one go.

### Why use developed area instead of floor area?

Because formwork touches the concrete surface: walls count two faces, columns four, beams three sides plus soffit, slabs the underside. Developed area is these faces laid flat, usually 2-4× the floor area. Estimating by floor area under-counts badly, so formwork is always measured by developed (contact) area.
### How many square metres in a 1220×2440 plywood sheet?

1.22 × 2.44 = 2.977 m². The small 915×1830 sheet is 1.674 m². Divide the area by that and always round up — offcuts cannot be joined into a panel.

### How many sheets for 500 m² of formwork?

182 sheets at one use, 91 at two, 61 at three. That is the one-off purchase: more reuses mean fewer sheets in hand at once, but stripping and curing have to be scheduled to allow it.

### Is more reuse always cheaper?

On amortisation yes, but not linearly. Plain plywood is good for about three uses; after that the edges fur up and joints leak grout, and the patching and sanding cost overtakes the saving. Fair-faced work often changes panels after one or two uses.

### How is formwork area calculated for beams and columns?

Developed area, not plan area: beams take both sides plus the soffit (the slab soffit is not counted twice), columns take the perimeter times height, and junctions with slabs and walls are deducted. Sketch the developed shape before entering numbers.


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Generated by BuildCalc. All calculations run in your browser; no data is uploaded. Formulas follow national standards and common trade practice; local codes govern.