算BuildCalc

Formwork Area Calculator

Pick a member type, enter section and length, and get the formwork contact area plus sheet and batten estimates.

Quick answer

With the default inputs: Member type Rectangular column · Section length 0.5 · Section width 0.5 etc.Formwork area 6.00 m²

Edit the inputs below to recalculate.
Length LWidth W
Section length and width give the perimeter; multiply by member height for the contact area — not the concrete volume.

Inputs

Column height, beam depth or wall height; not used for slabs
pcs
cycles
Plywood 3-5, steel formwork 20+

Result

Formwork area
6.00m²
MemberColumn
Contact area6.00m²
Sheet area2.98m²
Sheets (no reuse)3sheets
Sheets per set at 3 cycles1sheets
Timber battens2.1m
Tie rods7bars

Formwork assumes 1220×2440 mm plywood. Reuse cycles depend on member type and striking strength.

Formula

ColumnA = 2 × (a + b) × height × qty
BeamA = (width + 2 × depth) × length × qty
SlabA = length × width × qty
WallA = 2 × length × height × qty
Sheetssheets = A ÷ 2.98 (1220×2440 per sheet)
One 500 × 500 mm column 3 m tall: 2 × (0.5 + 0.5) = 2 m perimeter, 6.00 m² of contact area, about 3 sheets of plywood — one sheet per set over three reuses. Ten columns give 60 m² and seven sheets per set.

How to work it out

  1. Formwork is measured on contact area between concrete and form — not the surface area of the element and not floor area.
  2. Columns: perimeter × height, deducting the beam and slab intersection where no form is fixed.
  3. Beams: soffit (width × clear span) plus two sides (2 × net depth below slab × clear span); the depth within the slab is not formed.
  4. Slabs: soffit on net area less columns and beams, plus edge form as slab depth × perimeter.
  5. Walls: both faces less openings, plus reveals.

Where it goes wrong

Material and cost

An all-in formwork rate runs about 45-70 per m² of contact area including labour, material and supports, excluding height extras, with labour at 55-65%. Turnover drives the cost: timber formwork gives 5-8 uses, aluminium gives over 200 but needs about 1,200 per m² up front — only worth it with many repetitive floors.

On site

Basis

FAQ

Why measure contact area rather than concrete volume?
Formwork is measured, priced and bought by contact area, and there is no fixed ratio to concrete volume. One cubic metre in a massive footing needs almost none, while the same volume in a thin wall needs 8-10 m². Each member must be calculated separately.
Should slab thickness be deducted from beam formwork?
Yes. The side form only runs from the slab soffit down, so its height is beam depth minus slab thickness, and column formwork is reduced by the beam depth at connections. This tool uses the full beam depth, so the result runs slightly high and should be adjusted when cutting.
How do reuse cycles affect cost?
Formwork cost is amortised over reuses: a 100 m² set used three times spreads its price over 300 m², so the rate per square metre is a third of the purchase price. Plywood typically manages 3-5 cycles with edge trimming and release agent, while steel forms reach 20 or more at a higher upfront cost.

Cite this page

Use this format in reports, method statements or coursework. The link is permanent.

Building Calculator. Formwork Area Calculator. 2026-10-25. https://jianzhujisuan.com/en/formwork-area

Results are estimating aids only and are not a design basis. Construction and final accounts must follow the drawings, the applicable standards and an approved method statement. Anything affecting structural safety, shoring or falsework must be checked by a suitably qualified engineer.