TryBuildCalcSlab Shuttering CalculatorSlab soffit and edge formwork estimator
Calculate shuttering contact area, sheets, and cost for slabs, beams, columns, footings, and walls.
🕒 Last updated: August 10, 2026
Inputs
Shuttering Mode
Slab Dimensions
Quantity & Wastage
ℹ️How many identical slabs/beams/columns/footings/walls.
Shuttering Sheet Size
ℹ️Standard shuttering plywood is commonly 2.44m x 1.22m — adjust to your supplier's sheet.
Cost
This slab shuttering job needs approximately 21.00 m² (226 sq ft) of contact area — about 8 standard sheets.
Mode
Slab
1 element
Contact Area (per element)
20.00 m²
215 sq ft
Total Contact Area
21.00 m²
226 sq ft, incl. 5% wastage
Standard Sheets
8
2.44 × 1.22 m each
Slab Breakdown
Soffit Area: 20.00 m² (215 sq ft)
Edge strip not included in this estimate.
Totals
Total Before Wastage: 20.00 m² (215 sq ft)
Extra From Wastage: 1.00 m² (11 sq ft)
Assumptions Used
Sheet size: 2.44 × 1.22 m | Wastage: 5%
Need the step-by-step erection sequence for this element? Slab Shuttering Process Guide →
Not sure how long to leave this formwork in place before striking? Formwork Striking Time Guide →
Applying release agent before the pour? Shuttering Oil / Release Agent Guide →
Slab Shuttering (Soffit View)
Looking for the verification checklist, reference tables, tips, or common mistakes?See the complete Shuttering / Formwork Calculator.
Slab soffit and edge shuttering estimate
This page pre-selects Slab mode: contact area is primarily the soffit (underside) — length × width — plus an optional edge strip (perimeter × thickness) for any exposed slab edge not already contained by a beam or wall.
It's the same slab-mode engine behind the main Shuttering / Formwork Calculator, just landing you directly on the slab inputs instead of the mode picker.
- Soffit area = Length × Width, the horizontal surface the wet concrete rests on.
- Turn on edge shuttering only where the slab edge is actually exposed — a balcony, landing, or cantilever edge.
- Enter your own slab dimensions above to replace the pre-filled 5 m × 4 m example.
How Is Shuttering Calculated?
Every mode follows the same overall sequence — calculate the contact area for one element, multiply by element count, add wastage, then convert to sheets and cost — but the contact-area formula itself differs by element type.
Step 1 — Contact Area per Element (by Mode)
Slab = (Length × Width) + optional Edge (Perimeter × Thickness)
Beam = (2 × Depth + Width) × Length
Column (rectangular) = 2 × (Length + Width) × Height
Column (circular) = π × Diameter × Height
Footing = 2 × (Length + Width) × Depth
Wall = Length × Height × (1 or 2, single/double-sided)
Slab and beam shuttering include a horizontal soffit face since the concrete rests on top of the formwork there; column, footing, and wall shuttering are perimeter-based since those elements are formed entirely from vertical side faces.
Step 2 — Apply Element Count
Total Contact Area (m²) = Contact Area per Element × Number of Elements
Use the element count for repeated identical slabs, beams, columns, footings, or wall sections in the same job.
Step 3 — Add Wastage
Final Area (m²) = Total Contact Area × (1 + Wastage % ÷ 100)
Wastage covers off-cuts at irregular edges and panel joints that don't align with standard sheet dimensions.
Step 4 — Calculate Sheet Count
Sheet Count = ROUND UP(Final Area ÷ (Sheet Length × Sheet Width))
Sheet count is the total number of standard-size panels needed to cover the final area, before accounting for reuse.
Step 5 — Calculate Cost (Optional)
Rate per m² method: Cost = Final Area (m²) × Price per m²
Rate per sq ft method: Cost = Final Area (sq ft) × Price per sq ft
Sheet method: Net Sheets to Buy = ROUND UP(Sheet Count ÷ Number of Reuses); Cost = Net Sheets to Buy × Price per Sheet
The two rate methods reflect how contractors typically bill shuttering — a rate per m² is common internationally, while a rate per sq ft is the more common convention in Indian shuttering/formwork contracts — both already factor in the contractor's own reuse and labour. The sheet method instead estimates how many physical panels you need to purchase if reusing the same panels across multiple pours.
Worked Example
This example uses the active calculator mode and inputs above and follows the same five steps from the formula section.
Input Values Used
| Input | Value | Why it is used |
|---|---|---|
| Mode | slab | Determines the contact-area geometry used |
| Element count | 1 | Multiplies the per-element area |
| Wastage | 5% | Adds allowance before rounding to sheet count |
| Sheet size | 2.44 m (8.01 ft) × 1.22 m (4.00 ft) | Converts area into a sheet count |
Step 1 — Contact Area per Element
| Calculation | Formula / Substitution | Result |
|---|---|---|
| Soffit area | 5.00 × 4.00 | 20.00 m² (215 sq ft) |
| Contact area per element | Sum of the above | 20.00 m² (215 sq ft) |
Step 2 — Total Contact Area
| Calculation | Formula / Substitution | Result |
|---|---|---|
| Total contact area | 20.00 × 1 | 20.00 m² (215 sq ft) |
Step 3 — Wastage
| Calculation | Formula / Substitution | Result |
|---|---|---|
| Final area with wastage | 20.00 × (1 + 5 ÷ 100) | 21.00 m² (226 sq ft) |
Step 4 — Sheet Count
| Calculation | Formula / Substitution | Result |
|---|---|---|
| Sheet count | ROUND UP(21.00 ÷ 2.98) | 8 sheets |
Therefore, for 1 slab element you need 21.00 m² (226 sq ft) of shuttering — about 8 standard sheets.
Disclaimer: This calculator provides approximate results for planning and estimation purposes only. Actual requirements may vary based on site conditions, materials, workmanship, and local building regulations. Always consult a qualified engineer, architect, or construction professional before making final decisions.