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Lintel Quantity Calculator

Enter opening width, quantity and wall thickness to get lintel length, concrete volume, formwork and a suggested depth.

Quick answer

With the default inputs: Opening width 1.2 · Number of openings 10 pcs · Wall thickness 0.24 etc.Total lintel length 17.0 m

Edit the inputs below to recalculate.
Wall thickness mLintel depth m
Lintel length = opening width + 2 × bearing, typically 250 mm each side; wall thickness sets the lintel width.

Inputs

Clear width of the opening
pcs
Enter 0 to auto-use opening / 8
Usually 250 mm; 300-370 mm for openings over 1.5 m

Result

Total lintel length
17.0m
Length per lintel1.70m
Depth used0.15m
Total concrete0.612m³
Formwork area9.2m²
Concrete per opening0.061m³

Leaving the depth at 0 derives it from opening / 8 rounded up to 50 mm, minimum 120 mm. Formwork counts two sides plus soffit (the soffit spans the opening and must be cambered). Most projects use precast lintels from a standard album; read the table instead.

Formula

Length per lintelL = opening width + 2 × bearing
Suggested depthh = opening ÷ 8 (round up to 50 mm, min 120 mm)
ConcreteV = L × wall thickness × h × quantity
FormworkA = (2 × L × h + L × wall thickness) × quantity
10 openings 1.2 m wide, 240 mm wall, 250 mm bearing, depth left at 0: depth auto 0.15 m, 1.70 m per lintel, 17 m total, 0.612 m³ concrete, 9.18 m² formwork.

How to work it out

  1. Length per lintel L = opening width + 2 × bearing length, normally 250 mm or 300 mm in seismic work.
  2. Depth from experience h = opening width ÷ 8, rounded to 50 mm and not less than 120. A 1.2 m opening gives 150 mm, a standard size.
  3. Concrete V = L × wall thickness × h × number of openings.
  4. Formwork A = (2 × L × h + L × thickness) × count — two sides plus the soffit, which unlike a ring beam is suspended and must be formed.
  5. Count openings from the schedule, grouping by size and separating by wall thickness, since both concrete and formwork depend on it.

Where it goes wrong

Material and cost

Cast-in-situ lintels run 130-190 per metre all in (concrete, steel, formwork, labour); precast 60-120 each before installation. A project with 100 openings spends 15,000-25,000 on lintels.

On site

Basis

FAQ

Why must a lintel bear into the wall, and how far?
The lintel must transfer load into the masonry either side, not merely span the gap. 250 mm per end is standard; 300-370 mm for openings over 1.5 m; more in seismic zones or where the wall end is close to the opening. Too short a bearing crushes the wall end — a very common defect.
Precast or cast-in-situ lintels?
Precast is fast, formwork-free and consistent — ideal for standard openings in volume, chosen straight from the album. Cast-in-situ gives better integrity and handles non-standard sizes, heavy loads or monolithic casting with ring beams, at the cost of formwork and curing time.
Must the depth always be opening / 8?
1/8 is a starting rule of thumb; the code requirement is a real bending and shear check against the actual wall load above. Large openings, tall walls above, or concentrated loads (padstones, canopies) must be checked rather than proportioned. Seismic zones add minimum reinforcement ratios and stirrup densifying.

Cite this page

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

Building Calculator. Lintel Quantity Calculator. 2026-10-25. https://jianzhujisuan.com/en/lintel-schedule

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.