Expanded Metal Weight Calculator
Calculate weight per m², open area %, and total sheet weight for standard and flattened expanded metal.
Open area
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Weight per m²
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Sheet weight
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How the calculation works
Expanded metal weight per square meter is calculated in two steps:
OA% = (LWD × SWD) / ((LWD + SW) × (SWD + SW)) × 100
W (kg/m²) = t × ρ × (1 − OA/100) × 10
Where LWD = long way diamond opening (mm), SWD = short way diamond opening (mm), SW = strand width (mm), t = sheet thickness (mm), ρ = material density (g/cm³). For a standard 50×25mm pattern with 3mm strand width and 1.5mm steel sheet, open area ≈ 45.2% and weight ≈ 6.49 kg/m².
Theoretical value only. Actual weight varies ±5% with manufacturing tolerances, strand geometry variation, and surface treatment (hot-dip galvanizing adds approximately 3–5% weight). Always confirm with your supplier before booking freight.
Frequently Asked Questions
How is expanded metal weight per m² calculated?
Expanded metal weight per m² is calculated as: W = t × ρ × (1 − OA/100) × 10, where t is sheet thickness in mm, ρ is material density in g/cm³, and OA% is the open area percentage. Open area is derived from the strand geometry: OA% = (LWD × SWD) / ((LWD + SW) × (SWD + SW)) × 100.
What does LWD, SWD, and SW mean for expanded metal?
LWD (Long Way Diamond) is the longer diagonal of the diamond opening. SWD (Short Way Diamond) is the shorter diagonal. SW (Strand Width) is the width of individual metal strands. These three dimensions define the mesh pattern and determine the open area percentage.
What is the difference between standard and flattened expanded metal?
Standard expanded metal has a raised, textured surface with diamond openings at an angle. Flattened expanded metal is processed through a roller after expansion to produce a flat, smooth surface. Flattened versions are heavier per m² because the thickness effectively increases from compression.
What is a typical open area for expanded metal?
Most standard expanded metal has an open area between 45% and 65%. Lighter architectural grades can reach 75–80%. Heavy-duty gratings typically have 40–55% open area. Higher open area means better drainage and ventilation but lower strength.
What materials are available for expanded metal?
Common materials include carbon steel (density 7.85 g/cm³), hot-dip galvanized steel, stainless steel 304/316 (7.9/7.98 g/cm³), and aluminum (2.7 g/cm³). Expanded metal can also be made from copper and titanium for specialized applications.
How accurate is this calculator?
This calculator uses the geometric formula based on LWD, SWD, and strand width dimensions. Results are theoretical and typically within ±5% of actual weight. Actual weight varies with manufacturing tolerances, surface coatings (galvanizing adds ~3–5%), and edge finishing.
What is the difference between SWD and SWO, LWD and LWO?
SWD/LWD (Short/Long Way Diamond) refers to the full diagonal of the opening including strand overlap. SWO/LWO (Short/Long Way Opening) is the clear opening dimension. Many manufacturers specify SWO/LWO; the calculator uses SWD/LWD. Approximately: SWD ≈ SWO + SW.
Can this calculator be used for expanded metal grating?
Yes. Heavy expanded metal grating (e.g., 5mm thick, large diamond) follows the same formula. For structural grating applications, also check the load capacity using our companion Steel Grating Weight Calculator at SteelGratingCalculator.com.
Related Resources
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