Measuring expanded metal might seem tricky at first, with all those terms like LWD, SWD, and strand width floating around. Because different sizes of expanded metal change with pattern and thickness, knowing how to measure all the dimensions correctly is critical for a perfect fit and performance.
Once you understand how expanded metal is made, the next step is to learn a few simple but essential measurement terms. These basics make it easier to identify the right size and help you choose expanded metal confidently for your application. Let’s go!
Key Dimensions for Measuring Expanded Metal Sizing
When you choose expanded metal, the numbers and terms on a specification sheet can look confusing at first glance: LWD, SWD, STK, SWDT, LWO, SWO, open area. So, what do they all mean? These dimensions define how the sheet performs in different applications, whether you need it to support weight, allow airflow, or provide a decorative finish. Let’s look at what each one means in simple, practical terms.
LWD (Long Way of Diamond/Longway Pitch)
LWD stands for “long way of the diamond,” and it represents the longer diagonal across each mesh opening. It’s measured from the center of one bond (also called a node or knuckle) to the center of the next along the mesh’s long direction. This value defines the main axis of the diamond shape.
A larger LWD means the openings are longer and the overall mesh is more open, which allows greater airflow, drainage, or visibility, ideal for ventilation screens or decorative panels. On the other hand, a smaller LWD produces a tighter and stronger mesh that can carry more load, making it suitable for structural applications.
SWD (Short Way of Diamond/Shortway Pitch)
SWD means “short way of the diamond,” and it refers to the shorter diagonal across each diamond opening. It’s measured from the center of one bond to the next along the short direction of the mesh. SWD, together with LWD, defines the shape and pattern of the mesh.
A small SWD creates a tighter mesh that offers greater flexibility and finer screening, perfect for plaster base, filters, or soundproofing panels. A larger SWD gives a more open structure, making the sheet lighter and improving visibility.
STK (Strand Thickness/Gauge)
STK refers to the thickness of the original metal sheet before it’s expanded. It is sometimes called “sheet thickness” or “expanded metal gauge.” This measurement plays a big role in the overall strength and durability of the finished mesh.
A thicker STK provides more rigidity and load-bearing strength, which is why it’s used for heavy-duty flooring, platforms, or security applications. Thinner material, on the other hand, is lighter, easier to cut or form, and suitable for architectural panels or interior designs.
It’s important to note that when the raised expanded metal is later flattened, its final thickness becomes slightly reduced, usually by about 10–20%, because the cold-rolling process compresses the strands.
SWDT (Strand Width)
Strand width, often abbreviated as SWDT, measures how wide each metal strip is between the openings. You can think of this as the width of the “frame” that forms each diamond. The strand width directly affects the sheet’s strength and openness.
Wider strands produce a tougher and more rigid mesh, but they reduce the percentage of open area and make the sheet heavier. Narrower strands create a lighter mesh with greater visibility and airflow, but with less structural strength.
This measurement is taken in the plane of the sheet and is different from strand thickness, which refers to the material’s depth.
LWO (Long Way Opening)
LWO means “long way of opening,” and it measures the actual clear space between the inner edges of the strands along the long diagonal. It tells you how large the opening really is, not counting the metal strand itself. This value is slightly smaller than LWD because LWD includes the strand width on both sides of the opening.
LWO is especially important for applications that require precise control of air, water, or particle flow, such as filtration screens, speaker grilles, or protective guards. If the sheet is flattened, the same dimension is sometimes referred to as the Longway Aperture (LWA), and it’s measured horizontally from internal edge to edge.
SWO (Short Way Opening)
SWO means “short way of opening,” which is the open distance between the inner edges of the strands along the short diagonal of each diamond. Like LWO, SWO tells you the true gap size but in the shorter direction. The SWO value is crucial for fine filtration, acoustic control, and applications that require limited visibility or higher security.
In a flattened mesh, this is also called the Shortway Aperture (SWA). SWO is always smaller than SWD because SWD measures from center-to-center, while SWO measures only the clear opening.
Open Area Percentage
Open area percentage indicates how much of the sheet surface is open space compared to the total area. It’s calculated using the LWD, SWD, strand width, and strand thickness. For instance, if a mesh has 70% open area, it means 70% of the surface is open holes while 30% is solid metal. This figure helps you understand how easily air, light, or liquid can pass through the mesh.
A high open area, usually between 70% and 90%, is ideal for ventilation panels, grilles, and decorative screens. A lower open area, typically below 30%, produces a stronger and more secure sheet suitable for heavy-duty or safety applications. Choosing the right balance between open area and strand size is key: more openness improves flow and visibility, but too much can reduce the mesh’s strength.
How to Measure Expanded Metal of Different Designs
When selecting or specifying expanded metal, it’s essential to know whether the mesh is either Raised (Standard) or Flattened, because these two common designs are measured differently for their structure. Raised mesh uses center-to-center “pitch” dimensions, while flattened mesh focuses on inner-edge “aperture” openings. Let’s see more details:
Raised Expanded Metal
Raised expanded metal, also known as standard, regular, or unflattened mesh, is the original form produced directly after the slit-and-stretch process. It has a three-dimensional, louvered surface where the strands and bonds are angled, giving the sheet extra rigidity and traction.
When measuring raised expanded metal, the key dimensions are based on the pitch, meaning measurements are taken from the center of one bond (node) to the center of the next. The Longway Pitch (LWP) is measured horizontally along the length of the diamond, while the Shortway Pitch (SWP) is measured vertically across the short axis. These two dimensions define the overall diamond pattern.
The strand thickness (STK) is the thickness of the original metal sheet before expansion, which remains unchanged through the process, and the strand width (SWDT) is how much material is left between the slits.
Since the mesh is three-dimensional, its height must also be considered when calculating total thickness. The open area percentage is then determined based on the LWD, SWD, strand width, and strand thickness, revealing how much of the sheet surface is open space for airflow or visibility.
Flattened Expanded Metal
Flattened expanded metal is produced by cold-rolling standard mesh through flattening rolls to create a smooth, level surface. This secondary process compresses the angular strands into a single plane, giving the sheet a uniform thickness and a clean appearance. As we mentioned earlier, the flattening process slightly reduces the material’s overall thickness, usually by 10 to 20 percent compared to its raised form.
When measuring flattened expanded metal, the focus shifts to the aperture or opening dimensions. The Longway Opening (LWO), sometimes called the Longway Aperture (LWA), is the horizontal clear distance measured from the inner edge of one strand to the inner edge of the next along the long axis. The Shortway Opening (SWO), or Shortway Aperture (SWA), is the vertical clear gap measured in the same way along the short axis. These values represent the true open spaces through which air, light, or particles can pass.
The strand thickness (STK) is taken after flattening and reflects the slight reduction in material thickness, while the strand width (SWDT) continues to define the width of the metal strips between openings. As with raised mesh, the open area percentage is calculated using the openings, strand width, and thickness to describe the ratio of open to solid metal.
Example: 4×8 Expanded Metal Sheet
The 4×8 expanded metal sheet (about 1220 x 2440 mm) is used here as an example for demonstrating the specification we introduced above because it’s the industry standard size, widely stocked, easy to handle, and compatible with most fabrication setups. This sheet size represents a practical reference point for comparing different mesh patterns, thicknesses, and open areas.
Among the many available types, the 3/4″ #9 mesh is one of the most common for industrial and architectural applications. Note that the 3/4 inch refers to the nominal long way of the diamond (LWD), which is the longer diagonal of each diamond-shaped opening. It doesn’t mean the actual opening is exactly 3/4″, because the strand width takes up some space. Also, the #9 refers to the gauge number, which is a traditional way of describing the thickness of the metal before it’s expanded.
For raised expanded metal:
| Dimension | Description | Typical Value | Measurement Note |
| LWD (Long Way of Diamond) | Distance from the center of one bond to the next along the long axis | 1.333″ | Measured center-to-center along the long way (includes strand width) |
| SWD (Short Way of Diamond) | Distance from the center of one bond to the next along the short axis | 0.577″ | Measured center-to-center across the short way |
| LWO (Long Way Opening) | Clear open space between inner strand edges along the long way | 1.000″ | Measured edge-to-edge, not including metal |
| SWO (Short Way Opening) | Clear open space between strand edges across the short way | 0.500″ | Actual free opening |
| SWDT (Strand Width) | Width of the metal strand between openings | 0.164″ | Affects strength and open area |
| STK (Strand Thickness) | Thickness of base metal before expansion | 0.119″ | #9 gauge sheet metal |
| Overall Thickness (Height) | Height of raised mesh from peak to valley | 0.30–0.35″ | Due to its 3D raised form |
| Open Area (%) | Percentage of open space | ≈69% | Typical for standard raised 3/4″ #9 mesh |
For flattened expanded metal:
| Dimension | Description | Typical Value | Measurement Note |
| LWD (Long Way of Diamond) | Original pitch, center-to-center along the long way | 1.333″ | Remains the same as raised mesh (pitch) |
| SWD (Short Way of Diamond) | Original pitch, center-to-center across the short way | 0.577″ | Remains the same as raised mesh (pitch) |
| LWO (Long Way Opening) | Clear gap after flattening (horizontal measurement) | 2.10″ | Increases slightly after flattening |
| SWO (Short Way Opening) | Clear gap after flattening (vertical measurement) | 0.923″ | Also widens slightly after flattening |
| SWDT (Strand Width) | Width of flattened strand | 0.164″ | Same as before flattening |
| STK (Strand Thickness) | Reduced thickness after rolling | ≈0.10–0.12″ | About 10–20% thinner than raised |
| Overall Thickness (Height) | Flattened height (sheet thickness) | ≈0.12″ | Smooth, flat surface—no raised ridges |
| Open Area (%) | Percentage of open space | ≈70–71% | Slightly higher due to stretching during flattening |
How to Determine the Correct Expanded Metal Size
Determining the correct size and type of expanded metal for your project means finding the right balance between strength, weight, conductivity, and openness. Let’s look at some important factors you should take into consideration.
Mesh Pattern and Openness
First, pay attention to the size of the diamond openings and the metal strands that form them, as they directly impact how much air, light, or liquid can pass through.
If your project requires maximum airflow or visibility, such as for ventilation panels, speaker grilles, or security screens, opt for a high open area percentage, typically 80% or higher. Larger openings, combined with thinner strands, increase both LWO and SWO, resulting in greater transparency and flow.
In contrast, for filtration or screening, where particles must be blocked above a certain size, you need to specify the exact aperture dimensions: SWO and LWO. These tell you the true, clear space a particle can pass through.
A smaller SWD creates a tighter mesh with finer filtration performance. For structural or aesthetic purposes, the geometry also matters: when LWD is closer in size to SWD, the mesh appears more square and compact, offering extra strength and a more uniform appearance.
Strength and Load-Bearing Capacity
Strength and rigidity depend mainly on the amount of metal in the pattern, which is controlled by strand width and thickness. For heavy-duty applications such as platforms, guards, or frames, choose wider strands and thicker metal. A wider strand width (SWDT) means more material in each bond, giving the sheet higher strength and stiffness but reducing the open area.
Similarly, a lower gauge number (thicker base metal) increases load capacity and durability. A denser pattern, with smaller openings (lower SWD and LWD), packs more metal into each area, making the mesh tough enough to support loads while still allowing drainage or ventilation.
Materials and Weight
The next step is to select the right material and thickness for your application’s environment and performance needs. For lightweight designs, such as aerospace or transport components, thin-gauge expanded metal foils made from aluminum or titanium offer strength with minimal weight. Expanded metal is already lighter than solid sheet metal thanks to its open structure, and a well-balanced pattern can achieve an excellent weight-to-strength ratio.
For corrosion resistance, choose materials like stainless steel or aluminum, both of which handle moisture and chemicals well. Aluminum can also be anodized, while coatings like galvanizing, polyester powder coating, or painting add extra protection and aesthetic appeal.
Finally, for quality assurance, it’s important to source from manufacturers that follow recognized standards such as EMMA 557-20 or ASTM F-1267-18 (2023). One simple way to verify compliance is by weighing the sheet and comparing it with published standard weights, which confirm that the strand width and thickness are correct.
Application-Specific Requirements
Every application has its own priorities, and different projects focus on specific dimensions. Here are some common examples:
- Walkways and Platforms: Prioritize strand width, thickness, and sheet orientation. Use raised expanded metal for traction; orient the diamonds left-to-right underfoot for the best grip.
- Security Fencing: Emphasize orientation, SWD, and strand width. Mounting the mesh with the long way of the diamond pointing vertically makes climbing difficult. Choose thicker metal and wider strands for security strength.
- EMI/RFI Shielding: Use conductive materials such as copper or aluminum foils. Specify micro expanded metal with very fine SWO/LWO openings to block high-frequency waves effectively.
- Current Collection and Conductive Layers: Opt for lightweight, highly conductive materials like copper or aluminum, maintaining a high open area to reduce resistance while keeping enough rigidity for handling.
KEN GI is Your Reliable Supplier for Different Sizes of Expanded Metal
Understanding how to measure expanded metal sheet’s specifications helps you choose the right one for your project, whether you need more strength, airflow, or a lighter structure. Once you know the difference between raised and flattened mesh and how each dimension affects performance, the next step is finding a supplier you can trust to deliver precision and quality.
With over 40 years of manufacturing expertise, KEN GI has become a leading name in manufacturing expanded metal and related machinery. We specialize in producing expanded metal, tailored to meet the needs of construction, industrial, and architectural projects.
Finished Dimensions of KEN GI’s Expanded Metal
To help you choose the right expanded metal size, here is how we define the finished dimensions in simple terms:
SWD (Short Way of Diamond): This is the finished length measured along the short direction of the diamond openings. The length in the SWD direction is generally flexible and can be cut to match your needs. The maximum finished size in the SWD direction is roughly 6.2 inches (160mm).
LWD (Long Way of Diamond): This is the finished width measured along the long direction of the diamond openings. The maximum sheet width in the LWD direction is 8 ft.
Not sure which direction or size works best for your application? Share your usage or drawing with us, and we will help confirm the most suitable finished dimensions for you.
Our complete service process covers everything from material selection and design customization to production, inspection, and reliable delivery, backed by responsive after-sales support. From standard mesh and rib lath to diamond plate sheets and custom patterns, every KEN GI product is engineered for performance, consistency, and long-term durability. Whether you’re sourcing for large-scale construction or precision industrial components, we deliver products that combine strength, functionality, and value.
Ready to specify or customize your expanded metal? Contact us today to discuss your project needs and discover how our expertise can bring your ideas to life.