The three numbers most often confused in an LED project are metres, cabinet quantity and pixels. They must be linked through the actual cabinet size and pixel pitch. With a 640 × 640 mm cabinet, convert millimetres to metres first, calculate the physical screen from cabinet columns and rows, and then calculate resolution from the pixel count of one cabinet.
If the cabinet is 640 mm wide and 640 mm high, a layout with N columns and M rows has an external cabinet size of 0.64N metres × 0.64M metres. If the product is P2.5, one cabinet is approximately 640 ÷ 2.5 = 256 pixels in each direction, so the theoretical resolution is 256N × 256M. For P5, the same physical cabinet would be approximately 128 × 128 pixels. This calculation is valid only when the actual cabinet dimensions, pitch and active pixel area match the assumed values. The cabinet drawing and receiving-card configuration remain the final references.
For example, a 3.2 × 1.92 m centre screen can be built from five columns and three rows of 640 mm cabinets. At P2.5, the estimated resolution is 1,280 × 768 pixels. Each 1.92 × 1.92 m side screen can be built from three columns and three rows, giving an estimated 768 × 768 pixels. The processor may control all three screens, but the three areas remain independent mechanical and logical zones. Their pixels should not be combined into one rectangle when planning structure, maintenance or content coordinates.
If the customer says “about three metres” or provides a width that cannot be achieved with whole cabinets, do not round it silently. Show whether the difference will be a frame, a gap, a non-standard cabinet, a changed target size or an installation tolerance. “We can trim it on site” or “the software can scale it” should be treated as a design change because it may affect structure, aspect ratio, processor loading and content production.
After calculating resolution, perform three checks. First, confirm that the processor and sending equipment can handle the total pixel load, output dimensions and each port branch. Second, confirm that the receiving-card configuration matches the cabinet, module scan mode, data group and cascade direction. Third, confirm that the content source can fill each screen area without unwanted stretching. Correct arithmetic does not guarantee a working display; signal quality, configuration, refresh, power and temperature still matter.
The best handover document is a cabinet-to-pixel schedule. It should show cabinet columns, cabinet rows, total cabinets, physical size, cabinet resolution, screen resolution, output port and content window for each independent screen. Every number should be traceable to a cabinet drawing, nameplate or approved specification so that sales, engineering, installation and after-sales teams use the same data.
Add a tolerance note to the schedule. A nominal 3.2 m screen may be exact when built from five 640 mm cabinets, but the finished opening, frame, trim and structural clearance can be different. State whether the dimension refers to the LED face, the complete cabinet assembly, the opening or the installation area. This distinction is especially important when the screen sits inside a wall or when the customer has specified a finished architectural opening.
The resolution schedule should also show what happens at the controller. A screen can have a correct theoretical resolution but still be divided across several output ports, processors or independent windows. Mark the start cabinet, cascade direction, port number and screen-zone coordinate. For a three-screen system, keep CENTER, LEFT and RIGHT as separate names even if one processor uses a single large input canvas. This makes content production, remote diagnosis and future replacement much easier.
When a cabinet is not exactly 640 × 640 mm, or when the active display area is smaller than the mechanical cabinet, use the factory value rather than the simplified formula. The same applies to fine-pitch modules whose actual active pixel count has a special definition. A good rule is: use calculation for planning, use the product drawing for ordering, and use the receiving-card file plus a test pattern for commissioning. If those three references disagree, stop and resolve the discrepancy before the screen is assembled.
Frequently Asked Questions
Q1: Is a 640 × 640 mm P2.5 cabinet always 256 × 256 pixels?
Only when the actual pitch and active display area match that calculation. Check the module drawing, real pitch and manufacturer definition.
Q2: Can the three screens be combined into one ultra-wide video?
Yes, if the processor and content system support it. The mechanical layout, service boundaries and screen coordinates should still be documented separately.
Q3: Why can the physical dimensions be correct while the image is misaligned?
Cabinet direction, cascade order, receiving-card configuration, data group and port mapping may be wrong.
Q4: Should a quotation be based on area or cabinet quantity?
Technical planning should be based on cabinet quantity and actual geometry. Commercial pricing should also identify modules, cabinets, spares, structure, power, control, packaging and installation.
