Project A: first row at 2.8 metres
A corporate exhibition room, 4.8 by 2.7 m. One quote specified P2.5, another P1.86 at 30 percent more.The room is 11 m long and the first row sits 2.8 m from the screen. At that distance, P2.5 shows visible pixel structure on white text and thin lines. The client paid the premium and the complaint stopped being about legibility.
Project B: nobody closer than 8 metres
An atrium wall mounted seven metres up, viewed from the floor. P2.5, with the savings spent on a backup player and a spare power supply.Nine months of daily use, no complaints. The nearest viewer is more than twice the distance at which the pitch becomes visible, so the extra density would have been invisible and unrecoverable.
The rule that separated them
Closest comfortable viewing distance is roughly pixel pitch in millimetres times 2.5 to 3. P2.5 gives 6.2 to 7.5 m; P1.86 gives 4.6 to 5.6 m.Below that distance you see structure. Above it you are paying for pixels nobody resolves.
What the price actually buys
P1.86 has about 289,000 pixels per square metre against 160,000 for P2.5. On the 13 square metre wall that is roughly 1390 x 780 against 1030 x 580.The premium buys eighty percent more LEDs, more driver ICs, denser PCB and lower yield. A 30 percent premium is normal. Below 20 percent, ask about LED brand, driver IC and binning.
Two specs that get skipped
Refresh rate at 3,840 Hz or above, or phone cameras will show scan lines during meetings and live streams.Average power around 280 W per square metre at P1.86, which means the 13 square metre wall needs about 3.6 kW and a 5 kW supply with air conditioning. Old buildings run out of power before they run out of wall.