📏 Lỗ Ban Ruler
The carpenter's feng-shui ruler on your screen: type or drag any measurement and see where it lands on all three Lỗ Ban scales at once. The 52.2 cm scale is for door openings, 42.9 cm for furniture and solid blocks, 38.8 cm for altars and grave work. Each zone is named, judged lucky or unlucky, with the nearest lucky range suggested.
👆 Drag on the ruler to slide the red line — or type the number. Each band shows one full cycle of that scale; the measurement wraps around it.
📖 How the three scales are used
For the CLEAR opening where air and light pass: door and window openings measured inside the frame. 8 zones × 65.25 mm.
For SOLID built things of the living: furniture, beds, kitchen counters, steps, sills — measured over the solid block. 8 zones × 53.625 mm, each with 4 named sub-zones.
For what belongs to the ancestors: altars, ancestral tablets, graves and tombs. 10 zones × 38.8 mm.
📏 The Lỗ Ban ruler is carpentry folklore named after the legendary Chinese master builder — a tradition of auspicious dimensions, not physics. Build to code first; let the lucky millimetres come second.