Lo Ban Ruler Lookup

The Lo Ban ruler is a measuring ruler used in house building and woodworking according to Eastern feng shui beliefs. The ruler is divided into a series of segments: red segments are good, black segments are bad. When designing, sizes are chosen to fall in a red segment, in the hope of bringing the family peace and prosperity.

Today 3 types of ruler are commonly used, each for its own group of measurements:

• 52.2 cm ruler (clear openings): measures the empty space that light and air pass through, such as the clear opening of the front door, room doors, windows, gates, vents and skylights.
• 42.9 cm ruler (Dương trạch, for the living): measures solid elements in the house such as kitchen counters, entrance steps, stair treads, columns, and the overall dimensions of walls, beds and cabinets.
• 38.8 cm ruler (Âm phần, for ancestors): measures altar and ceremonial furniture such as altars, altar cabinets, ancestral tablet frames, wooden daybeds and graves.

How to use the tool

1. Enter a measurement in the box above (choose cm or mm), or drag the ruler left or right. The − and + buttons change the measurement by 1 cm per click.
2. The yellow line in the middle marks the exact measurement. The results show which segment the measurement falls in, and whether it is good or bad on each type of ruler.
3. If the measurement falls in a bad segment, check the suggestion line to increase or decrease it slightly to reach the nearest good segment.

Note: doors should be measured by their clear opening (the empty space inside the frame). The Lo Ban ruler is a folk tradition, so weigh it together with practical use and your architect's advice when finalizing dimensions.