How big is the compass for beginners to learn Feng Shui?

Compasses are round and square, big and small. First of all, we should choose a square one, which is conducive to being parallel to the door and convenient for measurement. We should choose a slightly larger one, because each of the 24 mountains is 15 degrees. The larger the compass, the smaller the error and the higher the measurement accuracy.

Compass plays the role of compass, the pointer is magnetic, and metal has a great influence on it. Try not to choose metal compass.