what is the standard accuracy of spirit level ?

The accuracy of the general spirit level is related to various factors. The accuracy is not that the longer the spirit level is, the more accurate is. The accuracy also depends on the straightness of the material, the quality of the level bubble, the wall thickness of the ruler, and whether the base bottom surface has been milled.

The accuracy classification of the spirit level is expressed in numerical values, and the unit is mm/m. For example, a level with an accuracy of 0.75mm/m means that the error per meter of the level is not more than 0.75mm. The accuracy of the level is generally as follows: 0.25mm/m, the angle is expressed as 0.0143°, 0.5mm/m, the angle is expressed as 0.0286°, 0.75mm/m, the angle is expressed as 0.0430°, 1mm/m, the angle is expressed as 0.0573°, 1.5mm/m, the angle is 0.0859°, 2mm/m, the angle is 0.1146°.

Jinhua Haode Technology Co.,ltd have full equipments to check and control the accuracy.
First, the bubbles are made by our factory, there are more than 10pcs digital machines to make 24 hours every day.
Second, the material of bubble guard is raw acrylic with high sensitive and transparent color
Third, the bubbles will be tested and check accuracy before assembled to the spirit levels
Forth, all the professional spirit levels will be tested by computer machine which can enlarge the bubble and show the exact accuracy on the screen
Fifth, Jinhua Haode Technology Co.,ltd have so many workers with many years experienced.

For high quality spirit levels, the accuracy can be promised within 0.5mm/m, and the normal quality is 1.0mm/m.