Folding rules consist of two or more rule strips which are joined with pivoting hinges.

Rules which are able to fold can be used to gauge angles. The angle can then be easily transferred to a workpiece or surface, or measured with a protractor.

Folding rules can be useful for measuring angles that would be difficult to measure directly with a protractor. They can also be used with very large objects to estimate their angles from a distance, such as roof slopes or piping angles.

Step 1 – Position rule

Line two sections of the rule up with the angle you want to measure. If you can, press the two sides into or against the angle.

If you are judging an angle further away, make sure you are looking at it straight, using two sections of the rule to gauge what the angle is.

Step 2 – Transfer or measure angle

Hold the angle you have gained from the two pieces of rule in position. The angle can be directly transferred onto a material and marked out using the rule strips as a guide, or placed against a protractor to read the angle in degrees.