For a guard to be safe, openings must be narrow enough to prevent a finger, hand, or arm from reaching far enough to be caught or severed by a moving part, such as a motor, belt, or gear.

A safe distance calculator is definitive a plus when designing and validating machine safeguards. The Securimetre is a simple tool that ensures that the dimensions of an opening in a guard comply with the safety standards in force for the machinery in question. The IRSST has developed an app that simplifies the calculation and interpretation of results according to the different standards in effect.