Machine Guard Distance Calculator

Work out machine guard distance instantly with clear inputs, formula shown and shareable results.

About Machine Guard Distance Calculator

Safety distances for reaching through a regular opening depend on which part of the limb can pass. Slots up to 4 mm exclude even a fingertip, 8 mm admits a finger to the first knuckle needing 20 mm clearance, and above 20 mm the whole arm can reach so 850 mm is required. Reaching over a guard is treated separately and depends on guard height.

Formulas

Reach through

Safety distance rises in steps with opening size: 2 mm at 4 mm opening, 20 mm at 8 mm, 120 mm at 20 mm, 850 mm above 30 mm

Reach over

A 1400 mm guard needs about 900 mm horizontal distance; 1800 mm needs only 100 mm

Worked example

With the default values below, Machine Guard Distance Calculator returns Safety distance required through the opening of 120. Change any input above and every figure here is recalculated in your browser.

Inputs used

Opening size in the guardaccepts 1–200 mm: 20 mm
Guard heightminimum 100 mm: 1,400 mm
Hazard height above the floorminimum 0 mm: 1,000 mm

Results

Safety distance required through the opening: 120 mm
Limb that can pass the opening: Hand up to the knuckle joint
Safety distance for reaching over the guard: 900 mm
Guard height assessment: Guard height acceptable for most applications (hazard at 1000 mm)

Step by step

1Values used
2Reach through
3Reach over
4Safety distance required through the opening= 120 mm
5Limb that can pass the opening= Hand up to the knuckle joint
6Safety distance for reaching over the guard= 900 mm
7Guard height assessment= Guard height acceptable for most applications (hazard at 1000 mm)

Assumptions and limits

The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to whole numbers, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
Preliminary estimate only. Guarding must be designed to the applicable safety of machinery standards by a competent person using the full distance tables.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Preliminary estimate only. Guarding must be designed to the applicable safety of machinery standards by a competent person using the full distance tables.

Frequently Asked Questions

How is the Machine Guard Distance figure worked out?

Safety distance rises in steps with opening size: 2 mm at 4 mm opening, 20 mm at 8 mm, 120 mm at 20 mm, 850 mm above 30 mm. Safety distances for reaching through a regular opening depend on which part of the limb can pass.

Why do small increases in opening size matter so much?

Because the limb that fits changes discontinuously. Going from an 8 mm slot to a 12 mm one lets the whole finger through, and the required distance jumps from 20 mm to 100 mm.

What values do I need to enter?

This calculator takes 3 inputs: Opening size in the guard, Guard height, Hazard height above the floor. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.