What components add up to required clearance?

Per ANSI Z359.11-2014: lanyard length + maximum deceleration distance (typically ≤ 1.07 m for shock-absorbing) + harness stretch (~0.3 m) + height of attachment point + safety margin (typically 0.6–1.0 m). Sum all five to get required clearance below the anchor.

What if my workplace can't fit the required clearance?

Use a self-retracting lifeline (SRL) with shorter deceleration, an overhead anchor instead of D-ring height, or a fall-restraint system that prevents the fall altogether. Many low-clearance jobs use Class A SRLs (decel ≤ 0.6 m).

Does the calculator account for swing?

Pendulum swing is not included — the result is for a vertical fall directly below the anchor. If the work position is offset, the worker can swing into adjacent structure; that's a separate hazard requiring its own assessment (anchor placement, swing-fall protection).

What's the difference between duty ratings?

OSHA 1926.451: Light 25 psf (122 kg/m²), Medium 50 psf (244 kg/m²), Heavy 75 psf (366 kg/m²). EN 12811-1:2003 Classes 1–6 range from 75 kg/m² to 600 kg/m². The class chosen must accommodate workers + tools + stored materials simultaneously.

Can workers stand on a 'storage only' scaffold?

Only if it's still within the chosen duty rating. A Class 5 EN 12811 platform (450 kg/m²) can carry a worker plus material — but a Class 1 platform rated only 75 kg/m² is for a single worker with tools, no material storage.

What about point loads (tools, gas cylinders)?

Distributed-load ratings assume uniform spread. Concentrated point loads (a stack of bricks, a gas cylinder) must be calculated separately against the deck's point-load capacity, typically 1.5 kN concentrated on 250 × 250 mm per EN 12811-1.

Why exactly 4:1 (75.5°)?

Steeper angles (over 80°) cause the ladder to tip backwards; shallower angles (under 70°) cause the foot to skid. 4:1 ratio (1 unit out for every 4 units up) puts the centre of gravity in the safest position and is the OSHA 1926.1053 / EN 131 standard.

How much should the ladder extend above the landing?

Per OSHA: 3 ft (≈ 0.9 m) above the landing for proper handhold. Per EN 131: at least 1 m above the upper support. The tool computes this and the total ladder length needed.

What if I can't get the 4:1 angle (e.g. against a curved tank)?

Use a ladder with a stand-off bracket that holds the foot at the correct setback, or use a different access method (scaffold tower, MEWP). Improvised foot-blocking is not safe practice.

Work-at-Height – Fall Clearance, Scaffold

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10Fall Clearance Calculator

Required clearance below the anchor = Lanyard + Deceleration + Worker height + Harness stretch + Safety margin. Compare against the actual fall distance to see if the worker would impact a lower level.

Lanyard type i

Lanyard length (m)

Deceleration distance (m) i

Worker height — D-ring to feet (m)

Harness stretch (m)

Safety margin (m)

Distance from anchor to nearest lower level (m)

Required vs available clearance

— m required

— m available

—

11Scaffold Load Calculator

Compare planned load (workers + tools + materials) against the duty rating chosen for the scaffold platform. Duty ratings follow OSHA 1926.451 / EN 12811-1:2003.

Scaffold type

Bay length (m)

Bay width (m)

Duty rating i

Number of workers on platform

Average worker mass + tools (kg)

Materials stacked on platform (kg)

Result

Platform area—

Permitted total load—

Planned total load—

Distributed planned load—

Utilisation—

—

Inspection reminders

Daily pre-use scaffold tag check by competent person.
Toe-boards, mid-rails and top-rails on all open sides.
Secure base plates / mud sills on stable ground.
No mixing of components from different manufacturers.

22Ladder Angle (4:1) Calculator

Single & extension ladders should sit at the standard 1:4 ratio (≈ 75.5°). Enter the working height to find the correct base setback, ladder length and required overlap above the landing per OSHA 1926.1053 / EN 131-1:2015+A1:2019.

Working / landing height (m)

2 m6.0 m14 m

Required extension above landing i

Ladder type

Single Extension Step

Base condition

Level / firm Uneven / soft Slippery

Tie-off / securing i

Tied off Not tied

Ladder geometry

— ° from horizontal

—

Base setback (1:4)—

Min ladder length—

Overlap above landing—

Notes—

For training purposes only. Scaffold loads must be authorised by a Competent Scaffold Inspector. Fall-arrest plans must be reviewed by a Qualified Person per ANSI Z359.

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Work at Height Calculators