Scaffold Load Capacity Calculator

Calculates maximum intended load, required minimum structural capacity per OSHA 29 CFR 1926.451(a), duty rating classification, and per-support-point load distribution.

Critical safety context: OSHA 1926.451(a)(6) requires scaffolds to be designed by a qualified person and constructed/loaded in accordance with that design. This calculator performs the standard 4:1 (or 6:1 for suspension rope) safety-factor arithmetic only — it assumes uniform load distribution across support points and does not account for wind, dynamic/impact loading, uneven loading, ground/foundation bearing capacity, or component-specific ratings. A qualified person must design the scaffold and a competent person must inspect it before each work shift.

Build the Maximum Intended Load

Number of Workers on Platform

Assumed Weight per Worker (lbs) 250 lbs (incl. PPE & hand tools) is a common conservative planning assumption.

Materials & Equipment Weight on Platform (lbs)

Scaffold Configuration

Scaffold Type

Number of Support Points / Legs

Platform Area (sq ft) Used to classify duty rating (Light/Medium/Heavy) — length × width of the working platform.

0 lbs

Maximum Intended Load

0 lbs

Required Min. Capacity

0 lbs

Load per Support Point

Formula Reference

Maximum Intended Load (MIL) = (Workers × Weight per Worker) + Materials & Equipment Weight
Required Minimum Capacity = MIL × Safety Factor (4 for standard scaffolds, 6 for suspension rope) — per OSHA 1926.451(a)(1) & (a)(3)/(a)(4)
Load per Support Point = MIL ÷ Number of Support Points (assumes uniform distribution)
Load per Square Foot = MIL ÷ Platform Area

Common Duty Rating Classifications

Light Duty	≤ 25 lb/ft² — e.g., inspection, painting
Medium Duty	≤ 50 lb/ft² — e.g., general construction, masonry (matches OSHA App. A masons' scaffold rating)
Heavy Duty	≤ 75 lb/ft² — e.g., stone/masonry material storage on platform

These duty-rating bands are a widely-used industry convention (consistent with ANSI/ASSP scaffold guidance), not a numeric mandate written directly into OSHA 1926.451 itself — always confirm against your scaffold manufacturer's rated capacity.