Truss Load Calculator (Working Load Limit)
Quick answer: Enter span, manufacturer WLL, and all point loads. See utilization %, capacity remaining, and safety warnings.
Calculate truss utilization based on point loads (lights, motors, video panels, etc.) against the manufacturer's Working Load Limit (WLL). Uses the entertainment industry standard 10:1 safety factor (ESTA/PLASA recommendation). Built for production riggers, technical directors, and tour crews.
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Last reviewed: April 2026Report an error
From manufacturer chart.
10:1 default.
Point Loads
Within Limits ✓
47% utilized
Total load: 700 lbs of 1,500 lbs maximum (SF 10:1). Capacity remaining: 800 lbs.
Total Load
700 lbs
Max @ 10:1
1,500 lbs
Utilization
47%
⚠ All rigging must be inspected and signed off by an ETCP-certified rigger.
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The Formula
WLL_actual = WLL_chart × (10 / SF) ; utilization% = total_load / WLL_actual × 100
- WLL_chart = Working Load Limit from manufacturer at this span
- SF = Safety factor (10:1 industry standard for entertainment)
- total_load = Sum of all point loads (lights, motors, video)
Source: ANSI E1.2-2012 — Entertainment Technology Aluminum Trusses ↗
How to Use This Truss Load Calculator
- 1Enter the truss span between supports (in feet).
- 2Enter the WLL from the manufacturer's load chart at that span.
- 3Add each point load: name, weight per item, count.
- 4Optionally adjust safety factor (default 10:1 industry standard).
- 5Read utilization, remaining capacity, and warnings.
Frequently Asked Questions
- The maximum weight a truss section can safely support, derived from ultimate breaking strength divided by safety factor. ESTA standard for entertainment truss is 10:1 — meaning a truss with a 10,000 lb ultimate strength has a 1,000 lb WLL.
- Entertainment riggers fly equipment over people. The 10:1 factor accounts for dynamic loads (swing, motor jerks), repeated stress cycles, and the consequences of failure. Static structural engineering typically uses 5:1 — entertainment is more conservative.
- No — you must use the WLL value from the manufacturer's load chart for YOUR specific span. Truss capacity decreases with longer spans. A 30ft span carries far less than a 10ft span on the same truss.
- YES, ALWAYS. This calculator is a planning tool. Real rigging requires an ETCP-certified rigger or licensed structural engineer who evaluates: truss condition, attachment points, dynamic loads, secondary safety, building structure, and applicable building codes. Never fly without certified sign-off.
- Manufacturer WLL is typically based on a uniformly distributed load. Concentrated point loads at the center of a span have higher impact and should be derated. This calculator treats all loads as point loads (conservative). For exact UDL math, consult the manufacturer.
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