Truss Span & Load.

Add up every fixture you are hanging, multiplied by how many of each, including lamps, movers, speakers, screens, banners, motors and the clamps and cabling that go with them. This tool totals that hung weight for you as you add each item, and also shows an average distributed load in kilograms per metre across the span. Remember the truss itself, plus any motors and bumpers, adds dead weight on top of what you hang.

The centre of gravity is the single point along the span where all the hung weight effectively balances. If it sits well off the middle, one pick-up or leg carries far more load than the other, which can overload that point even when the total weight looks fine. Aim to spread heavy items so the centre of gravity sits near the midpoint between your support points, which is exactly what the Centre load button on this tool nudges it toward.

A uniformly distributed load is weight spread evenly along the whole truss, usually quoted in kilograms per metre, while a point load is a concentrated weight hung at one spot, like a single heavy mover or a line array pick-up. Manufacturer load charts almost always rate a truss far higher for an evenly spread UDL than for one or two heavy point loads in the middle. The average distributed figure this tool gives is a planning guide only, so always check your concentrated loads against the chart as well.

No. It totals the weight you are hanging and shows where the centre of gravity sits, but it does not certify that a truss is safe. Real capacity depends on the make and model, the span between supports, the number of pick-up points, and whether it is dead-hung from motors or ground-supported on towers. Always confirm against the manufacturer's load chart, work to a sensible safety factor, and have the rig signed off by a qualified rigger.

The longer the unsupported span between your two support points, the less weight the truss can safely carry, because deflection and bending stress climb sharply as the span grows. Halving the distance between pick-ups can dramatically increase the safe load, so adding a third support point or shortening the bay is often the easiest fix when a chart says you are over. Enter your real span in this tool first, since the distributed load and centre of gravity readings both depend on it.