Entertainment Rigging Calculator
Estimate event rigging loads from fixtures, truss span, hoist count, point-load share, cable and power adders, bridle angle, dynamic factor, and safety factor.
⚙Concert and Theater Presets
🎧Event Load Inputs
📊Entertainment Rigging Spec Grid
📋Dynamic and Use Case Reference
| Event condition | Planning factor | Use when | Watch item |
|---|---|---|---|
| Static draft | 1.00 | Early estimate before final design | Do not use as approval |
| Controlled indoor dead hang | 1.05 to 1.10 | No moving scenic, low vibration | Verify trim method |
| Typical concert or theater | 1.15 | Normal hoist trim and show reserve | Clustered fixtures |
| Movement, vibration, outdoor screen | 1.25 to 1.30 | Video wall, wind watch, moving loads | Engineering review |
| Critical conservative screen | 1.50 | High consequence preliminary check | Exact stamped plan |
⛓Bridle Angle Reference
| Angle above horizontal | Two-leg multiplier | Per-leg tension for 1000 lb point | Planning note |
|---|---|---|---|
| 75° | 0.52 × point | 518 lb | Open angle, lower tension |
| 60° | 0.58 × point | 577 lb | Comfortable planning geometry |
| 45° | 0.71 × point | 707 lb | Common estimate, watch headroom |
| 30° | 1.00 × point | 1000 lb | High tension, avoid if possible |
| 20° | 1.46 × point | 1462 lb | Very high tension, engineer |
💡Fixture and Cable Load Reference
| Rigging item | Typical planning weight | Often missed adder | Load check affected |
|---|---|---|---|
| LED wash or profile fixture | 18 to 45 lb each | Clamp and safety cable | Point share and truss load |
| Touring moving light | 55 to 95 lb each | Dual clamp hardware | Hoist and bridle tension |
| Audio delay or small array bar | 150 to 800 lb total | Dedicated steel and motors | Roof point approval |
| LED video header or scenic bay | 15 to 45 lb/ft | Power distro and data | Dynamic factor and point share |
| Cable loom and feeders | 3 to 12 lb/ft bundle | Slack loops at motors | Total suspended load |
🎛Hoist and Point Share Reference
| Support layout | Ideal equal share | Screening share to try | Reason |
|---|---|---|---|
| Two hoists, centered load | 50% each | 55% to 60% | Small offsets matter quickly |
| Three hoists, mixed fixtures | 33% each | 40% to 45% | Middle point can attract load |
| Four hoists, even truss | 25% each | 32% to 38% | Real trim rarely shares perfectly |
| Six or more hoists | 17% or less | 25% to 30% | Stiffness and level errors dominate |
| Offset video or scenic cluster | Varies | 45% to 60%+ | Calculate with actual geometry |
💡Rigging Calculation Tips
You must understand the weight that is suspended overhead in order to determine whether the structure below the weight can support the weight that is to be supported. The truss, the motors, and the bridle legs must be considered when calculating the load that will be present in each of these component. The entertainment rigging calculator performs the mathematical calculations necessary to determine the tension in each component of the rigging system.
However, you must make a series of decisions prior to utilizing such a calculator. The weight of the lighting fixture must be considered. The weight of the fixtures isnt the weight that is listed for each brand of moving light.
How to Calculate Lighting Rigging Loads
The listed weights does not include the weight of the dual clamp, the safety cable, the feeder tail, and the quick-connect hardware that will be attached to the light. The weight of the light increases with the addition of this hardware. The number that is entered into the entertainment rigging calculator is the weight of the fixture that is to be used.
The span of the truss and the weight of the truss itself will also contribute to the total load of the rigging system. The weight of each type of truss is specific to the length of the truss spans. For example, thirty-foot spans of mid-duty truss can weigh a specific amount per foot of the truss span.
The weight of the truss itself will be distributed to each of the hoists that are chosen for the truss. However, the distribution of that weight is rarely equally distribute to each of the hoists. Each rigging system will experience error in the level of each of the hoists and the stiffness of each of the hoists.
These errors will cause the weight to be distributed to one specific pickup point of the hoists. The value that is entered into the entertainment rigging calculator for point share accounts for this even distribution of the truss load to the hoists. The angles of the bridle legs will impact the tension that is created within each of the bridle legs.
If the bridle angle is set to a shallow angle, the tension in each of the bridle legs will increase. The increase in tension isnt linear. At forty-five degrees in bridle angle, the tension is manageable.
However, if the angle is thirty degrees, the tension within each of the bridle legs will increase to a level that may not permit the use of available hardware. The user can enter the value for the bridle angle into the entertainment rigging calculator to determine whether the selected points on the roof will be able to support the load after installation of the rigging system. The dynamic factor relates to the movement of the load that is to be suspended by the rigging system.
When calculating the static draft of the rigging system, it is assumed that the load will not move after it is trimmed to the proper hanging weight. However, during a performance, the load may move. Therefore, if there is to be any motion of the load, the user should increase the dynamic factor from the preset value in the entertainment rigging calculator.
The dynamic factor may be selected for each of the different types of production environments that may exist. A safety factor provides for the safety of the individuals in the production environment. The safety factor ensures that the load is always maintained with a certain distance from the working load limit of the rigging hardware.
Some venues will require the use of a safety factor of one-and-a-half. Other venues may require the use of a safety factor of two. This value can be entered into the entertainment rigging calculator to determine the total load that will exist with each of the components of the rigging hardware.
The weights of the power cables and electrical components will also contribute to the total load of the lighting rigging system. For example, if a bundle of power cables is to be used, it may appear to be a light load for the number of light that are to be controlled. However, if the cables are dressed and the lights are hung with the service loops, the bundle of power cables will add to the total load of the lighting rigging system.
In addition to the power cables, distro boxes, data splitters, and soft goods will add to the total load of the lighting rigging system. While these components will not impact the tension in each of the bridle legs, they will impact the total load that is to be supported by the rigging system and each of the pickup points. The reference tables will allow the user to determine what values should be entered into the entertainment rigging calculator.
For example, a dynamic factor of one point one five is used for most show planning efforts. The bridle angle tables will allow the user to understand how tension increases with the decrease of the angle of the bridle leg. The point share table will indicate that the even distribution of the load to each of the hoists is rarely experienced in any actual rigging system.
These tables will not replace the stamped drawings of the rigging system. However, they will provide the users with an understanding of whether or not there entries into the entertainment rigging calculator are within the normal operating ranges for the components of a lighting rigging system. Many people make mistakes in the hanging of lighting rigging systems.
For instance, many people do not include the weight of the dual clamp and the safety cable to the weight of the fixtures. People may assume that the capacity of the hoists are the available capacity of the rigging system, but that is not true; the capacity of the hoists is the working load limit for that component of the lighting rigging system. Finally, the angle that is selected for the bridle legs may look good for the plot of the production, but the tension may be too great for the shackle that is to be used in the hanging of the lights.
In each of these instances, people must enter the correct number into the entertainment rigging calculator in order to determine the mathematical consequence of their actions. The value of the entertainment rigging calculator is that it forces each member of the production crew to consider the number. For instance, if the design of the rigging system shows that the point utilization will be high after the safety factor is applied to the system, the designer may have to make a decision as to whether the safety factor that is to be applied to the system is sufficient to allow for the use of that rigging system.
Additionally, if the tension that is indicated within each of the bridle legs is too high for the lighting rigging system, the designer may have to make a decision as to whether the angle for each of the bridle legs should be changed or whether there should be another pickup point established for the load of the lighting fixtures. Finally, if the design load of the lighting fixtures is too great for the roof point that is to be used, the lighting designer may have to make a decision as to how to fix the design of the lighting rigging system prior to the lighting load is to be lift. In the final instance prior to lifting the lighting load, it is necessary to examine the load path of the lighting fixtures.
Each component of the lighting rigging system has a specific load that is to be supported by the other components. The load path should be examined using the actual weights of the components, the actual geometry of each component of the system, and the actual working load limits of the components. The entertainment rigging calculator can expedite this process.
However, it is up to each individual rigger to make sure that the lighting load is safely rigged for the performances that are to occur.
