Bridle Calculator (Two-Point Rigging Math)
Calculate leg lengths, tensions, and angles for a two-point bridle — the standard rigging configuration when no overhead point sits directly above your pickup. Built for production riggers, ETCP candidates, technical directors, and tour crews. Math is pure statics (vertical load at apex, two inclined slings) — no proprietary tables involved.
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Last reviewed: April 2026Report an error
Enter your geometry — beam positions and pickup location — and the calculator returns sling lengths, tensions, and beam reaction forces.
Distance between the two beams.
Vertical drop A → apex.
Vertical drop B → apex.
0 = centered. + shifts toward B.
Manufacturer spec per sling.
5:1 default (entertainment).
Bridle Geometry
Blue dots: beam anchors. Orange dot: bridle apex. Red arrow: load. Apex included angle: 67.4°.
Within Limits ✓
18.03 / 18.03 ft
Leg A: 18.03 ft long, 300 lb tension, 33.7° from vertical. Leg B: 18.03 ft, 300 lb, 33.7°. Apex angle: 67.4°.
Leg A (to beam A)
18.03 ft long
300 lb tension · 33.7° from vertical
15% of sling WLL · order ≥ 20 ft sling
Leg B (to beam B)
18.03 ft long
300 lb tension · 33.7° from vertical
15% of sling WLL · order ≥ 20 ft sling
Beam Reaction Forces
Beam A
↓ Vertical pull (down): 250 lb
→ Horizontal pull (toward apex): 167 lb
Beam B
↓ Vertical pull (down): 250 lb
→ Horizontal pull (toward apex): 167 lb
Vertical pulls sum to load weight (500 lb ≈ 500 lb). Horizontal pulls are equal on both beams (Newton's 3rd) — verify your truss/steel attachment can resist this sideways load.
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The Formula
- H = Horizontal distance between the two beam anchors
- h_A / h_B = Vertical distance from each beam DOWN to the apex (can be different)
- X_A / X_B = Horizontal distance from each beam to the apex (X_A + X_B = H)
- L_A / L_B = Leg lengths = √(X² + h²)
- W = Total load weight at the apex
- T_A / T_B = Tension in each leg
- D = Common denominator for tensions = X_B·h_A + X_A·h_B (reduces to V·H when heights are equal)
How to Use This Bridle Calculator
- 1Enter horizontal distance (H) between the two overhead attachment points.
- 2Enter vertical drop (V) from the attachment plane down to the pickup/apex.
- 3Enter offset of the pickup from center (0 = symmetric bridle, positive = offset toward point B).
- 4Enter the total load weight at the apex.
- 5Enter the working load limit (WLL) of each sling from the manufacturer.
- 6Optionally adjust safety factor (default 5:1 standard for entertainment slings).
- 7Read leg lengths (for sling-size ordering), tensions, angles, and utilization.
Frequently Asked Questions
- A bridle is a two-leg sling configuration that supports a load between two overhead attachment points. Used when the pickup point is not directly under a single overhead point — e.g., centered between two steel beams, or offset to clear an obstruction.
- Pure static equilibrium. Vertical forces balance the load (sum of vertical components of leg tensions = load weight). Horizontal forces balance each other (the two legs pull in opposite directions). The math: T_A = W × X2 × L_A / (V × H), T_B = W × X1 × L_B / (V × H), where X1 and X2 are horizontal distances from each attachment to the pickup, V is vertical drop, H is total horizontal span, and L_A / L_B are leg lengths.
- As legs spread wider from vertical, tension goes up dramatically. At 30° from vertical, tension is ~15% above the load weight. At 60°, it doubles. At 75°, it nearly quadruples. Industry rule of thumb: keep legs under 60° from vertical (under 120° included angle at the apex). This calculator warns when you cross that line.
- Entertainment slings are typically rated at 5:1 (the manufacturer's WLL already accounts for this — that's the published Working Load Limit). For overhead lifts where the load might be over people, many production companies internally derate to 7:1 or 10:1 for additional margin. This calculator defaults to 5:1 (use full WLL) and lets you override.
- Symmetric: pickup is at the midpoint between the two attachments. Legs are equal length, equal tension. Asymmetric: pickup is offset toward one side. The leg on the SHORTER side carries MORE tension. The calculator handles both — set offset to 0 for symmetric, positive value for offset toward point B.
- No. This is a planning tool. Real overhead rigging requires an ETCP-certified rigger or licensed structural engineer who evaluates attachment-point capacity, dynamic loading (motor jerks, swing), sling condition, secondary safety, the structure being attached to, and applicable building/venue codes. Never fly equipment over people based on a calculator alone — get certified sign-off.
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