Theatre Angle Calculator

Tilt, beam circle, and beam footprints. Distances in meters. Tilt convention: 0° = horizontal, 90° = straight down.

Tilt: α

Beam angle: θ = 2·atan(D / (2·s))

Floor footprint: ellipse at z = 0

Wall footprint: ellipse at x = d

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Inputs

m / degrees

Units

a) Truss height (m)

b) Target offset from Z axis (m)

c) Target centre height (m)

d) Desired lit area diameter D (m)

Enter the desired lit diameter at the target. The calculator derives the required beam angle θ. Footprints are intersections of the beam cone with the floor plane (z = 0) and the wall plane (x = d).

Results

Tilt below horizontal α

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Height difference Δh (truss − target)

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Angle to vertical β

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Axis distance lamp → target s

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Computed beam angle θ (full angle)

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Target beam circle diameter D

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Target beam circle radius R

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Floor footprint ellipse (major × minor)

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Floor footprint centre (x from Z axis)

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Wall footprint ellipse (major × minor)

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Wall footprint centre height (z)

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Diagram

2D side view (x–z)

The diagram is schematic (2D side view). Numeric ellipse diameters are the accurate outputs.