# Lighting Formulas

Listed below are some useful stage lighting formulas which will allow you to convert units, work out beam diameters, etc.

**Light output calculations**

Lux = candela / (distance in metres x distance in metres) ie distance in m squared.

Foot-candles = candela / (distance in feet x distance in feet) ie distance in ft squared

**Power**

Watts = Volts * Amps

Amps = Watts / Volts

**Light Beam calculations**

Beam diameter = distance * (2 * tan(beam angle / 2))

Throw distance = Square root ((horizontal dist. * horizontal dist.) + (vertical dist. * vertical dist.))

**Unit conversions**

inches = millimeters / 25.4

millimeters = inches * 25.4

feet = meters / 0.3048

meters = feet * 0.3048

footcandles = lux / 10.8

lux = footcandles * 10.8

lux = footcandles * 10.8

Centigrade = 0.556 * (Fahrenheit - 32)

Fahrenheit = 1.8 * (Centigrade + 32)

Fahrenheit = 1.8 * (Centigrade + 32)

pounds = kilograms * 2.205

kilograms = pounds * 0.454

kilograms = pounds * 0.454

degrees = 180 * radians / PI

radians = PI * degrees /180

Sine Wave (VAC)

RMS Volts = 0.707 x Peak Volts

RMS Volts = 1.11 x Average Volts

Peak Volts = 1.57 x Average Volts

Peak Volts = 1.414 x RMS Volts

Average Volts = 0.637 x Peak Volts

Average Volts = 0.9 x RMS Volts

radians = PI * degrees /180

Sine Wave (VAC)

RMS Volts = 0.707 x Peak Volts

RMS Volts = 1.11 x Average Volts

Peak Volts = 1.57 x Average Volts

Peak Volts = 1.414 x RMS Volts

Average Volts = 0.637 x Peak Volts

Average Volts = 0.9 x RMS Volts

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