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eng.led-efficacy-lifetime Calculator
Calculates LED luminous efficacy (lm/W) and estimated lifespan from driver efficiency and LED thermal resistance. LED efficacy has increased from 30 lm/W in 2005 to 150–200 lm/W for current phosphor-converted white LEDs — far exceeding incandescent (15 lm/W) and halogen (25 lm/W).
Inputs
Luminous Flux Lm
Reference formula or conversion factor shown for context.
Input Power W
Rate of energy transfer (W). P = V×I (electrical). P = F×v (mechanical). 1 horsepower ≈ 746 W.
Lumen Maintenance Pct
Reference formula or conversion factor shown for context.
Test Hours
Reference formula or conversion factor shown for context.
Drive Temp C
Thermal state of the substance. Check whether the formula needs Celsius, Fahrenheit, or Kelvin (K = °C + 273.15).
Results
luminous efficacy (lm/W)
Lumens produced per watt of electrical power (lm/W). Incandescent: 10-15 lm/W. LED: 80-200 lm/W. Higher efficacy = more light for the same energy.
estimated L70 life (hours)
The result expressed in hours. Divide by 24 to convert to days.
L70 life (years at 8hr/day)
The value at the specified point or condition.
temperature derating
A standardised quality or risk rating on the applicable scale.
typical LED efficacy
CAC (customer acquisition cost) -- total sales and marketing spend divided by new customers acquired. Healthy LTV:CAC ratio is 3:1 or higher.
L70
Reference formula or conversion factor shown for context.