Light Pollution Calculator

Estimate light pollution from outdoor lighting by calculating wasted lumens, energy cost, and sky brightness impact.

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lumens
%
watts
hours
USD/kWh

Wasted Lumens

12,000 lumens

Wasted Energy per Year548 kWh
Annual Wasted Cost82 USD
Total Annual Lighting Cost274 USD

Wasted Lumens vs Electricity Rate

View formula & how it works →

How to Calculate Light Pollution

Light pollution is wasted light that shines upward or sideways instead of illuminating the intended area.

Formula

Wasted Lumens = Fixtures * Lumens * Uplight %

Wasted Energy = Total Energy * Uplight %

Types of Light Pollution

  • Skyglow: Brightening of the night sky over populated areas
  • Glare: Excessive brightness causing visual discomfort
  • Light trespass: Light falling where not needed
  • Clutter: Excessive groupings of light sources

    • Fully shielded fixtures eliminate uplight and reduce waste by 30-60%.

    Example Calculation

    10 fixtures at 4,000 lumens each, 30% uplight, 50W each, running 10 hours/night at $0.15/kWh.

    1. 01Wasted lumens: 10 * 4,000 * 30% = 12,000 lumens
    2. 02Annual energy: 10 * 50 * 10 * 365 / 1,000 = 1,825 kWh
    3. 03Wasted energy: 1,825 * 30% = 548 kWh
    4. 04Wasted cost: 548 * $0.15 = $82/year

    Frequently Asked Questions

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