Our Light Shield Calculator

Protect Neighbors and Preserve Night Skies

Outdoor lighting can brighten our spaces but may unintentionally affect neighbors and obscure the night sky. Many lighting ordinances do not allow light trespass. How do you ensure light fixtures are shielded to prevent light trespass before they are even installed? DarkSky Texas offers this calculator to help you determine the appropriate shield depth for outdoor lights, ensuring they illuminate only where needed.

Remi Boucher Graphic Shielding Color Temp Intensity Timing copy

Why Use This Calculator?

Improperly aimed or overly bright outdoor lights can cause glare, waste energy, and contribute to light pollution. By calculating the minimum shield depth, you can:

  • Reduce glare and improve visibility
  • Prevent light from spilling into neighboring properties
  • Conserve energy by directing light efficiently
  • Support local wildlife and human health by minimizing light pollution

This tool is designed for builders, lighting inspectors, homeowners, and community members aiming to make informed lighting choices.

How It Works

To use the calculator, input the following:

  1. Proposed Shield Length (in inches): The longest side of the lighting element to be shielded.
  2. Ground Elevation at Light Installation: The elevation of the ground where the light is mounted. An app or  topographic map will provide this data. This number and the ground elevation at the property line or location being protected are used to determine the difference in the ground elevation between the two locations.
  3. Mounting Height of Light (in feet): The height from the ground to the light source.
  4. Distance to Property Line or Location being Protected (in feet): The horizontal distance from the light being shielded to the property edge or to the off-site location to be protected from light trespass.
  5. Ground Elevation at Property Line or Location being Protected: The elevation of the ground at the off-site location to be protected from light trespass by the shield. This may be directly across the property line or at another location on a property other than the one where the light is or will be installed. This number and the ground elevation where the light is installed are used to determine the difference in the ground elevation between the two locations.

The calculator will provide:

  • The angle of light reaching the ground and eye level at the property line
  • The minimum shield depth required to block light at ground level
  • The minimum shield depth required to block light at eye level

These results help you design lighting that is effective and neighbor-friendly.

Light Shield Calculator Image v2

Benefits of Proper Shielding

  • Enhances nighttime visibility and safety
  • Prevents light trespass into adjacent properties
  • Reduces energy consumption by focusing light where it’s needed
  • Helps maintain the natural night environment for wildlife and people

Use the Calculator Below

Enter your measurements into the calculator to determine the appropriate shield depth for your outdoor lighting. If you’re unsure about ground elevations, consider using an online elevation finder tool or topographical map.

Variable to Enter Pertaining to this Specific Light Fixture

Installation and Location Variables



Need Help?

If you have questions or need further guidance, please contact DarkSky Texas. We’re here to help you make lighting choices that benefit both your property and the broader community.