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Fixture Count Calculator

Turn a target illuminance and room size into a fixture count and a rectangular row and column layout.

Inputs

Room

Sets the illuminance target for the space.

Longer side of the space.

Shorter side of the space.

Switch to metres for metric drawings.

Type a value to work to a client or code target instead of the default for the space.

Fixture and losses

Delivered lumens of the planned luminaire, from the photometric file or product label.

Share of fixture lumens that reaches the work plane. High bay in a racked warehouse 0.6 to 0.8.

Light lost to dirt and ageing before the next cleaning.

Input wattage of the planned fixture, driver included.

Result

Floor area
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Fixtures required
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Lumens required at the source
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Target illuminance
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Columns
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Fixtures in the grid
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Rows
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Illuminance of the grid
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Connected load
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Power density
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What this means
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What to check

  • Room dimensions to the lit boundary, not the building outline
  • Delivered lumens and wattage of the proposed luminaire
  • Rack heights and aisle widths, which decide the mounting height and the utilization factor
This calculator is a first-pass screen. A racked warehouse, a space with tall obstructions, or a room with dark surfaces changes the utilization factor enough to move the count by fifteen percent or more, so confirm the layout with a photometric study before ordering.

Saved calculations

Keep the assumptions with the result.

Save this calculation to return to the inputs, result, and report anytime.

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