Lighting fixture count calculator

Preliminary estimate

Inputs

Calculation note

This estimates fixture quantity only. Uniformity, glare, spacing, optics, mounting height, emergency lighting, and photometric layout remain separate.

Method

Required lumens = target lux x area / light loss factor

Fixture count = required lumens / lumens per fixture, rounded up

Average raw lumens per m2 = fixture count x fixture lumens / area

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Formula variables

  • Target lux is the planning illuminance target.
  • Area is the space area in square metres.
  • Lumens per fixture is the entered product output.
  • Light loss factor adjusts the required lumens upward.

Assumptions

  • The calculator estimates quantity only and does not place fixtures in a layout.
  • Fixture lumen output is entered from product data.
  • Light loss factor is entered by the user for preliminary planning.
  • This calculator does not replace photometric design, workplace requirements, emergency lighting review, or manufacturer layout data.

Examples

Office-style planning. 500 lux over 80 m2 with 4000 lm fixtures and 0.80 light loss estimates 13 fixtures.

Design workflow. Use this count as a starting point before photometric layout, mounting height, optics, and controls review.