Photometry Basics

Lighting Fixture Count Calculator

Estimate the number of luminaires needed for an area and target maintained illuminance.

Lighting calculator Photometry Basics Updated August 26, 2026

Inputs

Results

Fixture count --
Required initial lumens -- lm
Installed lumens -- lm
Estimated maintained illuminance -- lux
Calculation details
Fixture count
--
Required initial lumens
-- lm
Installed lumens
-- lm
Estimated maintained illuminance
-- lux
Maintained illuminance margin
-- lux
Important notes
  • The rounded fixture count does not confirm spacing, uniformity, glare, mounting, or product suitability.
  • Australian standards and project targets require current, task-specific review; this calculator does not declare compliance.

Formulas

  • \(\displaystyle N = \left\lceil \frac{E \times A}{\Phi_{\mathrm{luminaire}} \times UF \times MF} \right\rceil\)
  • Luminaire output must be distinguished from bare-lamp lumens.

Estimate the number of luminaires needed for an area and target maintained illuminance.

Lighting Fixture Count Calculator is a planning aid. Keep the target source, product data, measurement method, and project assumptions with the result. Confirm compliance, installation, certification, and safety decisions with the responsible professional.

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FAQs

Why is the fixture count rounded up?

A fractional fixture cannot be installed, so the estimate rounds the required count up to the next whole luminaire.