Lighting
Light Fixture Spacing Calculator
Calculate fixture spacing from mounting height above task plane and spacing-to-height ratio. The default values illustrate the workflow; replace them with measurements or ratings from one documented condition.
Calculate Fixture spacing
Replace the examples with values from the same case.
From inputs to result
This page evaluates spacing = height × spacing ratio. The participating entries are Mounting height above task plane and Spacing-to-height ratio.
The defaults produce 2.88 m. Replace them with measurements from one operating state.
Calculate fixture spacing from mounting height above task plane and spacing-to-height ratio. Continue with Illumination Uniformity Calculator to evaluate uniformity ratio.
Applying the result
Use Fixture spacing as one quantified check within the larger decision. Compare it with illuminance, uniformity, driver loading, voltage loss, energy use, and maintained output.
A result without its source conditions is difficult to compare or audit. A connected part of the work can be checked with Light Beam Diameter Calculator.
Preparing the calculation
Use photometric data for the actual fixture, optic, mounting height, and task plane. Nameplate and meter values are not interchangeable unless they describe the same condition.
Use the displayed unit for every field and document conversions separately. The minimum row spacing step is handled by Solar Row Spacing Calculator.
- Mounting height above task plane
- Default example: 2.4 m. Enter mounting height above task plane in m.
- Spacing-to-height ratio
- Default example: 1.2. Enter spacing-to-height ratio.
Assumptions and limitations
Verify uniformity with fixture photometric data.
The surrounding system may introduce daylight variation, control behavior, depreciation, and spatial uniformity. Test an additional scenario when an omitted effect has a plausible range.
Record reflectance, maintenance condition, beam definition, and measurement location.
Documenting the calculation
Document mounting height above task plane and spacing-to-height ratio with fixture spacing. Keep enough context to reproduce the result later.
Carry fixture spacing unchanged when passing it to the next worksheet. Apply standard sizes only after all checks are complete.
Review the case step by step
Review mounting height above task plane and the remaining entries as one case. If one value belongs to another temperature, load, or time period, separate the scenarios.
Use fixture spacing alongside illuminance, uniformity, driver loading, voltage loss, energy use, and maintained output. Preserve the unrounded number until all dependent calculations and comparisons are complete.
If uncertainty remains, calculate labeled low and high cases. Include fixture distribution, reflections, mounting, maintenance, and meter position when those effects can change the decision.
Common questions before using the result
Where is this fixture spacing estimate simplified?
Verify uniformity with fixture photometric data. Also consider driver efficiency, optical loss, surface reflectance, and beam-edge definition.
What can cause a different fixture spacing reading?
Recheck units and operating state before investigating fixture distribution, reflections, mounting, maintenance, and meter position.
What is the cleanest way to test another scenario?
Keep unaffected entries fixed so the cause of the difference remains visible. Keep lumens, candela, lux, and foot-candles on the correct geometric basis.