Lighting
Illumination Uniformity Calculator
This page handles the arithmetic for uniformity ratio while leaving room to review units, limits, and source conditions.
Model Illumination Uniformity
Small unit changes can move uniformity ratio; confirm scale before using the result.
What uniformity ratio means here
Illumination Uniformity is most useful when the task is to calculate uniformity ratio from minimum illuminance and average illuminance. It keeps the arithmetic visible and separates that case from nearby electrical questions.
Illumination Uniformity changes with mounting height, beam shape, surface reflectance, and driver limits.
Average illuminance and the other entries
On Illumination Uniformity, confirm decimal placement and unit scale before using uniformity ratio; small prefixes can move an electrical result by orders of magnitude.
- Minimum illuminance. Example value: 280 lx. Enter minimum illuminance in lx.
- Average illuminance. Example value: 420 lx. Enter average illuminance in lx.
A separate Lux Lumens run is cleaner when that result becomes the real design question.
The Illumination Uniformity equation
Read the Illumination Uniformity equation from the units on this page. A familiar symbol can shift meaning between DC, AC, energy, component, or billing work.
A clean Illumination Uniformity result confirms the arithmetic for uniformity ratio; it does not prove the equipment rating or source data is the right one.
Only the entries shown on Illumination Uniformity feed uniformity ratio. If another correction factor matters, keep it in the notes or make a separate run.
If the next step shifts toward Foot-Candles Lux, keep that as a separate worksheet instead of forcing the numbers into Illumination Uniformity.
Sample Illumination Uniformity run
Using the sample values, Minimum illuminance = 280 lx; Average illuminance = 420 lx, the primary result is 66.67%.
This Illumination Uniformity one-input test is a scale check, showing direction and sensitivity without turning the changed case into a recommendation.
If the changed minimum illuminance comes from a real measurement, keep the original Illumination Uniformity run so the source of the difference remains clear.
Turning uniformity ratio into a decision
The result card gives a comparison point for Illumination Uniformity. Equipment ratings, safety margins, and manufacturer limits still need their own check.
Illumination Uniformity changes with mounting height, beam shape, surface reflectance, and driver limits.
A separate Daylight Factor run is cleaner when that result becomes the real design question.
When your notes point to Inverse Square Lighting, open it after saving this baseline so the two cases do not get mixed.
What not to assume from Illumination Uniformity
Use readings from a documented measurement grid.
- Fixture spacing
- Beam angle
- Dimming compatibility
When uniformity ratio is close to a rating, use the stricter review path instead of relying on the extra decimals shown by Illumination Uniformity.
Notes to save with Illumination Uniformity
Keep fixture model, mounting height, distribution angle, and target plane with the Illumination Uniformity result.
| Input set | Minimum illuminance, and Average illuminance |
|---|---|
| Result | Uniformity ratio |
| Condition note | Use readings from a documented measurement grid. |
Common Illumination Uniformity questions
What should be recorded with the answer?
Save the Illumination Uniformity inputs, unit basis, operating case, and result note so uniformity ratio can be reproduced later.
Why did the answer move so much after one input changed?
Many electrical relationships are proportional, inverse, squared, or tied to a denominator. A small change in minimum illuminance can have a visible effect when the other entries stay fixed.
When should this be run again?
Run a new Illumination Uniformity case when the source condition changes, such as voltage, load, rate schedule, temperature, component, connection, or period.
Can the default values be used as a recommendation?
No. The Illumination Uniformity defaults only demonstrate the form. Replace them with measured or rated values for the actual lighting case.
Which value should be rounded first?
Keep minimum illuminance at source precision during Illumination Uniformity; round uniformity ratio only where presentation or purchasing requires it.