PlanLumens, lux, and watts are three different questions
Brightness, light on a surface, and energy use belong in separate columns. Once they are separated, a lighting plan becomes much easier to read.
Plan · Brightness
Room lumens planner
Turn room dimensions and an adjustable target illuminance into a transparent lumen range and fixture count.
- Question
- How many lumens does this room need?
- Runs
- Locally in this browser
- Reviewed
- 2026-08-06
Live result
Planning range5,415–7,326 lm
Centered on 6,370 design lumens after the declared factors.
Fixture estimate8at 800 lm each
Room area192 ft²
Target200 lux18.6 foot-candles
Delivered target3,567 lmbefore utilization and maintenance allowances
Sketch only. Confirm fixture photometry, reflectance, glare, daylight, controls, and local requirements.
From number to decision
Measure.
Read. Verify.
A 16 × 12 ft room at 200 lux, with 0.70 utilization and 0.80 maintenance, produces a design estimate of roughly 6,370 lumens before fixture selection.
Measure
- Measure the finished internal length and width; exclude spaces that are separately lit.
- Choose an editable target based on the visual task, not only the room name.
- Use real fixture lumens, then state utilization and maintenance allowances.
Read
- The delivered target is area multiplied by target lux.
- The design total raises that value to account for the declared utilization and maintenance factors.
- The range is ±15% around the simplified estimate to discourage false precision.
Verify
- Manufacturer photometry or an IES/LDT file
- Surface reflectance, daylight, glare, vertical light, and controls
- A mock-up at the real working plane and eye position
The visible method
design lumens = area × target lux ÷ utilization ÷ maintenance
LimitA simplified lumen-method estimate cannot model fixture photometry, surface reflectance, daylight, glare, or local code.
Results are computed from the fields you enter. Glow & Gauge does not infer a product, electricity rate, room reflectance, or professional approval.
Read the site-wide methodStarting references
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