What the Bathroom Lighting Calculator actually calculates
Ambient lumens are area times lux, and vanity lumens are vanity width times the entered output per metre. Their sum is a planning total, not a measured lighting level. The engine does not assess face-lighting uniformity, mirror reflections, fixture positioning, or required electrical protection and moisture ratings.
The calculation path
Room area sets ambient lumens and vanity width sets face-lighting output.
Inputs that can change the answer
- Bathroom area: Enter bathroom area in m².
- Vanity width: Enter vanity width in m.
- Ambient target: Enter ambient target in lux.
- Vanity lumens per metre: Enter vanity lumens per metre in lm/m.
Checks that stay outside the formula
Select fixtures with the required local wet-zone or IP rating.
A practical order for entering the data
- Enter the bathroom floor area and intended ambient lux.
- Measure the vanity width and choose a vanity output target in lumens per metre.
- Review the ambient and vanity layers separately, and verify local wet-zone requirements for every proposed fixture location.
Project walkthrough: Plan bathroom lighting without treating a lumen figure as approval
Engine check using the prefilled sample
Lighting example: bathroom area = 8 m², vanity width = 1.2 m, ambient target = 250 lux and vanity lumens per metre = 1000 lm/m. Treat these as demonstration room and fixture values, then recalculate with the dimensions and rated output of the fittings you are considering.
Results for these inputs
- Ambient lumens
- 2,000 lm
- Vanity lumens
- 1,200 lm
- Total planned lumens
- 3,200 lm