KelvinPlan is an independent site that works out lighting levels, fixture counts and layouts by room type and size.
It exists because lighting is sold in watts and bought in fittings, while the number that decides whether a room works is lumens — and almost nobody puts the room, the target and the fixture count on the same page.
Where the numbers come from
- IES recommended illuminance levels for residential spaces
- the ceiling-height-over-two spacing rule published in Halo, Lithonia and Juno installation guides
- HVI and ASHRAE 62.2 airflow requirements for bathroom exhaust
Every page states the source and the assumptions behind its figures, because a number without its assumptions is not much use. Where a level is a recommendation rather than a requirement, the page says which it is.
Lumens per fixture is the useful half
Layout calculators stop at the fixture count, which is the easy half. The useful output is lumens per fixture, because that is the number you actually choose between on the shelf.
What this site does not do
We do not design commercial or emergency lighting. Those are governed by codes and photometric requirements this site does not attempt to cover.
Who runs it
One person, doing this alongside other work. There is no editorial team and pretending otherwise would help nobody. Every figure here names the IES table or manufacturer guide it came from, so you can check it.
The lighting maths runs as code across every room type and size on the site, which is how a wrong constant gets caught — it would be wrong in hundreds of places, not one. When something is wrong it gets corrected, and the change is noted on the page.
How it is paid for
KelvinPlan is free to read and funded by display advertising. No sponsored placements and no affiliate links. No fixture brand has any influence on what these pages recommend.
Getting in touch
Corrections and questions go to [email protected]. Corrections are the most useful thing you can send — the editorial policy explains how they are handled.