The best tools are still paper and pen/ pencil if you just want to quickly sketch up a layout without having to learn the tools.

Thanks davidtay, the main question I have is do you use advertised lumens on the package when calculating lumens / sf, or do you multiply it down by a coefficient of utilization factor (e.g. which I've heard to be 0.77 for LR6 and CR6).

That one calculation changes the number of lights needed by about 30%. Most calculations I've seen on the Internet do include this factor but I haven't seen it discussed here.

I guess the other option would be to just increase the lumens / sq ft target value (which might be what's happening, because I've seen 25-30 lumens / sq ft in other places but have heard 35 lumens / sq ft on this forum).

This post was edited by calumin on Sat, May 18, 13 at 11:19

I use the advertised lumens. The formula works very well with the CR6/ 4 and RT6 type lights since that is the actual output.

If you have dimmers, the max output is typically reduced by 5%.