Very bright. I normally calculate around 1.5W/sq. foot, but that's too bright for this equation. I think you could get 1 W/sq. foot or 40 square meters. Feet per fixture with these devices. I use a manufacturer recommended $22 Lutron LED specialty dimmer and they won't turn on with that specialty dimmer on the lowest setting. There's a delay when it's turned on at every level, from two seconds in very low light to barely noticeable in the brightest light. However, I like the ease of installation and the clean, simple look.