The beam angle of a lamp is the angle at which the light is distributed or emitted. Lamps such as Halogens (and some LEDs) come in a variety of angles from, 4 degree to 60 degree with some of the larger halogen lamps up to 120 degree.
Note that while these abbreviations are commonly used, the angles associated with these vary slightly from manufacturer to manufacturer. These are typical beam angles spread abbreviations.
SP (spot): 8-16 degrees
FL (flood): 20-40 degrees
WFL (wide flood): 40-55 degrees
VWFL (very wide flood): 60 degrees or more
For most domestic household ceiling fitted appliances a beam angle in the 30-40 degrees will be sufficient given the standard height of ceilings and the range, spread and number of light bulbs in the area. Please also note that the wattage, type of light bulb and colour used will also determine the beam angles available.
Please move your mouse over the interactive picture below, left for a narrower beam angle, right for a wider beam angle.