IEC e-tech > January/February 2013 – Think lumens not watts.
For decades, choosing a new or replacement light bulb has been easy: consumers would look at the wattage … (however) replacement of incandescent bulbs by energy-efficient products… introduced confusion … as … producers often only gave the watt equivalent of the new bulbs. … The situation is no clearer now that LED-based lamps are becoming more popular and increasing in efficiency all the time.
Watts indicate the power needed to light the bulb, and lumens indicates the amount of visible light emitted by a source. The value of the bulbs required may differ according to the lighting effect desired. The table in the article gives average ratings for incandescent, CFL and LED bulbs.