It can be very confusing to purchase compact fluorescent (CFL) or light emitting diode (LED) light bulbs because of the way the products are labeled. They state the equivalency of the light output to the old watt based ratings. IE 100 W equivalent or 100 W replacement. However, the real test is how much light is output, which is rated in lumens. And, the labeling is not always consistent.
The following chart makes it easy to convert the old light bulb measurement of watts to the new light bulb measurement of lumens for comparison to basic omnidirectional lamps. This way, you can see if that 100 W replacement bulb really is equivalent to the old 100 W bulb, for example. This chart is based on the US Government’s Energy Star program specifications as well as information for smaller bulbs from Wikipedia with the latter showing a range of +/- 10% from the nominal values.
Any new CFL or LED bulb you buy should produce at least as many lumens as the watt replacement that it says it is. For example, a 100 W replacement bulb should produce at least 1600 lumens. Note that the actual power consumption for CFL or LED bulbs will be much less. For example a CREE 100 W replacement LED bulb actually consumes 18 W of power.