Three-way bulbs come in several wattages. An easy way to differentiate between a three-way CFL and a standard three-way bulb is the CFL uses about one-fourth the watts. For example, if you are replacing a standard incandescent three-way bulb with a wattage rating of 40/75/100, a three-way CFL bulb would be about one-fourth the wattage rating or 11/20/26.
Consider where you will be using the three-way bulb. Three-way bulbs typically come in a warm white color with a Kelvin (K) temperature rating of 2700K. There are also bulbs available in soft white 3000K, or a cool white/bright light, of 3500K to 4100K.
More Information on the Department of Energy website