You can find the brightness in lumens
right on the front of the package.
Click to enlarge
Brightness is a description of light output, which is measured in lumens (not watts). Light bulb manufacturers include this information and the equivalent wattage right on the packaging. Common terms are "soft white 60," "warm light 60," and "60 watt replacement." Sometimes a diagram will show two images with an equal sign, as in the packaging image to the right.
To save energy, find the bulbs with the light output you need, and then choose the one with the lowest wattage. You can also look for an ENERGY STAR certified bulb that is labeled as equivalent to the incandescent bulb you are replacing.
The color of light may also affect how bright a light appears, even if the lumens are the same. Since most people are used to the soft yellowish glow from incandescent light bulbs, ENERGY STAR certified bulbs that produce light closer to the color of daylight (color temperatures above 3000K) may appear brighter because the color of the light is less yellow. Learn more about color temperature.
Old Incandescent Bulbs(Watts)
ENERGY STAR Bulb Brightness(Minimum Lumens)