When I was growing up, my understanding of standard light bulbs was that there were four main levels of brightness: 40, 60, 75 and 100 watts. To this day, the general public commonly uses wattage to describe light output. Although wattage and light output have some connections, wattage is not a measure of light output at all. Wattage is simply a measurement of electrical power used. You could take a lit 60 watt bulb and paint it black and it would still be a 60 watt bulb spinning your electrical meter but giving you no light output at all.
The correct measurement for light output is the term "lumens". A lumen is a standard measurement of light to express quantity of light given off. For example, a dinner candle provides about 12 lumens and a 60 watt soft white incandescent lamp provides about 840 lumens. On the other hand, that same bulb painted black gives off zero lumens. A long life 60 watt bulb has less resistance and perhaps a thicker filament and may only give off around 500 lumens. It is now standard to print the lumen output of all incandescent on the package. This gives the consumer a much more educated idea of how that particular bulb is going to perform. With this in mind, it should be easy to see that all 60 watt bulbs are not alike.
If you are shopping in a grocery store, you can usually find the specifications of your lighting products simply by reading the package. If you are shopping on the internet, the best place to evaluate lighting options is here at eLightBulbs.com. When you get to your specific item, you will see displayed all of the factors pertaining to that specific bulb.
Not only does eLightBulbs list all of the specifications, if you are not familiar with a term, you can read more it directly on each product page! For your education, here are some other facts about light bulbs:
- Most bulbs are measured in 1/8" increments and this is displayed in their description. For example an A19 bulb is a standard light bulb that is 19-8ths of an inch in diameter. An R30 is a reflector that is 30-8ths of an inch in diameter. A PAR38 is an outdoor flood that is 38-8ths of an inch in diameter.
- Standard screw bases are measured in millimeters. A candelabra screw base is an E12 (Edison style 12mm in diameter). A standard screw base is an E26 (Edison style 26mm in diameter)
- All bulbs are given an average rated life. Many people mistake this for what they can expect from every bulb but it is an average. This means that if you bought 100 bulbs rated at 1,000 burning hours, by the time you reached 1000 burning hours, one half of your bulbs would already be burned out.
- All else remaining equal, a standard 60 watt bulb has 870 lumens, compared to a 60 watt halogen which has 960 lumens and lasts 3 times longer!