Most LED light bulbs will include a Kelvin or K rating which indicates the color temperature. Color temperatures over 5,000K are called cool colors (bluish white), while lower color temperatures (2,700–3,000 K) are called warm colors (yellowish white through red). Some enjoy the bright white lighting as others may enjoy more yellowish lighting. There is also the blue hue that is more natural compared to daylight.

The color temperature has important applications of lighting, working, reading, displaying, etc. The color temperature light source is measured of an ideal black-body radiator or pure black that radiates light of comparable hue to that of a light source. Color temperature is typically stated in units of absolute temperature or Kelvin with the symbol K.

Sometimes by mistake, cool and warm fluorescent tubes were mixed and notably different color shade of white and yellow. The chart below gives a better understanding of the different color temperatures. For information on brightness, vist the watts to lumens table.

courtesy of Mifsud26

In December 2007 the U.S. federal government enacted the Energy Independence and Security Act of 2007, which requires all general purpose light bulbs that produce 310–2600 lumens of light be 30% more energy efficient than the current incandescent light bulbs by 2012. The efficiency standards will start with the 100 watt light bulbs in January 2012 and end with 40 watt light bulbs in January 2014. So if we are no longer measuring the brightness of 60 or 100 watt light bulb, what will we measure the brightness in? According to the European Union standard, an energy efficient bulb that claims to be the equivalent of a 60 watt tungsten bulb must have a minimum light output of 806 lumens and a 100 watt bulb should have a minimum 1343 lumens. A 23 watt compact fluorescent lamp emits about 1500–1600 lumens.

What are Lumens?

When we measured light bulbs in watts we knew how bright they are. Now if an LED or CFL light bulb consumes 15 watts and produces the equivalent of 60 watts, do we call it 15 watts or 60 watts? We'll change the light bulb rating description from watts to light intensity of lumens but, what is lumens? Without all the technical verbiage, efficiency is measured by the number of lumens per watt a light bulb provides. Lumens tell us how bright a light bulb is. Watts tell us how much energy the light bulb uses.

How do light bulbs compare?
• The standard 60 watt incandescent light bulb provides 13 to 14 lumens per watt.
• An equivalent CFL provides between 55 and 70 lumens per watt.
• An equivalent LED can range between 60 and 100 lumens per watt.

If you look at the box of the statndard tunsten bulb, it should have the watts and the lumens rating on the box to choose the right replacement LED Bulb.

Click here to see a conversion table.