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- Conventional light bulbs are rated by their energy usage such as 40 watt or 100 watt as well as their size. Light emitting diode-equipped devices are given compatible ratings for easy cross-referencing. The energy output is given in a comparative fashion such as "13 watts, equivalent to 60 watt incandescent" or similar. A C9 or C7 LED bulb is the same size as its companion incandescent bulb. These are "retrofit lamps" which means they fit in the same socket as incandescent lights.
- The C7 light is about 1-1/2 in. by 1 inch wide and is one of the standard light bulb shapes and sizes used as Christmas lights for decades. The C9 light is larger at 2-1/2 inches high by 1-1/4 inches.
- The C7 LED requires 0.08 watts while a conventional C7 light bulb uses six times as much at 0.48 watts. Multiply this by the typical hundreds of Christmas lights on a tree and you have a great difference in energy consumption and heat generated. According to Washington State University, a typical incandescent Christmas light installation uses $9.26 in electricity. The LED C7 arrangement uses $0.30 in electricity cost. Figures are similar for the C9 LED versus a conventional light, since C7 and C9 LEDs use approximately the same amount of energy.
- C7 lights are the smaller of the two and emit less light, so they will seen less often in room lighting situations compared to the C9. The C9 clear bulbs provide light levels similar to a 7-watt incandescent lamp, so several are generally concentrated together to produce sufficient light, such as found in chandeliers. Since both of these bulbs are decorative, they are not typically used for everyday lighting.
Bulb Ratings
C7 and C9 Dimensions
Energy Usage Comparison
Mainly Decorative
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