Understanding Lumens

New Light Bulb Labels – Understanding Lumens

Energy efficiency is changing the way you decide which light bulb to buy. Understanding the new light bulb labeling will make your decisions easier and better informed.

Historically if you wanted a certain amount of light you would buy bulbs based on their wattage rating.

Wattage is a measure of energy. If you wanted bright lighting you might choose a 100 watt bulb because you knew they generated a lot of light. The measure of wattage was a simple way to quantify light when there weren’t many choices in bulb technology. When everything was the standard incandescent bulb, using watts was a great “rule of thumb” for comparison.

An energy efficient LED, that uses only 25 watts of energy, emits the same amount of brightness as the former 100 watt incandescent bulb!

Energy efficiency is changing all that. There is a growing variety of lighting technology and you end up comparing apples to oranges when you simply measure the amount of energy they use. Energy usage does not tell you how much light they create. If you replaced a 100 watt incandescent bulb with a 100 watt LED the light would be overpowering!

Lumen: a unit of luminous flux equal to the light emitted in a unit solid angle by a uniform point source of one candle intensity. Merriam-Webster

Lumens (lm) on the other hand measure the amount of brightness or light generated. The new light bulb labels will allow you to choose bulbs based on the amount of lumens generated instead of how much energy is needed to create the light. It is a much easier way to compare different light bulb technologies but it will take some getting used to. Instead of buying a 60 watt bulb you will look for an 825 Lumens bulb. The available bulbs could be incandescent, LED, fluorescent, or CFL. With each choice you will get the same amount of light but you will not necessarily get the same energy efficiency.

Incandescent Bulbs


40 watt

450 lm

60 watt

825 lm

75 watt

1100 lm

100 watt

1600 lm

150 watt

2600 lm

If you’re energy conscious you will want to buy bulbs that give you the right amount of light using the lowest use of energy.

One way to judge energy efficiency is to compare the amount of light generated (lumens) to the energy required to generate the light (watts). That efficiency value is known as lumens per watt. A typical incandescent bulb will generate 12 lumens per watt. In comparison an energy efficient induction light bulb will generate close to 120 lumens per watt. That translates to a huge savings in your energy bill because you’re only using 10% of the energy to achieve the same amount of light!

Image courtesy of kraifreedom / FreeDigitalPhotos.net

Image courtesy of kraifreedom / FreeDigitalPhotos.net

The green movement is making us more aware of energy efficiency and long term sustainability. The quest for energy efficiency is creating monumental changes in lighting technology and understanding the new terms and units of measure can be the first step in lower energy costs.