Watts or Lumens?

With conventional light bulbs we used to choose the bulb by the Wattage. This is because there is little or no variation in the light output from old bulbs. For example - a 60w bulb always produced the same amount of light - around 800 lumens.

Lumens have come into everyday use largely as a result of the government mandate to phase out incandescent light bulbs in favour of CFL and LED bulbs. Because the old and new types of bulb consume very different amounts of energy to produce a given amount of light, lumens offer an easier way for consumers to compare the new LED lightbulbs with the old ones they are replacing.

The chart gives the approximate amount of lumens produced by conventional incandescent light bulbs.

LED lighting technology is constantly evolving, light bulbs are getting ever more efficient and we are getting higher lumens outputs for each watt of energy consumed. it is not accurate to simply state a 7w LED bulb is a direct replacement for an old 40w bulb, for example. It depends on the bulb. We need to look at the lumen output.

What are Lumens?
Lumens are a measure of the perceived power of visible light produced by a light bulb.

What are Watts?
Watts are a measure of power used by a light bulb. A watt is defined as the amount of power needed to move a one kilogram (2.2 pound) object at a speed of one meter per second against a force of one newton. In simple terms, it is a measure of the amount of energy something either uses or produces. One watt is equal to 1/746 horsepower.

What's the Difference?
A conventional light bulb and an LED light bulb may put out the same number of lumens, but the LED bulb will consume only approx 20% of the energy.