Why LED Light Is Measured In Lumens And Not Watts

Light Bulb GraphicThe emergence of energy-efficient LED light bulbs in the last few years has made choosing bulbs to replace your existing, wasteful incandescent bulbs a lot less simple than it used to be.

LEDs are at the forefront of current lighting technology and are developing and improving in efficiency. Unfortunately, this rapid development means that the traditional “Watt” measurement has become less and less able to accurately denote the brightness of a bulb.

For example, one manufacturer might proudly unveil their 4 Watt LED Bulb to replace a 30 Watt Incandescent bulb, only for it to be superseded a couple of months later by another, whose 4 Watt LED will replace a 60 Watt.

Thus, the lighting industry has now opted to use a more stable and widely-regarded unit for measuring the intensity of light, and that’s where Lumens enter the story.

So What Are Lumens?

In simple terms, Lumens (lm) are a measurement of the light that’s emitted by a lamp or bulb which is visible to the human eye. Therefore, the greater the number of Lumens, the brighter the light will appear.

Watts don’t necessarily measure the brightness of a bulb, only the amount of electricity it uses. People constantly make the mistake of believing that the number of watts denotes a bulb’s light output. But, as stated earlier, this is becoming a much less reliable indicator as time marches on.

Bulb Box/Bulb’s Packaging

The belief that a 100 watt bulb must be twice as bright as a 50 watt bulb has been our traditional purchasing criterion for many years, however, the reality of the situation is that the former merely sucks up more power than the latter and, in the case of LEDs vs Incandescent bulbs, for little or no payback.

When purchasing light bulb these days, always check out its Lumens.

The number will be displayed on the bulb’s packaging, as you’ll see from the picture of one of our bulbs.

So when you’re purchasing a light bulb, ask yourself whether you’re buying electricity or light, and if it’s light you’re after, go for the packaging that displays the greatest number of lumens, requiring the fewest number of watts.

This is what’s known as...

The Luminous Efficacy Of A Bulb

The effectiveness of a bulb can be expressed by its lumen-to-watt ratio or, in other words, the number of lumens it produces for each watt consumed.

The rate at which light bulbs convert watts into lumens varies considerably between different technologies. Bulbs that produce more lumens-per-watt are a great deal less expensive to run, as they generate more light for less power.

LEDs have the highest lumen-to-watt ratio of any type of lighting, which means they’re capable of producing a large amount of light for comparatively little energy. This is why one of our pictured Dimmable E27 Omni-LED Clear Globe Bulbs can produce the same 650 lumens of light as the 60 watt incandescent it’s designed to replace.

Longer-Lasting Energy-Saving

This massively reduced power requirement is literally “brilliant” for you as a buyer, because it not only means you’ll be getting a replacement light bulb that will cost you 90% less in terms of electricity, you’ll also benefit from the fact that LEDs have a considerably longer life-expectancy as well.

Producing a lot less detrimental heat than incandescent bulbs enables LEDs to achieve a 50,000 hour lifespan, so they’ll still be going strong in about 17 years’ time!

So, hopefully, the next time you’re searching for a replacement light bulb, you’ll buy one that’s brighter, longer-lasting and more energy-efficient, and that means you’ll be buying an LED!

If you’d like to see our full range of LED bulbs and LED lighting-related products, why not pop over to our LED lights online store.

And, should you require any help or further information about Lumens or, indeed, anything LED lighting-related, please don’t hesitate to contact a member of our customer service team on 0116 321 4120 or send an e-mail enquiry to cs@wled.co.uk.

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2 thoughts on “Why LED Light Is Measured In Lumens And Not Watts”

  • T Purcell

    There are some LED GU10 lamps on the market which use cd (candela) as the measure of output? How does this compare with lumens?

    Reply
    • admin

      Hello Trevor,

      The two measurements are very similar, but there are subtle differences. Lumens measure the total amount of "visible" light emitted from a source, i.e. its luminous flux. Candelas on the other hand measures the luminous intensity. Candelas are more commonly used in America, while lumens are more predominant in the EU.

      Hope this helps.

      Thom.

      Reply
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