As LED technology becomes ever more advanced and the bulbs themselves better and more affordable, it will become increasingly important to know all the lingo.  That’s why we at LED Monkey HQ want you to be as well informed about all the terms that relate to it. So, read on for 10 of the most important terms you’ll need to know…


For many years, we’ve measured the brightness of our light bulbs using Watts, when we should’ve been using Lumens all along!

Indeed, Watts are a measurement of energy consumption while Lumens are an indication of how bright a bulb is.

Lumen Diagram

The higher the number of Lumens on the packaging of your LED bulb, the brighter it will be. For maximum efficiency, it’s imperative that you opt for an LED bulb that emits the highest number of Lumens for the smallest number of Watts expended to achieve them.

Luminous Efficacy

Luminous Efficacy is a measure of how well a light source like an LED bulb produces visible light.

It’s measured in Lumens per Watt (l/w) in the International System of Units (SI); LED light bulbs giving up to 100 Lumens per Watt, compared to an incandescent bulb that will only generate 12 to 17 l/w.

This is excellent news for anyone who’s replacing their old incandescent light bulbs with energy-saving LEDs. It means you’ll get just as much light for a lot less power, saving a whole lot of money in the process!


“Watts” refers to the amount of power consumed and the rate at which energy draws from an electrical system. Light bulbs such as incandescents with a high w/lm (Watt to Lumen) ratio consume a large amount of energy.

However, LEDs run on around 10% of the power of an equally bright incandescent bulb. This means they’re a lot more energy-efficient and cost-effective.


Danger High Voltage Sign

“Volts” are the standard measurement of electrical potential, and they're generated by forcing an electrical current through a conductor.

The majority of our household bulbs operate at a mains voltage of between 230 and 240V.

Colour Temperature

“Colour Temperature” is the colour of the light produced by a bulb as it is perceived by the human eye. It’s quantified in degrees Kelvin (K), which is normally a measure of physical heat.

A simple way to remember about colour temperatures is - the lower the colour temperature number, the more relaxing and cosy the light. The higher the number, the brighter and more clinical the light.

All the different LED colour temperatures

The lighting industry is yet to lay down a hard-and-fast rule about exactly which number corresponds with which colour mode. However, our LED bulbs come in three colour temperatures.

Each of them will enable you to modify the ambience of your room according to its function and your taste. As such:

  • 2700 – 3000K Warm White is the most popular choice for lounges and bedrooms. It provides a mellow, relaxing glow that’s similar to that of an old incandescent bulb.
  • 3700 – 4000K Daylight provides an extremely accurate approximation of natural daylight. This makes it the ideal choice for both home office spaces and classrooms.
  • 6000K Cool White is best suited to work-related activity areas. This includes rooms such as the bathroom and the kitchen, given its penetrative brightness.

One room, three LED colour temperatures

Beam Angle

While incandescent light bulbs ruled the roost, lighting beam angles were never really considered important, however, today’s LED light bulbs are extremely specialised and allow you to choose just the right one to achieve exactly the right effect.

An MR16 LED Spotlight Bulb

For example, certain of our LED MR16 (pictured left) and LED GU10 Spotlight Bulbs are highly directional. They will focus their beams on a particular ‘spot’ within a 35 – 60° area. This makes them excellent choices for display cabinets, where they’ll pick out individual items perfectly.

Please see the infographic below as it illustrates the different beam angles on an MR16 spotlight bulb.

MR16 Beam Angle Infographic

Colour Rendering Index (CRI)

Colour Rendering Index Diagram

The CRI of an LED bulb lets us know how effectively it simulates natural daylight. As you'll see in the image above, objects perceived by the light of a high CRI LED will seem brighter and more vivid to the viewer.

As LED technology continues to progress in leaps and bounds, LEDs with a CRI of 80 or above will become more and more commonplace. Eventually, they will mimic daylight perfectly when they reach 99 or 100.


A luminaire is a light fitting that has an LED bulb contained within it. Luminaires are different from regular light fittings in that they’re all-in-one units with an integral light source (bulb), such as an industrial bulkhead light or a domestic floodlight.

Generally, manufacturers build luminaires with robustness and longevity in mind.  That's because, when the bulb’s luminous efficacy declines, it’s necessary to purchase a completely new lighting unit.


The 4 main LED bulb bases

The Fitting is the section of the LED bulb that’s connected directly to the appliance and thence to the mains power supply. There are quite a few to choose from and their main function is to make it as easy as possible for you to uncouple and replace the bulb when it needs replacing.

Life Hours

“Life Hours” denote the length of time you can expect a light bulb to last. It can be found both in the product's specification table on our website, and on our bulb packaging, too.

To calculate old-fashioned incandescent bulbs' life hours, a group of samples were observed until the point at which 50% began to burn out.

We calculate LED life hours differently, because they wind down slowly rather than fizzle out or pop.

LEDs’ “Lumen Maintenance” is, instead, decided over a pre-set period of time. It’s clear that they outlast traditional incandescent bulbs as many as 20 times over. Indeed, with a life-expectancy in the region of 50,000 hours, you can expect them to still be glowing strong in over 17 years!

Ask Us Anything!

If you’d like some more information or guidance about switching to LED lighting, please don’t hesitate to get in touch.

You can call one of our customer service advisors on 0800 999 7797. Or, you can always ping us an e-mail to:

You’ll also find us on Facebook, Twitter and Instagram, so leave a comment or a tweet anytime! We aim to reply to any social media comments or queries within 24 hours. And, if you're having any LED-related difficulties, take a look at our excellent FAQs page.