LED terms explained: the LED alphabet from A to Z

In short

• Brightness: look at lumens, not watts. Watts only tell you how much power the lamp uses.
• Light colour: Kelvin determines the colour. 2700 to 3000K is warm white, 4000K cool white, 6000 to 6500K daylight white.
• Indoors or outdoors: the IP rating tells you whether a lamp can handle dust and water. Outdoors, choose at least IP44 under a canopy and IP65 in the open air.
• Dimming: not every LED is dimmable, and not every dimmer suits every LED. Always check this on the product page.

Lumen

Lumen (lm) is the total amount of light a lamp gives off. An old 60-watt incandescent bulb gave about 800 lumens. An LED lamp achieves the same with roughly 8 to 10 watts. So when choosing, look at lumens, not watts. You can read more in What is a lumen? Lumens, watts and lux explained simply.

Lux

Lux is how much light falls on a surface, for example on your worktop. Lumen is about the lamp, lux about what arrives. For an office around 500 lux is common, for a workshop 300 to 500. See LED workshop lighting: how many lux and which lamps?.

Watt

Watt (W) is the power a lamp consumes. With LED the wattage is much lower than with old lamps for the same amount of light. So compare lamps on lumens and use watts to see how efficient they are.

Luminous flux

Another term for the total amount of light from a lamp, measured in lumens. More lumens means more light.

Luminous efficacy (lm/W)

How much light you get per watt, expressed in lumens per watt. The higher, the more efficient. An incandescent bulb manages just over 10 lm/W, good LEDs reach between 100 and 170 lm/W. That makes a difference on your energy bill, see LED vs incandescent, halogen and CFL: how much do you really save?.

Kelvin (colour temperature)

Kelvin (K) is the colour of the light. 2700 and 3000K are warm white: cosy and slightly yellow, ideal for the living room. 4000K is cool white: neutral and bright, handy for the office and workshop. 6000 to 6500K is daylight white: cool and bluish. Which colour suits where, you can read in Colour temperature LED: 2700K, 3000K, 4000K or 6500K?.

CCT (adjustable light colour)

With CCT (also tunable white) you set the light colour yourself, for example between 3000K, 4000K and 6000K. Handy if a room has several functions. You will find it in our LED panels and downlights and in the smart WiFi lamps.

CRI (Colour Rendering Index)

The CRI shows how true to life colours look under a lamp. 100 is daylight. CRI 80 or higher is fine at home, CRI 90 is great when colour matters, such as in the kitchen or bathroom.

Beam angle

The angle at which the light shines out of the lamp. A narrow beam angle (30°) gives a spot, handy for highlighting a painting. A wide beam angle (120°) lights up a whole room. You can read more about placing spots in Installing LED spots: recessed, surface-mounted and adjustable.

Flicker-free

A flicker-free lamp has a driver that keeps the light stable. You often cannot see flicker, but it can be tiring when working at a screen or on camera. Bothered by flickering or buzzing? Read Solving LED lighting problems.

Xenon white

A very bright, cool white of around 6000K, comparable to xenon car headlights. With us this is usually called daylight white.

Energy label

The energy label (A to G) shows how efficient a light source is. Since 2021 the scale has been reorganised, so a lamp that used to be A++ now often has a B or C. Read Energy label for lighting: what does it mean in 2026?.

E27 and E14

Screw fittings. E27 is the large fitting of the standard bulb, E14 the small fitting of candle bulbs. The E stands for Edison and the number for the diameter in millimetres. Take a look at the LED lighting for the bedroom for both types.

G9

A small fitting with two pins that you push straight into the socket. Widely used in decorative lamps and small fixtures. You will find them with the LED spots.

GU10

A fitting with two pins that you turn a quarter turn to click it in place, at 230V. This is the standard for ceiling spots.

MR16

A spot with a diameter of 2 inches (about 5 cm), often with a GU5.3 fitting and usually at 12V. Check that your transformer is suitable for LED.

Downlight

A lamp set into the ceiling that shines downwards. It gives even light without you seeing the lamp itself, for a sleek, modern look. Take a look at the LED panels and downlights.

Recessed (and surface-mounted)

Recessed means the lamp disappears into the ceiling, wall or floor. Surface-mounted sits on top instead, handy if you cannot or do not want to drill. The difference and the tips are in Installing LED spots.

Panel

A flat, square or rectangular LED lamp that gives very even light without shadows. Ideal for offices and modern interiors. Read LED panels for a home office or take a look at the LED panels.

LED tube (TL)

A long, thin lamp, in the past gas-filled and now LED. LED tubes use much less power and last much longer. You can read how to make the switch in Replacing fluorescent tubes with LED: step-by-step guide for every fixture.

High bay

A powerful pendant light for high spaces (from about 4 metres), such as halls and warehouses. Which fixture suits where is covered in Professional LED lighting for warehouses, offices and outdoor areas.

Tri-proof

A fixture that can withstand moisture, dust and impacts, usually rated IP65. Suitable for damp or dusty spaces such as the garage and basement. See Basement lighting: tips for damp spaces and Garage lighting.

Floodlight

A powerful lamp that lights a large area, for gardens, building sites, yards and sports fields. Our LED floodlights are much more efficient than old halogen floodlights. Tips on installing them are in Installing outdoor lighting.

Work light

A sturdy, bright lamp for the building site and for DIY jobs, often waterproof and shock-resistant. LED work lights are much more efficient than halogen and do not get as hot. Choosing between battery, 230V and hybrid? Read Choosing LED work lights.

Cabinet lighting

Lighting in or under cabinets, often with thin LED bars or small spots. Perfect for lighting a worktop or a display cabinet well. Take a look at the LED cabinet lighting.

Under-cabinet lighting

Lighting under your kitchen wall cabinets. It lights your worktop exactly where you need it. You use LED strips or LED bars for this, see also the LED lighting for the kitchen.

LED strip

A flexible strip of LEDs, which you can hang behind the TV, under cabinets or in a ceiling cove. There are COB strips for even light and RGB(W) strips for colour. You can read more in Indirect lighting with LED strips, or take a look at the LED strips.

Ceiling fan with light

A fan with built-in LED lighting. It cools and lights your room at the same time. Take a look at the LED ceiling fans.

Torch

A portable lamp running on batteries or a rechargeable pack. LED torches are brighter and last much longer than old torches. Take a look at the LED torches.

Emergency lighting

Lighting that comes on when the power fails. With LED it can run long and efficiently. Practical tips are in Emergency light for power cuts, or take a look at the LED emergency lights.

Flashing light

A lamp that flashes to attract attention, for example as a warning at roadworks or on vehicles. Take a look at the LED flashing lights.

Rotating beacon

A lamp with a rotating light effect, used on work vehicles and emergency services, among others. Take a look at the LED rotating beacons.

Ampere

The unit for electric current. Think of water in a garden hose: amperes are how much water flows through per second. With LED that is usually very little, because LEDs are efficient. It matters mainly when choosing a power supply or transformer.

Volt

The voltage of electricity. The wall socket delivers 230V. Some LEDs run on 12V or 24V, which is safer, especially outdoors. Then you need a driver or transformer.

Joule

A unit of energy. You rarely see it with LED, but it helps to know that for the same amount of light an LED needs much less energy than an old lamp.

Driver

The heart of an LED lamp. It makes sure the LED gets the right current. A good driver is decisive for lifespan and for flicker-free light.

Transformer

A device that changes the voltage, for example from 230V to 12V for MR16 spots and LED strips. With LED you need a suitable LED power supply, because old transformers often do not work well with it.

Heatsink

LEDs make heat too. A heatsink is a piece of metal that carries that heat away so the LED lasts long. You often see it as ribs on the lamp.

SMD (Surface Mounted Device)

Small LED chips mounted flat on a circuit board. You often see them as yellow squares in LED strips and lamps. The type, such as SMD2835, tells you something about the size of the chip.

COB (Chip on Board)

Many small LED chips packed close together on one surface. That gives a nicely even light without visible dots. COB strips are becoming more and more popular.

PWM (Pulse Width Modulation)

A technique for dimming LEDs. The lamp switches on and off at lightning speed, so fast that you cannot see it. The longer it is “on”, the brighter it appears.

RGB (and RGBW)

Red, green and blue. By mixing those colours the LED makes almost any colour. With RGBW a separate white LED is added for nicer white light. Fun for atmosphere, for example with the LED strips.

Quantum Dot

Minuscule particles that can refine the light of an LED, giving you nicer, purer colours. You mainly see it in screens and high-end LEDs.

UV LED

LEDs that produce ultraviolet light. You cannot see that light, but it is used for curing gel nail polish or for special effects. Be careful: UV can be harmful to your eyes and skin.

Hybrid LED

A lamp that runs on both mains power and a battery. Handy on the building site or in the garage, where there is not a socket everywhere.

Dimmable

If you can make the lamp softer or brighter, it is dimmable. Not all LED lamps can do this, and not every dimmer suits every LED. Always check this beforehand. You can read everything about dimmers and compatibility in Dimmable LED lighting: everything about dimmers and compatibility.

Leading edge

A dimming technique in which the start of each current wave is cut off. It works well with incandescent bulbs and halogen. Not all LEDs cope well with it, so check this with dimmable LEDs.

Trailing edge

A dimming technique in which the end of each current wave is cut off. For LED this is usually the best choice: less flicker and less humming. Modern dimmers often use this technique.

Warm dimming

The light gets warmer and more orange as you dim, just like with an old incandescent bulb. Very atmospheric in the living room. Not every dimmable LED can do this.

Motion sensor

A sensor that notices when someone is nearby and then switches the light on. Handy in the garage, the garden or the bathroom. It saves power and you no longer have to search for the switch. Read LED lighting with a sensor.

Dusk sensor

A sensor that measures how much daylight there is. When it gets dark the lamp comes on, when it gets light it goes off. Handy for outdoor lighting.

Smart LED

LEDs that you control with your phone or your voice. You set colour, brightness and schedules. Take a look at the LED WiFi lamps and read the LED trends 2026.

Linkable

Lamps that you can connect to each other, such as fixtures, LED strips or string lights. You then need only one connection point. Watch the maximum number you may link.

Solar LED

LED lighting powered by solar energy. Handy for the garden, with no power cable. You can read whether it pays off in Solar LED outdoor lighting: when does it pay off and when not?.

IP rating

This number shows whether a lamp can handle dust and water. IP20 is for indoors. IP44 can handle splashing water, for example in the bathroom. IP65 is dust-tight and can handle water jets: garden and building site. IP68 can even go under water. It is all explained in IP rating explained: IP20, IP44, IP65 and IK08.

Waterproof

Always check the IP rating instead of relying on the word “waterproof” alone. Under a canopy you can get by with IP44, in the open air choose at least IP65. See Installing outdoor lighting and Choosing LED work lights.

Lifespan

How long an LED lasts, usually 25,000 to 50,000 burning hours. At 4 hours a day that is roughly 17 to 34 years. That is why many of our LEDs come with a 5-year warranty.

Switching cycles

How often you can switch a lamp on and off. LEDs are hardly affected by this, unlike old energy-saving bulbs. Useful with sensors that switch the lamp often.

Warm-up time

How long it takes before a lamp burns at full strength. LEDs are bright immediately, with no waiting like old energy-saving bulbs.

Lighting zones

Dividing lighting smartly into zones: task light in the kitchen, mood light in the living room and reading light by your chair. See lighting by room for inspiration.

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