LED Light Bulb basics - a helpful guide
Kelvin = Colour Temprature
Kelvin measures colour temperature—the hue of light emitted from a bulb—and is entirely separate from brightness. Lower kelvin values produce warmer, orange-toned light; higher values produce cooler, blue-toned light.
With older incandescent bulbs, dimming would lower the kelvin value and shift the colour warmer. Modern LED bulbs behave differently; dimming typically does not alter their colour temperature in the same way.
The most common kelvin values you'll encounter are 2700K (warm white), 3000K (warm white), and 4000K (neutral white). See the examples in the image above to compare how each appears.
There is no universal standard for categorising warm, neutral, and cool light. However, at Dusk Lighting we categorise as follows:
* Below 2700K – Extra Warm White
* 2700K to 3000K – Warm white
* 4000K – Neutral White
* Above 4000K – Cool White
CCT= Colour Changing Temperature- which means you can change the Kelvin on the bulb or fitting. This is different from RGB which is is the whole colour spectrum.
Lumen = Brightness
Lumens measure the total amount of visible light emitted by a bulb, regardless of the light source. It's the key metric for understanding brightness.
A common benchmark: 806 lumens is equivalent to the brightness of a traditional 60W incandescent bulb. Around 480 lumens approximates a 40W incandescent bulb. This makes it easy to compare modern LED and energy-efficient bulbs to the familiar incandescent standard you may already know.
Why lumens matter more than watts: Watts measure energy consumption, not brightness. Two bulbs can use the same wattage but produce very different light output. Lumens tell you what you actually get—the brightness you'll see in your space.
When choosing bulbs for your fixtures, look for the lumen count that matches your needs. For ambient lighting in living areas, 800–1000 lumens works well. Task lighting or accent pieces may need more or less depending on the effect you're creating.
Tip: If you have a dimmer switch installed, opt for higher lumen bulbs. This gives you the flexibility to dial down brightness to your preferred level while maintaining quality light output across the full range of dimming.
Wattage = Power Input
Low wattage LED bulbs deliver the same brightness as high wattage incandescent bulbs while using a fraction of the energy. An LED bulb consuming just 6 watts can produce light equivalent to a 60 watt incandescent, and a 11 watt LED matches a 100 watt incandescent. This dramatic difference exists because LEDs convert energy into light far more efficiently, whereas incandescent bulbs waste most of their energy as heat. When selecting lighting for your home, comparing wattage directly between LED and incandescent is misleading — instead, look at lumens, which measure actual brightness output. A lower watt LED will illuminate your space just as effectively as a higher watt incandescent while reducing your energy consumption and electricity costs significantly.
Do not confuse wattage with brightness, thats in the past!
ALWAYS CHECK THE MAX WATTAGE ON A FITTING TO ENSURE SAFETY AND COMPATIBILITY!
Dimmable? Not all are!
Not all LED bulbs are dimmable, and it's important to check before purchasing. A dimmable LED bulb will work perfectly on a standard on/off switch, functioning just like a regular bulb. However, a non-dimmable LED bulb cannot be used on a dimmer switch, as it may flicker, fail to dim properly, or be damaged.
When selecting bulbs for your fixtures, always verify the dimmability to ensure compatibility with your switch type. This simple check will help you avoid compatibility issues and get the most from your lighting investment.
Ensure your dimmer switch is LED compatible!
Bulb Sockets - The Most Common UK & European types
E27
E27, commonly known as the Edison screw, is the standard socket type across modern UK and EU light fittings. It has largely superseded the B22 bayonet fitting that was once prevalent in British homes, making it the go-to choice for contemporary lighting installations. It can vary in lumen output from a low 150 up to 2000 lumens.
E14
E14 is the smaller version of the E27 base, commonly used in multi-armed pendant lights and wall lights. These bulbs deliver varying brightness levels depending on the wattage and technology — LED E14 bulbs typically range from 300 to 600 lumens, making them ideal for accent lighting and decorative fixtures where you want controlled, focused illumination rather than room-wide brightness.
B22
B22s are a traditional British design that is slowly being phased out in favour of E27 bulbs in modern fittings, aligning with European market standards. Screw-in bulbs are also considered safer than push-and-twist designs.
GU10
GU10 are common lamp types designed for focusing light and are commonly found in downlights, but can also be used in pendant, wall, table and floor lamps. Lumens typically range from 350 to 600.
G9
G9 capsules are often used in small light fitting designs where space is at a premium. They're ideal for bathroom wall lights and large chandeliers where the bulb needs to be discreet. These bulbs typically range from around 150 to 500 lumens, depending on the specific model.
G4
G4 bulbs are not as common as they once were, as modern lighting has increasingly incorporated G9 alternatives. However, they remain in use in kitchen and bathroom cupboards and other small household appliances.
Filament or non-filament, that is the question!
Filament Bulbs = are simply bulbs where you can see LED filaments inside. These are generally more aesthetically pleasing and more traditional in appearance. Often used where the bulb is visible, filament bulbs can create a striking focal point. If you have a bare filament bulb in a fitting, it can sometimes feel stark and uncomfortable on the eye when illuminated, so choose wisely. Consider dimming functionality if installing in a bedroom, lounge or kitchen for added comfort and ambience.
Non-Filament = These tend to be more opal, opaque or milky in appearance. These can be less visually striking, but are excellent for softening the harshness of emitted light. We recommend that these should be used in fittings that have fabric shades or where bulbs are not visible. They add a layer of diffused light and are often cheaper than the filament alternative.
Note: Filament and non-filament bulbs can come in a range of different sizes, socket types etc
Bulb Shape - A Rough Guide
Bulb shape significantly impacts the look of your lighting. The great news is you can change it affordably whenever you like. Always check the bulb dimensions against your fitting or shade to ensure a proper fit. While bulbs have technical codes, we use everyday names here for simplicity. We're focusing on the most common shapes, though novelty options are available.
1. GLS – The most common shape you'll see. A traditional classic that works in most standard fittings.
2. Pear – A vintage-inspired design that's become increasingly popular for decorative and ambient lighting.
3. Candle – Ideal for narrow fittings, chandeliers, and wall sconces where a slender profile is needed.
4. Golf Ball – A compact, spherical bulb perfect for recessed fittings or where you want the bulb hidden from view.
5. Globe – Available in various sizes, this rounded shape offers a softer aesthetic than GLS, especially suited to pendant lights.
6. Small Tube – A compact linear option for specific fixture types and tight spaces.
7. Large Tube – Longer linear bulbs that work well in under-cabinet or architectural applications. Always verify length compatibility with your fitting.
8. GU10 – Technically a socket type, but commonly referred to by shape. Features a push-and-twist fitting.
9. Capsule – Tiny, concentrated bulbs often called G9 or G4, named after their socket types. Perfect for accent lighting and compact fixtures.
