Quick Answer

Different light bulb types (LED, CFL, halogen, incandescent) come in various sizes, shapes, and specifications. Understanding lumens (brightness), colour temperature, base types, and energy efficiency helps you select the perfect bulb for each space in your home.

Picking the right light bulb might seem simple, but stand in front of the lighting section at your local shop and suddenly there's a dazzling array of options. Watts, lumens, Kelvin ratings, CRI - it can all get a bit much! But getting it right matters, both for your electricity bill and for creating the perfect ambience in your home. 

So, in this guide, we'll shed some light on everything you need to know about light bulbs, helping you navigate through the options to find the perfect match for your home.

Key Takeaways

1. LEDs are now the standard, offering 90% energy savings over incandescents with lifespans up to 50,000 hours.
2. Match bulbs by fitting type first (B22d, E27, GU10), then consider lumens for brightness, not watts.
3. Choose appropriate colour temperatures: warm white (2700-3000K) for living areas and cool white (4000K) for task-oriented spaces.

What are the Different Types of Light Bulbs

The lighting industry has changed dramatically in recent years, particularly in the UK. With 98% of UK homes now using low-energy lighting (up from just 3% in 2001), understanding the different technologies is more important than ever.

Incandescent Bulbs

The original light bulb technology invented by Edison now belongs mostly in museums. These bulbs work by heating a tungsten filament until it glows, creating that warm, familiar light.

However, they're incredibly inefficient, converting just 5% of energy to light while wasting 95% as heat. Due to this inefficiency, traditional incandescent bulbs have been effectively phased out in the UK through energy efficiency regulations since 2018.

Halogen Bulbs

Halogen bulbs are essentially enhanced incandescents. They contain a small amount of halogen gas that allows the filament to burn hotter and brighter while lasting slightly longer than traditional incandescents.

Though marginally more efficient, these too are now largely unavailable for general lighting in the UK market. Under current regulations, most halogen bulbs don't meet minimum efficiency standards and have been discontinued. If you still have halogen fixtures, your best option is to replace them with LED equivalents.

CFLs (Compact Fluorescent Lamps)

These spiral or tubular bulbs were once the poster child for energy efficiency. They use electricity to excite mercury vapour, which produces ultraviolet light that then causes a phosphor coating to glow.

While CFLs use about 75% less energy than incandescent bulbs, they're rapidly becoming obsolete in the UK. Due to their mercury content, most CFL bulbs are being removed from the market under RoHS (Restriction of Hazardous Substances) regulations. By 2025, only special-purpose CFLs will remain available.

LEDs (Light Emitting Diodes)

LED (Light Emitting Diode) bulbs are the gold standard of modern lighting. These solid-state lamps use semiconductors to produce light when electricity passes through them.

LEDs offer remarkable efficiency, using up to 90% less energy than traditional incandescent bulbs. With a lifespan of up to 25-30 years (around 50,000 hours), they're the longest-lasting option available.

While slightly more expensive upfront, LEDs pay for themselves quickly through energy savings, often within months. They're versatile enough for any room and work well in cold temperatures, making them ideal for outdoor use too.

One thing to note: older dimmer switches might not work properly with LEDs, sometimes causing flickering.

Smart Bulbs

Smart bulbs combine LED technology with built-in connectivity features. Controllable via smartphone apps or voice commands, they offer convenience and customisation.

These bulbs provide the same efficiency benefits as standard LEDs but with added functionality like dimming, colour changing, and scheduling. The initial cost is higher, but the convenience and potential for further energy savings through automated control make them worth considering.

Bulb Type	Energy Efficiency	Average Lifespan	UK Availability	Best For
Incandescent	Very poor	1,000 hours	Phased out	N/A
Halogen	Poor	2,000 hours	Mostly phased out	N/A
CFL	Good	10,000 hours	Being phased out	Limited uses until fully removed
LED	Excellent	15,000-50,000 hours	Widely available	All general lighting needs
Smart LED	Excellent	15,000-25,000 hours	Widely available	Connected homes, flexible lighting needs

How to Identify Your Light Bulb Size

Finding the right size bulb starts with understanding the fitting code, the part that connects to your fixture. UK homes typically use several standard fittings, each with its own code.

The code consists of letters indicating the fitting type, followed by numbers showing the diameter in millimetres (or distance between pins for certain types).

Common UK Fittings

Bayonet Cap (BC) - B22d: The most common fitting in UK homes, measuring 22mm in diameter. It uses a push-and-twist motion to lock into the fitting. You'll find these in most ceiling lights and table lamps.

Small Bayonet Cap (SBC) - B15d: A smaller 15mm version, commonly used in smaller fixtures and decorative lighting.

Edison Screw (ES) - E27: Named after Thomas Edison, this 27mm screw cap is widely used throughout the UK, especially in newer fixtures.

Small Edison Screw (SES) - E14: A 14mm version typically used in chandeliers and smaller wall lights.

GU10: A mains-voltage fitting with two pins that twist to lock, commonly used in spotlights and downlights.

Always check the fitting type first before considering other factors like brightness or colour. No matter how perfect a bulb might be in other respects, it's useless if it doesn't fit your fixture!

Most Common Light Bulb Shapes (and Their Best Uses)

Light bulb shapes aren't just about aesthetics; they determine how light is distributed around your room.

GLS/A60 (Classic Pear Shape)

This is the iconic bulb shape most people picture when thinking of a light bulb. GLS (General Lighting Service) bulbs distribute light in all directions (nearly 360°), making them perfect for general room lighting through ceiling pendants and table lamps.

In UK packaging, you'll often see them labelled as A60, where "A" indicates the shape and "60" refers to the diameter in millimetres.

Globe (G45, G80, G125)

These perfectly round bulbs provide even, omnidirectional light similar to GLS bulbs. The number indicates the diameter in millimetres: G45 (golf ball size) for small fittings, G80 for medium fixtures, and G125 for statement pieces.

Globe bulbs are often used in open fixtures as decorative elements, particularly in bathroom vanities or modern pendant lights, where the bulb is visible.

Candle/Flame

Resembling a flame, these bulbs add elegance to chandeliers and decorative fittings. They provide a soft, ambient light and are designed to be seen. They're particularly common in dining rooms and formal living areas.

Spotlight and Reflector Bulbs

These include several subtypes:

GU10/MR16: Small, directional bulbs used in track lighting and recessed spotlights. They provide focused beams of light, ideal for highlighting specific areas or objects.

PAR (Parabolic Aluminised Reflector): These bulbs provide strong, directional light with precise beam control. They're used for accent lighting, security lighting, and outdoor floodlights.

R (Reflector): Similar to PAR bulbs but with a softer edge to the light beam. Common in recessed downlights in kitchens and bathrooms.

Tube Lights

These long, cylindrical bulbs are commonly used in kitchens, garages, and commercial spaces. LED tubes are now replacing traditional fluorescent tubes as the UK phases out mercury-containing lighting.

Shape	Best Uses	Typical Beam Spread	Common Bases
GLS/A60	General lighting, lamps	360°	B22d, E27
Globe	Decorative fixtures, vanities	360°	B22d, E27, E14
Candle	Chandeliers, sconces	360°	E14, B15d
R/PAR	Downlights, recessed lighting	15°-120°	GU10, E27
MR16	Accent lighting, track lights	15°-60°	GU5.3, GU10
Tube	Kitchen, office, utility areas	120°-180°	Various pin types

Key Light Bulb Specifications You Should Know

Understanding these essential specifications helps you choose the perfect bulb for every situation.

Luminous Flux (Lumens)

Lumens (lm) measure brightness; the higher the number, the brighter the light. This is the most important metric when choosing bulbs, rather than wattage.

As a rough guide:

• 400-450 lm: Equivalent to old 40W bulbs
• 700-800 lm: Equivalent to old 60W bulbs
• 1100-1300 lm: Equivalent to old 100W bulbs

Power (Watts)

Watts measure energy consumption, not brightness. Modern LED bulbs use far fewer watts for the same brightness. For example, a 10W LED can replace a 60W incandescent bulb while providing the same light output.

Efficacy (lm/W)

This tells you how efficiently a bulb converts electricity to light. Higher is better. UK regulations are pushing minimum efficacy to 120 lm/W by late 2023 and 140 lm/W by September 2027.

Colour Temperature (Kelvin)

Measured in Kelvin (K), this indicates light colour from warm yellow to cool blue:

• 2700-3000K: Warm white (cosy, relaxing)
• 3500-4000K: Cool white (clean, energetic)
• 5000-6500K: Daylight (bright, invigorating)

Colour Rendering (CRI/Ra)

The Colour Rendering Index measures how accurately a light source displays colours compared to natural sunlight. Higher is better, with 100 being perfect.

UK regulations require most general lighting to have a CRI ≥80. For colour-critical tasks like art, makeup, or design work, look for CRI ≥90.

Beam Angle

For directional bulbs, the beam angle determines the spread of light. Narrower angles (15-30°) create focused spotlights, while wider angles (60-120°) provide broader illumination.

Dimmability

Not all LED bulbs are dimmable, and those that are may not work with older dimmer switches. Always check compatibility before purchasing.

Choosing the Right Bulb for Each Room

Different spaces call for different lighting approaches. Here's a room-by-room guide:

Living Room

Create a warm, relaxing atmosphere with bulbs in the 2700-3000K range. Use a mix of ambient ceiling lights (800-1000 lumens) and softer table lamps (400-600 lumens). Dimmable options give flexibility for different activities.

A standard B22d LED GLS bulb with 800 lumens at 2700K creates the perfect ambience for evening relaxation.

Kitchen

Kitchens benefit from brighter, cooler lighting (3500-4000K) that makes food preparation safer and more pleasant. Consider higher lumen outputs (1100-1300) for main lighting, with directional spotlights over work areas.

GU10 spotlights with 35-60° beam angles ensure even illumination across worktops.

Bathroom

Combine general lighting (cool white 4000K) with task lighting around mirrors (90+ CRI for accurate colour rendering). Always check that fixtures are rated for bathroom use with appropriate IP ratings for wet zones.

Bedroom

Warm lighting (2700K) creates a restful environment. Consider dimmable options and multiple light sources, such as ceiling lights plus bedside lamps, for flexibility.

Home Office

Balanced lighting prevents eye strain. Choose bulbs around 4000K with high lumen output (1000+) and good colour rendering (CRI 90+) for comfortable, productive work.

Energy Efficiency & Lifespan Comparison

The UK has implemented strict energy efficiency standards for lighting. Since October 2021, all light bulbs must display the rescaled A-G energy label (no more A+, A++, etc.).

The government is pushing for even higher efficiency, with proposals to require light sources to achieve at least 120 lumens per watt (increasing to 140 lumens per watt from September 2027).

To put this in perspective, traditional incandescent bulbs produced about 15 lumens per watt, while modern LEDs typically deliver 90-120 lumens per watt.

These efficiency improvements translate to significant savings. The UK government estimates homeowners can save £2,000-£3,000 over a lifetime by switching to LED lighting.

In terms of lifespan:

• LED bulbs: 15,000-50,000 hours (15-30 years of typical use)
• CFL bulbs: 8,000-15,000 hours (8-10 years)
• Halogen bulbs: 2,000-4,000 hours (1-2 years)
• Incandescent bulbs: 750-2,000 hours (less than a year)

FAQs

What does "lumens" mean when choosing an LED bulb?

Lumens measure brightness, the higher the number, the brighter the light. When replacing old bulbs, match lumens rather than watts for equivalent brightness.

Can I use LED bulbs in any light fixture? 

Most fixtures accept LEDs, but some older dimmer switches may cause flickering. Always check compatibility, especially with enclosed fixtures, which can trap heat.

Why do my new LED bulbs flicker? 

Flickering usually indicates incompatibility with your dimmer switch or electrical system. Try a dimmer-compatible LED or replace your dimmer switch with an LED-rated version.

What's the difference between warm white and cool white? 

Warm white (2700-3000K) gives a cosy, yellowish glow like traditional bulbs. Cool white (4000K+) produces a brighter, cleaner light similar to daylight.

Do LEDs save money even if they cost more upfront? 

Absolutely. Though initially more expensive, LEDs typically pay for themselves within months through energy savings and can last 15-25 years before needing replacement.

How do I dispose of old light bulbs properly in the UK? 

LEDs and CFLs are considered electronic waste and should be recycled at household waste recycling centres or through retailer take-back schemes, not placed in general waste.

Why are fluorescent bulbs being phased out? 

They contain mercury, a hazardous substance. The UK is removing them from the market through RoHS regulations, with most general lighting fluorescents already unavailable.

Final Tip Before You Buy

Always start by matching the cap type and shape to your fixture, then consider light quality. For most homes, warm white LEDs (2700K) with CRI ≥80 create a comfortable environment, while kitchens and workspaces benefit from cooler temperatures (4000K).

For quality bulbs that meet all current UK standards and future efficiency requirements, browse our selection of LED lighting options. We've tested everything we sell in real-world conditions, so you'll get dependable performance without the guesswork.

Sources

1. https://www.gov.uk/
2. https://assets.publishing.service.gov.uk/
3. https://www.edie.net/
4. https://bregroup.com/