How to Choose Light Bulbs UK 2026

Light bulbs used to be simple. 40, 60, or 100 watts. Screw-in or bayonet. Done. Now there are LEDs, lumens, Kelvin ratings, CRI scores, smart capabilities, and dimming compatibility. The choice feels overwhelming, but the fundamentals are straightforward once understood.

This guide explains how to choose the right bulbs for any fixture.

Why This Matters Now

The lighting world has shifted fundamentally:

Incandescent bulbs: Effectively gone. EU phased out in 2012, UK followed. Inefficient technology that produced more heat than light.

Halogen bulbs: Being phased out. September 2021 ban on most halogen shapes. Some specialist halogens remain briefly.

LED bulbs: Now the standard. 90% energy reduction, 25x lifespan, no heat waste. Initial high prices have fallen dramatically.

Smart bulbs: Growing rapidly. WiFi/Bluetooth connected, app controlled, colour changing, voice activated.

Understanding LEDs isn’t optional anymore - they’re what’s available. The good news: they’re better in almost every way.

The Essential Specifications

Lumens (Brightness)

Lumens measure light output - how bright the bulb actually is. This is what matters.

Watts measure energy consumption - how much electricity the bulb uses. Historically correlated with brightness for incandescents, but irrelevant for comparing different technologies.

The shift:

• Old thinking: “I need a 60W bulb”
• New thinking: “I need 800 lumens”

Lumen equivalents:

Old Incandescent	Lumens	LED Watts
25W	250	3-4W
40W	450	5-6W
60W	800	8-10W
75W	1,100	11-13W
100W	1,600	14-17W

When buying bulbs, ignore wattage except for energy costs. Focus on lumens for brightness.

Colour Temperature (Kelvin)

Colour temperature measures the warmth or coolness of light - not brightness, but hue. Measured in Kelvin (K).

The scale:

Kelvin	Description	Character	Best For
2200K	Extra warm	Candlelight, amber	Accent lighting, relaxation
2700K	Warm white	Traditional incandescent	Living rooms, bedrooms
3000K	Warm	Slightly brighter warmth	Throughout home, kitchens
4000K	Cool white	Bright, energising	Kitchens, bathrooms, offices
5000K	Daylight	Clinical, stark	Garages, workshops
6500K	Cool daylight	Blue-white	Task lighting, photography

Recommendations by room:

Room	Recommended Kelvin
Living room	2700K
Bedroom	2700K (or 2200K accent)
Kitchen (task)	4000K
Kitchen (dining)	3000K
Bathroom	3000-4000K
Home office	4000K
Hallway	2700-3000K

Key principle: Lower Kelvin = warmer/yellower. Higher Kelvin = cooler/bluer. Most homes suit 2700-3000K for living spaces.

CRI (Colour Rendering Index)

CRI measures how accurately colours appear under the light - how natural things look.

The scale: 0-100, with 100 being perfect (sunlight).

CRI Score	Quality	Suitable For
80-85	Good	General household
85-90	Very good	Living spaces
90-95	Excellent	Kitchens, bathrooms, art
95-100	Superior	Photography, colour-critical

Practical guidance:

• Minimum CRI 80 for all bulbs
• Prefer CRI 90+ for kitchens (food appearance)
• Prefer CRI 90+ for bathrooms (makeup application)
• CRI 95+ for artwork illumination

Why it matters: Low CRI makes food look unappetising, skin look sallow, and colours look dull. It’s the difference between lighting that feels right and lighting that feels off.

Bulb Fittings

Screw Fittings (Edison)

E27 (ES - Edison Screw):

• 27mm diameter
• Most common large fitting
• Standard table lamps, pendants
• Wide bulb selection

E14 (SES - Small Edison Screw):

• 14mm diameter
• Smaller fixtures, chandeliers
• Candle bulbs common
• Good selection available

Bayonet Fittings

B22 (BC - Bayonet Cap):

• 22mm diameter
• Traditional UK fitting
• Two pins, push and twist
• Common in older fixtures

B15 (SBC - Small Bayonet Cap):

• 15mm diameter
• Smaller bayonet
• Less common
• Some chandeliers and decorative

Pin Fittings

GU10:

• Two-pin twist-lock
• Spotlight/downlight standard
• Direct mains voltage
• Very common in UK homes

G9:

• Loop-pin fitting
• Compact, small fixtures
• Mains voltage
• Contemporary fixtures

G4:

• Two thin pins
• Low voltage (12V)
• Very small bulbs
• Some under-cabinet, display

GX53:

• Large disc shape
• Push-twist mount
• Under-cabinet, shallow fixtures

How to Identify Your Fitting

1. Remove existing bulb (power off first)
2. Measure diameter for screw fittings
3. Count pins and measure spacing for pin fittings
4. Check fixture documentation
5. Photograph and take to retailer if uncertain

Bulb Shapes

A60 (GLS - General Lamp Shape): Classic bulb shape. Most common for general use. E27 or B22 fitting typically.

Candle (C35): Decorative pointed shape. Chandeliers, wall lights. Usually E14 or B15.

Golf Ball (G45): Small round shape. Decorative, multiple bulb fixtures. E14 or E27.

Globe (G80, G95, G125): Large spherical. Statement pendants, exposed bulb fixtures. Numbers indicate diameter in mm.

Spotlight (GU10, MR16): Directional beam. Downlights, track lighting. GU10 most common.

Tube/Capsule: Small tubular. Compact fixtures. G9 or G4 fitting.

Filament Style: Decorative LED mimicking old Edison bulbs. Visible “filament” LEDs. Various shapes.

Dimming Compatibility

Why LEDs and Dimmers Conflict

Old dimmers (leading edge/TRIAC) were designed for incandescent bulbs that used significant power. LEDs use so little power that old dimmers can’t regulate them properly - causing flickering, buzzing, limited range, or failure.

Requirements for Dimmable LEDs

1. Bulb must be dimmable:

• Clearly marked “dimmable” on packaging
• Not all LEDs dim - many are on/off only
• Dimmable versions cost slightly more

2. Dimmer must be LED-compatible:

• Trailing edge dimmers (recommended)
• LED-specific dimmers
• Check minimum load rating (LEDs may be below old dimmer minimums)

3. Quality matters:

• Budget dimmable LEDs often dim poorly
• Name brands (Philips, Osram, Integral) more reliable
• Read reviews for specific dimmer/bulb combinations

Dimmer Types

Type	Suitable For	Notes
Leading edge (TRIAC)	Incandescent, halogen	Old standard, poor with LEDs
Trailing edge	LED, CFL	Modern standard, smooth dimming
Universal	All types	More expensive, most flexible
Smart dimmer	Smart bulbs	App/voice control, no physical bulb dimming

Troubleshooting Dimming Issues

Flickering at low levels:

• Dimmer minimum load too high for LED wattage
• Replace with LED-rated trailing edge dimmer

Buzzing sound:

• Incompatible dimmer type
• Poor quality bulb
• Try different dimmer or bulb brand

Limited dimming range:

• Dimmer not calibrated for LEDs
• Some dimmers have adjustment screws for range
• Try bulb from different manufacturer

Bulbs won’t turn on:

• Combined LED wattage below dimmer minimum
• Add more bulbs or change dimmer

Smart Bulbs

Types of Smart Bulbs

WiFi bulbs:

• Connect directly to home WiFi
• No hub required
• Can slow network with many bulbs
• Examples: TP-Link Tapo, LIFX

Zigbee bulbs:

• Require Zigbee hub (Hue Bridge, SmartThings)
• More reliable, less network congestion
• Better for large installations
• Examples: Philips Hue, IKEA TRADFRI

Bluetooth bulbs:

• Direct phone connection
• Limited range
• Simple setup
• Fewer features typically

Smart Bulb Features

Dimming: App control of brightness levels.

Colour temperature: Tune from warm to cool white.

Colour changing (RGB): Full colour spectrum (some models).

Scheduling: Automated on/off times.

Scenes: Preset configurations (Movie, Dinner, Morning).

Voice control: Works with Alexa, Google, Siri.

Away mode: Random on/off when away from home.

Best Smart Bulb Systems UK

Philips Hue:

• Market leader, widest ecosystem
• Excellent app, reliable system
• Premium pricing
• Requires Hue Bridge for full features

IKEA TRADFRI:

• Budget-friendly
• Decent quality
• Limited features vs Hue
• Good value proposition

TP-Link Tapo:

• No hub needed (WiFi)
• Very affordable
• Improving ecosystem
• Good entry point

LIFX:

• No hub needed
• Bright, vivid colours
• Premium quality
• Higher price point

Smart Bulb Considerations

Switches: Smart bulbs need constant power - traditional switches turn them “dumb.” Solutions:

• Leave switches on, use app/voice
• Smart switch covers
• Replace with smart switches

Cost: Smart bulbs cost significantly more than standard LEDs. Consider:

• How often will you use smart features?
• Is smart dimming worth 5x bulb cost?
• Would smart switches be more practical?

Obsolescence: Smart home platforms evolve. Choose established ecosystems.

Specialty Bulbs

Filament LEDs

What they are: LEDs designed to look like vintage Edison bulbs with visible “filament” elements.

Best for:

• Exposed bulb pendants
• Industrial/vintage aesthetics
• Decorative fixtures
• Ambient mood lighting

Considerations:

• Generally lower lumen output
• Often warmer colour temperatures (2200-2700K)
• More expensive than standard LEDs
• Make sure fixture suits exposed bulb

Reflector Bulbs

R63, R80 shapes: Reflector bulbs for specific fixtures, typically E27. Direct light forward.

GU10 spotlights: Built-in reflector for directional beam. Most common UK downlight fitting.

Beam angles:

• Narrow (15-25°): Accent lighting, highlighting
• Medium (35-45°): General downlight use
• Wide (60°+): Wash lighting, broad coverage

Coloured Bulbs

Permanent colour: Bulbs with coloured coating for specific applications.

RGB smart bulbs: Tuneable to any colour via app.

When to use: Accent lighting, parties, specific effects. Not for general illumination.

Making the Right Choice

Quick Selection Guide

If You Need…	Choose…
General room light	E27/B22, 800-1000lm, 2700K, CRI 80+
Kitchen task light	GU10 or E27, 4000K, CRI 90+
Bedroom ambient	E27/E14, 600-800lm, 2700K
Reading lamp	800lm+, 2700-3000K, dimmable
Chandelier	E14 candle, 400-600lm each, 2700K
Bathroom mirror	4000K, CRI 90+, IP rated if near water
Decorative exposed	Filament LED, 2200-2700K
Under cabinet	LED strip or G9/G4, 3000-4000K

Brand Recommendations

Premium quality:

• Philips
• Osram
• Integral LED

Good value:

• IKEA
• Energizer
• Crompton

Budget:

• Supermarket own-brand (variable quality)
• Amazon basics (adequate for non-critical use)

What to Check on Packaging

Essential information:

1. Lumens (brightness)
2. Kelvin (colour temperature)
3. Fitting type (E27, GU10, etc.)
4. Dimmable (yes/no)
5. CRI (if stated)
6. Lifespan (hours)

Nice to have:

• Energy rating
• Annual cost estimate
• Beam angle (for spots)
• Warm-up time

Common Mistakes

Buying by Watts

Problem: Choosing “60W equivalent” without checking lumens. Different brands interpret “equivalent” differently.

Solution: Always check lumens. 800lm = old 60W, regardless of what marketing claims.

Wrong Colour Temperature

Problem: Cool white (4000K+) in living spaces feels clinical and harsh.

Solution: Default to 2700K for living rooms and bedrooms. Reserve 4000K+ for task areas.

Ignoring CRI

Problem: Low CRI bulbs make everything look wrong, but the cause isn’t obvious.

Solution: Buy CRI 80+ minimum, CRI 90+ for kitchens and bathrooms.

Non-Dimmable with Dimmers

Problem: Installing non-dimmable LEDs in dimmer circuits causes flickering or failure.

Solution: Check packaging. If dimmer exists, buy dimmable bulbs.

Incompatible Dimmer

Problem: Using old TRIAC dimmer with LEDs causes buzzing, flickering, limited range.

Solution: Replace with trailing edge LED-compatible dimmer.

Enclosed Fixture Heat

Problem: LEDs in enclosed fixtures overheat, reducing lifespan dramatically.

Solution: Check bulb is rated for enclosed fixtures, or use fixtures with ventilation.

Our Recommendations

Best general-purpose LED: Philips LED A60 E27 - Reliable, good CRI, reasonable price.

Best dimmable: Integral LED E27 Dimmable - Smooth dimming, compatible with most dimmers.

Best GU10 spotlight: Aurora Enlite GU10 - Fire-rated option, quality light output.

Best filament style: Osram Vintage 1906 - Authentic appearance, quality construction.

Best budget: IKEA RYET - Surprisingly good for the price, limited options.

Best smart bulb: Philips Hue White Ambiance - Excellent app, reliable, tuneable temperature.

Best value smart: IKEA TRADFRI - Good ecosystem, fraction of Hue cost.

The Verdict

Light bulb technology has improved dramatically. LEDs last decades, use minimal energy, and offer unprecedented control over light quality. The complexity is real, but the fundamentals are simple:

Key principles:

• Buy by lumens, not watts
• 2700K for relaxation, 4000K for tasks
• CRI 80+ minimum, 90+ where colour matters
• Match dimmable bulbs with LED dimmers
• Quality brands for critical locations

The bulb in your lamp affects how your home looks, feels, and functions. Spend a few extra pounds on quality. The difference between adequate lighting and good lighting is often just the bulb.

Choose lumens. Choose temperature. Choose quality. Everything else follows.