Choosing a replacement light bulb might seem simple, but with several different types of bulb bases available, it's not always obvious which one you need.
You may have seen codes such as E27, E14, GU10, G9 or B22 when searching for LED light bulbs. These letters and numbers identify the type of base or cap on a bulb, helping you select the correct replacement for your lamp holder.
Across Europe, Edison Screw bases such as E27 and E14 are particularly common, while GU10 and G9 are frequently used in spotlights and decorative lighting. Understanding the differences can save time, prevent ordering mistakes and help you choose the right LED bulb.
In this guide, Zico Lighting explains the most common light bulb base types, how to recognise them and what to look for when purchasing a replacement.
What Is a Light Bulb Base or Cap?
The base, sometimes called the cap, is the part of a light bulb that connects to the lamp holder.
Different bulb bases use different connection methods. Some screw into place, others use a twist-and-lock mechanism, while certain compact bulbs simply push into their sockets.
The letters and numbers used to identify a bulb base aren't random. They describe the type of connection and, in many cases, its dimensions.
For example:
- E27: Edison Screw base with a nominal diameter of 27 mm.
- E14: Edison Screw base with a nominal diameter of 14 mm.
- GU10: Twist-and-lock base with pins spaced 10 mm apart.
- G9: Compact push-in base with contacts spaced 9 mm apart.
- B22: Bayonet cap with a nominal diameter of 22 mm.
Knowing these codes makes it much easier to identify the correct replacement bulb.
What Are the Most Common Light Bulb Bases in Europe?
Although there are many different bulb bases available, the following are among the most recognisable types used in residential, hospitality and commercial lighting.
| Bulb Base | Connection Type | Common Uses |
|---|---|---|
| E27 | Large Edison Screw | Pendant lights, table lamps, ceiling lights and decorative lighting |
| E14 | Small Edison Screw | Chandeliers, wall lights, candle bulbs and smaller lamps |
| GU10 | Twist-and-lock | Spotlights, recessed downlights and accent lighting |
| G9 | Push-in capsule | Decorative wall lights, chandeliers and compact lamps |
| B22 | Bayonet | Traditional lamps and certain older or imported light fixtures |
Let's take a closer look at how to identify each one.
E27 – The Large Edison Screw Bulb Base
The E27 is one of the most widely used light bulb bases across continental Europe.
It features a metal screw thread with a nominal diameter of 27 mm, allowing the bulb to screw directly into a matching lamp holder.
The letter E stands for Edison Screw, while 27 refers to the diameter of the base in millimetres.
Where Are E27 Bulbs Commonly Used?
E27 bases are frequently found in:
- Pendant lights and ceiling lamps
- Table lamps and floor lamps
- Decorative exposed-bulb lighting
- Residential and commercial interiors
- Restaurants, hotels and hospitality environments
One of the advantages of E27 is its versatility. It is available on a wide variety of LED bulb shapes, including traditional round bulbs, globes, decorative filament lamps and oversized statement bulbs.
How to Identify an E27 Bulb
Look for a relatively wide metal screw base with a continuous threaded surface.
If you're unsure whether your bulb is E27 or E14, compare the diameter of the screw base. E27 is noticeably wider.
Quick identification: E27 = Large Edison Screw, 27 mm diameter.
E14 – The Small Edison Screw Bulb Base
The E14 is another popular bulb base throughout Europe, particularly for decorative and smaller-scale lighting.
Like E27, it uses a screw connection, but the threaded base is significantly narrower, measuring approximately 14 mm in diameter.
E14 is sometimes referred to as the Small Edison Screw (SES).
Where Are E14 Bulbs Commonly Used?
E14 bases are often found in:
- Chandeliers and decorative ceiling lights
- Wall-mounted lamps
- Bedside and table lamps
- Candle-shaped LED bulbs
- Smaller decorative light fixtures
Because the base is compact, E14 bulbs are particularly suitable for elegant lighting designs where the bulb needs to complement the overall appearance of the lamp.
How to Identify an E14 Bulb
An E14 bulb has a narrow metal screw base, similar in appearance to E27 but considerably smaller.
If your existing bulb has a screw base measuring approximately 14 mm across, it is likely to be an E14.
Quick identification: E14 = Small Edison Screw, 14 mm diameter.
E27 vs E14 – What's the Difference?
E27 and E14 are both Edison Screw bases, but they are not interchangeable.
The main difference is the diameter of the threaded base.
| Feature | E27 | E14 |
|---|---|---|
| Base type | Edison Screw | Edison Screw |
| Base diameter | 27 mm | 14 mm |
| Common name | Large Edison Screw | Small Edison Screw |
| Typical applications | Pendants, ceiling lights, table lamps | Chandeliers, wall lights, decorative lamps |
An E27 bulb will not screw directly into an E14 lamp holder, and an E14 bulb will not securely connect to an E27 lamp holder.
When replacing a bulb, always check the base size rather than assuming that a similar-looking bulb will be compatible.
GU10 – The Twist-and-Lock Bulb Base
GU10 is one of the most recognisable bulb bases used for spotlights.
Unlike Edison Screw bulbs, GU10 bulbs do not have a threaded base. Instead, they feature two short pins with wider ends that secure into a matching lamp holder using a twist-and-lock action.
The two pin centres are spaced 10 mm apart.
Where Are GU10 Bulbs Commonly Used?
GU10 LED bulbs are commonly used in:
- Kitchen spotlights
- Recessed ceiling downlights
- Living room accent lighting
- Retail and display lighting
- Hotels, restaurants and commercial interiors
GU10 spotlights are particularly popular for directional lighting, allowing light to be focused on specific areas, surfaces or architectural features.
How to Identify a GU10 Bulb
Turn the bulb over and examine the base.
A GU10 has two short pins with enlarged ends, rather than a screw thread or straight push-in contacts.
To remove a GU10 bulb, it normally needs to be gently twisted before being withdrawn from the lamp holder.
Quick identification: GU10 = Two short, enlarged pins with a twist-and-lock connection.
G9 – The Compact Push-In Bulb Base
G9 bulbs are small capsule-style lamps commonly used in decorative lighting.
Instead of a screw or twist-and-lock base, G9 bulbs have two loop-shaped metal contacts that push directly into a matching lamp holder.
The contacts have a nominal spacing of 9 mm.
Where Are G9 Bulbs Commonly Used?
G9 bulbs are often found in:
- Decorative wall lights
- Chandeliers
- Contemporary ceiling lamps
- Compact table lamps
- Feature and accent lighting
Their compact size makes them particularly useful where the light source needs to fit within a smaller decorative design.
How to Identify a G9 Bulb
Look for two small loop-shaped wire contacts at the bottom of the bulb.
Unlike GU10 bulbs, G9 bulbs do not twist into place. They use a push-in connection.
Quick identification: G9 = Compact capsule bulb with two loop-shaped contacts.
B22 – The Bayonet Bulb Cap
The B22 is a traditional bayonet-style bulb cap.
Although Edison Screw bases are more widespread across continental Europe, B22 bulbs may still be encountered in older installations, imported lamps and certain European markets.
The B22 cap has a nominal diameter of 22 mm and features two small pins positioned on opposite sides of the metal base.
Where Are B22 Bulbs Commonly Used?
B22 caps may be found in:
- Traditional ceiling lights
- Table lamps
- Older residential lighting installations
- Certain imported decorative lamps
How to Identify a B22 Bulb
A B22 bulb has a smooth cylindrical metal cap with two small pins protruding from its sides.
Rather than screwing into place, the bulb is pushed into the lamp holder and turned to lock it securely.
Quick identification: B22 = Bayonet cap, 22 mm diameter, with two side pins.
How to Identify Which Light Bulb Base You Need
If you're unsure which bulb base your lamp requires, there are several simple ways to find out.
1. Check Your Existing Light Bulb
Start by switching off the light and allowing the bulb to cool completely before removing it.
Examine the base for printed markings. Many bulbs have their base type printed on the body or metal cap.
Look for codes such as E27, E14, GU10, G9 or B22.
2. Look at the Shape of the Base
The connection method can often help you identify the bulb.
- Screw thread: Usually E27 or E14.
- Two short pins with enlarged ends: Usually GU10.
- Two loop-shaped wire contacts: Usually G9.
- Smooth metal cap with two side pins: Usually B22.
3. Measure the Base
If there are no visible markings, measuring the base can help.
For Edison Screw bulbs, measure the approximate diameter of the threaded metal section.
An E27 base measures around 27 mm, while an E14 measures around 14 mm.
For other bulb bases, compare the connection design and dimensions with the manufacturer's specifications.
4. Check the Lamp Holder
Sometimes the lamp holder itself will have a printed or moulded identification code.
This can be particularly helpful if the original bulb is missing or its markings have worn away.
5. Compare With Product Images
If you're still unsure, compare your existing bulb base with clear photographs of the different types.
Pay particular attention to the connection rather than the overall shape of the bulb.
Does the Shape of a Light Bulb Determine Its Base?
No. This is one of the most common misunderstandings when choosing replacement bulbs.
A light bulb's shape and its base are two separate characteristics.
For example, an LED candle bulb may be available with either an E14 or E27 base. Similarly, decorative globe bulbs can be produced with different screw bases.
This means you cannot reliably identify a bulb's base simply by looking at its overall shape.
When selecting a replacement, always check both:
- The bulb base: To ensure it connects correctly to your lamp holder.
- The bulb shape and dimensions: To ensure it suits the design and available space.
This is particularly important for decorative lighting, where the appearance of the bulb is often an important part of the overall design.
What Else Should You Consider When Choosing an LED Bulb?
Once you've identified the correct base, there are a few other features worth considering to achieve the lighting effect you want.
Bulb Shape and Size
LED bulbs are available in a wide variety of shapes, including traditional round bulbs, candle bulbs, globes, spotlights and decorative filament designs.
Check the bulb's dimensions to ensure it suits your lamp and complements the overall design.
Brightness
Brightness is measured in lumens.
When choosing a replacement LED bulb, consider how much light you need rather than simply matching the wattage of your previous bulb.
Colour Temperature
Colour temperature describes how warm or cool the light appears and is measured in Kelvin (K).
Warm white lighting, such as 2700K, is popular in homes, hotels and restaurants, while warmer tones such as 2400K can create a particularly soft, inviting atmosphere.
Colour Rendering
Colour Rendering Index (CRI) describes how accurately a light source reveals colours compared with a reference light source.
High-quality LED lighting with a CRI of 95+ can be particularly beneficial in interior design, retail and hospitality environments where accurate colour appearance matters.
Dimming Performance
If your lamp is controlled by a dimmer, make sure the LED bulb is designed to be dimmable and is compatible with the dimming system.
Choosing a suitable LED bulb can help achieve smooth, comfortable dimming without unwanted flicker.
Frequently Asked Questions About Light Bulb Bases
What Is the Most Common Light Bulb Base in Europe?
E27 is one of the most widely used bulb bases across continental Europe, particularly for general household and decorative lighting. E14 is also extremely common, especially in smaller lamps and chandeliers.
How Do I Know Whether My Bulb Is E27 or E14?
Both have metal screw threads, but E27 has a nominal diameter of 27 mm, while E14 measures 14 mm.
The easiest way to tell them apart is to compare or measure the width of the threaded base.
Can I Replace an E14 Bulb With an E27 Bulb?
Not directly. E14 and E27 have different base diameters and require corresponding lamp holders.
Choose a replacement bulb with the same base designation as your existing bulb.
What Does GU10 Mean?
GU10 identifies a twist-and-lock bulb base with two short, enlarged pins spaced 10 mm apart.
It is commonly used for LED spotlights and directional lighting.
What Is the Difference Between GU10 and G9?
GU10 bulbs have two short pins with enlarged ends and use a twist-and-lock connection.
G9 bulbs have two loop-shaped wire contacts and use a push-in connection.
They are designed for different lamp holders and are not interchangeable.
Is B22 the Same as E27?
No. B22 is a bayonet cap that uses two side pins, while E27 is a threaded Edison Screw base.
Although the bases may appear similar in size, they connect to lamp holders differently.
Can Two Bulbs With the Same Base Have Different Shapes?
Yes. The base type identifies how the bulb connects to the lamp holder, not the overall shape of the bulb.
For example, E27 LED bulbs can be available in traditional, globe and decorative filament styles.
Can I Change to an LED Bulb Without Changing My Lamp?
In many cases, yes. LED bulbs are available with common bases such as E27, E14, GU10, G9 and B22.
Check that the replacement has the correct base, suitable dimensions and appropriate compatibility with your lamp and controls.
Find the Right LED Bulb Base With Zico Lighting
Understanding light bulb bases makes it easier to choose the correct replacement and explore the wide variety of LED lighting options available.
Whether you're looking for an E27 decorative globe, an E14 candle bulb, a GU10 spotlight or a compact G9 lamp, identifying the correct base is the first step.
At Zico Lighting, we specialise in high-quality LED lighting designed to combine beautiful illumination with reliable performance. Our range offers a variety of bulb shapes, bases, finishes and colour temperatures to suit residential, hospitality and commercial interiors.
Explore the Zico Lighting EU collection to discover LED bulbs for your next lighting project.
Still unsure which light bulb base you need? Contact our team for advice on selecting the right LED bulb for your lamp.