What size socket is a standard bulb?
Most standard household bulbs in North America use an E26 Edison screw base, while Europe commonly uses an E27 base. The correct base depends on your region and the fixture you’re replacing.
Understanding base sizes
The base size refers to the thread diameter of the bulb in millimeters. The letter E stands for Edison screw, and the number indicates the approximate outer diameter of the threaded portion.
Common base sizes you may encounter
The following bases are the most frequently used in residential lighting. Knowing these sizes helps you buy bulbs that will physically fit your sockets.
- E26 — 26 mm diameter; standard in the United States and Canada for general household bulbs (A19, A21 shapes).
- E27 — 27 mm diameter; standard in most of Europe, parts of Asia, and other regions for general lighting (A60, LED equivalents).
- E12 — 12 mm diameter; a candelabra base common in chandeliers and small decorative lamps.
- E14 — 14 mm diameter; small Edison screw used in Europe for decorative lighting and some appliances.
- Bayonet B22d — 22 mm diameter bayonet base used in the UK and several Commonwealth countries; requires a bayonet-style socket.
Note: Some fixtures use non-Edison bases (such as GU-type twist-locks) or bayonet fittings. Always check the fixture label or the existing bulb to confirm the base type before purchasing.
Regional considerations and shopping tips
When servicing fixtures across regions, verify the base designation on the socket or on the bulb you’re replacing. If you need to switch base types, you may require adapters or a different fixture. Also pay attention to wattage and voltage ratings to ensure safety and performance.
Summary
The standard bulb base most people encounter is E26 in North America and E27 in Europe and many other regions. Smaller bases like E12 and E14 appear in chandeliers and compact fixtures, while bayonet bases (B22d) are common in the UK. Always confirm the socket type on the fixture and match it with the base size and wattage listed on the bulb packaging or the old bulb.
Are E26 and A19 the same?
No, E26 and A19 are not the same; they refer to different parts of a light bulb: E26 is the base size and type, while A19 is the bulb's shape and dimensions. All A19 bulbs in North America use an E26 base, but not all E26-based bulbs are A19 shaped—they can have other shapes, such as globe or candle styles.
E26: The bulb base
- Meaning: "E" stands for "Edison screw," and "26" indicates a 26-millimeter diameter for the base.
- Function: It's the threaded part that screws into a socket, connecting the bulb to the electrical current.
- Scope: E26 describes the base, so many different bulb shapes and sizes can have this base.
A19: The bulb shape
- Meaning: "A" stands for "arbitrary," a designation for the classic pear-like shape, and "19" refers to the bulb's widest diameter in eighths of an inch (19/819 / 819/8 inches, or about 2.3752.3752.375 inches).
- Function: It describes the bulb's physical form and maximum width, the standard shape for many household fixtures.
- Scope: This is a specific size and shape of a bulb, not the base it uses.
The connection
- An A19 bulb will always have an E26 base, making it compatible with any E26 socket.
- When you buy an "E26 bulb," it could be any shape, including an A19. It is crucial to check both the base and the shape to ensure it fits your fixture, especially if the fixture has size restrictions for the bulb's shape.
What size is a standard light bulb?
The standard light bulb size for household use in North America is the E26 base, a medium screw-in base with a diameter of 26 mm. In Europe and other regions, the similar E27 base is the standard, while smaller E12 bases are used for decorative fixtures like chandeliers and candelabras.
Common light bulb base sizes
- E26 (Standard): This is the most common size for general lighting in North America, found in standard household fixtures like lamps and ceiling lights.
- E27 (Standard): Used in Europe and other regions, it's very similar to the E26 but for different electrical standards.
- E12 (Candelabra): This smaller base is frequently used in decorative and candelabra fixtures, as well as night lights.
- E17 (Intermediate): A medium-small base often used for appliance bulbs and certain decorative or older Christmas lights.
- E39 (Mogul): A much larger base used for high-wattage applications such as streetlights and commercial fixtures.
What size is a standard bulb socket?
The standard bulb socket size in North America is the E26, which is also known as a "medium screw base". In Europe and other regions, the equivalent standard socket is the E27. These sizes are used for most household lighting, such as in lamps, ceiling lights, and vanity fixtures.
- E26 (North America): This is the most common socket for standard household bulbs, including incandescent, LED, and CFL types. The "E" stands for Edison, and the "26" refers to a diameter of 26 millimeters.
- E27 (Europe and other regions): This socket is equivalent to the E26 but is found in other parts of the world. The "27" refers to a diameter of 27 millimeters.
- Other common sizes: While E26 is standard, you may also encounter other sizes like the smaller E12 (candelabra) for decorative lights, and the larger E39 (mogul) for industrial fixtures.
Is the E26 a standard light socket?
E26 bulbs are some of the most common lamp types, meaning that finding an appropriate lampholder or fixture is typically quite straightforward. Additionally, installation is usually very straightforward, and requires no tools or assembly.
