Light Bulb Codes: Shape, Size & Bulb Type (2024)

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Light Bulb Codes: Shape, Size & Bulb Type? ›

Definitions of bulb-shaped. adjective. shaped like a bulb. synonyms: bulblike, bulbous circular, round. having a circular shape.

Definitions of bulb-shaped. adjective. shaped like a bulb. synonyms: bulblike, bulbous circular, round. having a circular shape.

Bulb Shape/Type determines how the light is distributed. Every bulb shape has a recommended usage or fixture to be used in. For example, flood-type bulbs are best for recessed ceiling fixtures; standard light bulbs for desk and floor lamps. Bulb Base determines how the bulb screws or plugs into a socket.

What is an A19 Bulb? The most common type of bulb used in homes today is the A19. It gets its name because it has a rounded pear shape (an "A"—or arbitrary—shape) and its base measures 19 mm across. It has a medium-sized screw mount that fits into a standard socket.

Every type has unique characteristics represented by a letter, or series of letters, and a number, referred to as light bulb codes. These codes are located on the packaging and will help you determine if the bulb is the right type for your fixture.

The A-series light bulb is the "classic" glass light bulb shape that has been the most commonly used type for general lighting service (GLS) applications since the early 20th century. It has a pear-like shape and is typically fitted to either an Edison screw or a bayonet cap base.

The G45 is a LED Globe shape light bulb. The G refers to the Globe shape and 45 is a reference to the light bulbs width of 45mm. These are also known as Golf Ball LED light bulbs.

The light bulb codes are represented by a letter or a series of letters with a number. Take A21 for example, letter 'A' indicates standard household incandescent shape, and '21' indicates a diameter of 21 divided by 8 inches, or approximately 2.6 inches. There are a variety of light bulb bases sizes also.

For example, if you are wondering “are B10 and B11 bulbs interchangeable,” the answer is usually yes; it just depends on the size of the base.

Additionally, if you elect to use a bulb that has a higher watt label than is advised for your electrical fixture, it could result in direct damage to your fixture. Not only will this result in your having to engage in either the repair or the complete replacement of that fixture, but it could also pose a fire risk.

What is A21 bulb shape? ›

An "A" bulb has the classic light bulb shape, commonly compared to an upside-down pear. The two digits after the letter refer to the bulb's diameter at its widest point, and is measured in eighths of an inch. An A21 bulb, therefore, has a diameter of 21 divided by 8 inches, or approximately 2.6 inches.

All A19 lamps have an E26 base, but not the other way around

The standards that govern the dimensions and design of A19 light bulbs also dictate that it must use an E26 screw base. In other words, all A19 light bulbs also have an E26 base.

​​The A19 and A21 bulbs have the same shape, but the diameter of the first bulb is 2.375 inches. The larger model is 2.625 inches in diameter. You'll also notice the base height difference in the A19​ vs A21 comparison. The A19 is 4.13 inches tall, while the A21 is closer to 5 inches.

Bulb sizing is very straightforward and simple, it is based on the diameter of the bulb at its widest point, measured in eighths of an inch (⅛”). For example, the designation “T12” indicates a tubular bulb that is 12 eighths of an inch (12/8”) in diameter (or 1 ½”).

The letter indicates the shape of the bulb and the number relates to the diameter of the bulb in eighths of an inch. The most commonly used household bulb is the A-19. The bulb is "A" type and the diameter would be 2 3/8" A 120BR40 is a 120-watt reflector 5" in diameter.

Numbers in each code refer to the bulb's diameter in one-eighths of an inch. BR20/R20 bulb: 20/8 = 2-1/2″ diameter. BR30 bulb: 30/8 = 3-3/4″ diameter. BR40 bulb: 40/8 = 5″ diameter. Euri Lighting BR40 LED Bulb - 17W - Dimmable - 100W Incandescent Equivalent - 2700K / 3000K / 4000K / 5000K.

The light bulb has long been used as a symbol of innovation, denoting the origination of a smart idea, the sudden flash of understanding or insight into how to achieve something - often in a new, different and pioneering way.

synonyms: bulb-shaped, bulblike circular, round. having a circular shape. adjective. curving outward. synonyms: bellied, bellying, bulging, bulgy, protuberant protrusive.

The bulb symbol is a circle with a cross through it. Image caption, The LED symbol is a triangle pointing to a straight line. Two arrows show light being emitted.

Round is the strongest structural shape. The incandescent bulb has a thin glass envelope with a vacuum inside, the glass needs to be strong to not break easily; thus a round shape provides the strongest envelope.