The difference between E26 and A19 is distinct: E26 refers to the 26mm metal screw base, while A19 describes the pear-shaped glass envelope. They are not interchangeable terms but separate components – the base connects to power, while the shape dictates light distribution.
Confusion arises because standard North American bulbs typically combine both, leading consumers to view them as synonyms rather than separate variables.
This guide breaks down the technical specifications of both standards, explaining the effects that make buying decisions confusing. We also cover specific recommendations for using A19 LEDs in pendant lights and enclosed fixtures.
What Are E26 and A19?
To understand the difference, we must look at the governing documents:
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E26 is governed by ANSI C81.61, which sets the standard for electrical lamp bases and holders.
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A19 is governed by ANSI C78.20, which sets the standard for the dimensional characteristics of incandescent lamps (and their LED retrofits).
While they are often coupled, they serve distinct roles in the "luminaire system":
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E26 (The Base): The electromechanical bridge transferring 120V AC from the mains to the driver/filament.
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A19 (The Envelope): The physical diffuser that dictates the Light Center Length (LCL) and omnidirectional distribution.
Bulb Elements: E26 & A19 OverviewWhat Does "E26" Actually Mean?
"E26" refers to the Edison screw, also known as the Medium Edison Screw. Here's the breakdown:
The "26" refers to the diameter of the thread – specifically, 26 millimeters. But for a precise fit, we get into more exact measurements:
The design of the E26 base is simple but effective:
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Shell (Thread): This part connects to the neutral wire.
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Eyelet (Bottom Tip): This connects to the live wire (the hot wire).
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Insulator: A glass or ceramic ring sits between the wires, preventing short circuits.
E26 is the bulb base with a 26mm diameter
What Does "A19" Actually Mean?
"A19" refers to a bulb shape that has a diameter of 19 eighths of an inch. Here's the breakdown:
1. Size Breakdown
When you divide 19 by 8, you get 2.375 inches, or about 60.3 mm. This is the Maximum Overall Diameter (MOD), measured at the widest part of the bulb.
But size isn't just about diameter. The Maximum Overall Length (MOL) for an A19 bulb is typically 4.13 inches (or 105 mm).
Size Breakdown for A19 Bulb2. The Key Factor: Light Center Length (LCL)
For lighting designers, the A19 is more than just a bulb that fits in a socket. It's about where the light comes from.
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LCL Definition: The Light Center Length (LCL) is the distance from the bottom of the bulb's base to the center of the filament (or LED array) that emits the light.
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Standard A19 LCL: Around 3.125 inches.
Why is LCL important? If you swap an A19 bulb for a shorter one (like an A15) in a lamp with a shade, the light source will drop lower. This shift could mess with the cutoff angle, creating unwanted glare or shadowing, especially around the lamp harp.
The A19 design is intentional to make sure the light is positioned exactly where the fixture designer planned it.
The A19 is a bulb with a pear-like shape
Why Is There Confusion Between A19 and E26?
The confusion stems from a classic "Correlation vs. Causation" error in the consumer's mind, driven by how the industry presents these products.
Here are the 4 main reasons why people mistakenly think they have to choose between an A19 and an E26:
1. The "Default Pair" Effect (Ubiquity)
For the vast majority of standard household use (especially in North America and Japan), the A19 shape and the E26 base are virtually inseparable.
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Because they appear together 95% of the time, consumers unknowingly group them as synonyms for "a standard light bulb".
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They rarely encounter an A19 bulb without an E26 base, so they don't realize these are two separate variables. They view them as a single entity.
The default pairing effect of almost all households2. Confusing Packaging Design
On retail boxes, manufacturers often list A19 and E26 side by side, in the same font size and color, without clear labels (such as "Shape: A19" or "Base: E26").
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Visually, this looks like a model comparison.
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It creates a subconscious reaction similar to seeing "iPhone 14" vs. "iPhone 15". The consumer thinks, "Wait, do I need the A19 model or the E26 model?" not realizing one describes the glass and the other describes the screw.
Packaging often lists A19 and E26 unclearly3. The "Read What You See" Habit
When a bulb burns out, people unscrew it and inspect the markings to know what to buy:
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Some manufacturers stamp "A19" prominently on the glass.
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Others stamp "E26" clearly on the metal collar.
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The consumer assumes whatever text they see most clearly is the product name. If they go to the store looking for an "E26" (because that's what their old bulb said) and see a box labeled "A19," they panic, thinking it's the wrong type.
Consumers tend to assume that the most prominent text is the product name4. Poorly Designed Online Filters
On many e-commerce sites (like Amazon), the search filters can be messy:
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Sometimes, "Bulb Type" is a single dropdown menu that combines shapes and bases.
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When a user sees a list containing LED, Smart, A19, E26, Soft White, it reinforces the idea that these are mutually exclusive categories rather than different attributes of the same product.
The product filters on e-commerce site are confusingWhat Are The Key Differences Between E26 vs. A19?
A19 refers to the shape and size of the bulb, while E26 specifies the type of screw-in base. An A19 bulb has a classic pear shape, about 2.4 inches in diameter. The E26 base is a 26mm Edison screw connector designed for standard medium-sized sockets commonly used in North America.
Most household bulbs combine both: an A19 shape on an E26 base. The confusion arises because these terms often appear together, but they're not interchangeable.
It’s like describing a car: "sedan" refers to the body style, and "five-bolt pattern" refers to the wheel mounting system – both describe the same vehicle, but they reference different components
To visualize the differences, here is a direct comparison:
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Feature
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E26
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A19
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Category
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Base (Cap)
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Shape (Envelope)
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Refers To
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The metal screw threads at the bottom.
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The glass/plastic dome at the top.
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Measurement Unit
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Millimeters (26mm)
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Eighths of an inch (19/8")
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Primary Function
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Electrical connection and mechanical support.
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Light distribution and aesthetics.
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Can it change?
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No. If the base is wrong, it won't power on.
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Yes. You can have different shapes (A15, A21) on an E26 base.
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Geography
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Standard in North America & Japan.
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Standard "Arbitrary" shape globally (though metric sizes vary).
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The Crucial Distinction:
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You can have an E26 base on a bulb that is NOT A19 (e.g., a BR30 floodlight, a decorative globe G25, or a vintage Edison tube).
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You generally cannot have an A19 bulb without an E26 base (in the US market), as the A19 shape is too large for the smaller candelabra (E12) bases.
Key differences between E26 base and the A19 bulbTips for Choosing the Right Bulb (Advanced Selection Guide)
When selecting bulbs for complex projects, simply choosing one that "fits" isn't enough. You need to consider important factors like thermal management and dimming compatibility. Here's a breakdown of 3 key considerations:
1. Enclosed Fixture Rating (Avoid Overheating)
LED bulbs, like the A19, contain components (such as capacitors and rectifiers) that generate heat.
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The Problem: In traditional incandescent A19 bulbs, heat can easily escape. But for LED A19s, heat must be transferred away through the base.
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Tip: If you're using an A19 LED in a fully enclosed fixture, like a glass globe ("boob light"), make sure it's specifically rated for enclosed fixtures. Regular A19 LEDs will overheat in such spaces, which could cause the bulb to fail prematurely as the internal components break down.
2. Beam Angle and Light Distribution
Not all A19 bulbs are the same when it comes to light coverage.
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Standard A19 LED: Typically has a plastic covering that only distributes light upward and outward (about a 220° beam angle).
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Filament A19 LED: Designed to mimic the look of a traditional filament bulb, providing true omnidirectional light (360°), ideal for table lamps where you need to light the area around the base as well.
3. A19 vs. A21 (For High Lumen Needs)
If you need more than 1600 lumens (roughly the output of a 100W incandescent), an A19 bulb might not cut it.
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Why Upgrade: A19 bulbs typically don't have enough surface area to dissipate heat effectively at higher brightness levels.
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What to Look For: Upgrade to an A21 bulb. It's 2.625 inches wide (compared to 2.375 inches for an A19). Before purchasing, measure your fixture's size — an A21 bulb may touch the glass in smaller enclosures, which can cause heat-related damage.
4. Choosing the Right Socket Material
In environments with high humidity or coastal areas:
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Avoid Aluminum E26 bases as they tend to oxidize, which can cause them to fuse with the socket.
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Opt for Nickel-Plated Brass E26 bases instead, as they prevent galvanic corrosion and are more durable in harsh conditions.
Which Bulb Should You Use for a Pendant Light?
For a pendant light, choose an A19 bulb with an E26 base, the standard for most North American fixtures. The A19 shape provides even, omnidirectional light, perfect for open pendant designs.
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Check your pendant's socket type: While most use an E26 base, some decorative fixtures may require an E12 or E17 base. Verify the socket or fixture specs before buying.
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Consider bulb size: A19 bulb, 2.4 inches in diameter and 4 inches in length, fits most pendant shades. For smaller pendants, try A15 bulbs, which are slightly smaller but have the same E26 base.
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Choose the right brightness: For a dining pendant, aim for 800-1,100 lumens (60-75W equivalent). For ambient lighting, 450-800 lumens (40-60W equivalent) is ideal.
3 elements to consider when choosing bulb and base for your pendant lights
Beyond socket type, bulb size, and lumen output, wattage compatibility completes the selection process for light bulbs for pendant lights. Achieving 800-1,100 lumens for dining pendants requires 13-17W LEDs, 43-53W Halogens, or 14-19W CFLs, while 450-800 lumens for ambient lighting needs 8-13W LEDs, 29-43W Halogens, or 9-14W CFLs. Match these to your fixture's maximum rating, generally 60W for enclosed shades or 100W for open designs.
Frequently Asked Questions about E26 and A19 bulbs
Are E26 and A19 bulbs interchangeable?
No, E26 refers to the type of base (26mm threaded connector), while A19 refers to the shape of the bulb (pear-shaped, about 2.4 inches wide).
An "A19 E26 bulb" is a pear-shaped bulb with an E26 base. All A19 bulbs use E26 bases, but E26 bases are also used for other bulb types like BR30, PAR38, and G25.
Is E26 a standard bulb?
E26 refers to the standard base size for most household bulbs in North America. It is not a complete bulb type.
The E26 base fits most fixtures, like lamps and ceiling lights. The term "E26 bulb" can refer to different bulb shapes (such as A19, BR30, or vintage Edison), but the base is always E26. The most common "standard bulb" is the A19 shape with an E26 base.
The E26 base accommodates various bulb shapes beyond A19, but understanding E26 vs E27 base distinctions is crucial for international compatibility. E26 bases operate on 120V North American systems with 3.25mm insulator height, while E27 bases require 220V systems with enhanced 5.0mm insulation for safety. This voltage and safety specification difference makes them electrically incompatible despite similar threading.
Is A19 a standard bulb base?
No, A19 is not a bulb base; it refers to the shape and size of the bulb itself.
Specifically, A19 describes a pear-shaped bulb that is typically 2.375 inches (60mm) in diameter and 3.9 to 4.3 inches (100-110mm) in length.
Can I use an Incandescent A19 bulb in any fixture?
Yes, you can use an A19 incandescent bulb in any fixture compatible with the A19 size and E26 base. But you should verify wattage limits, fixture design, and ventilation to ensure safety and optimal performance.
What happens if I use an A19 bulb with an E27 base?
If you use an A19 bulb with an E27 base in an E26 socket, it may fit physically, but it is not recommended due to the potential electrical compatibility issues.
The E27 bulb is designed for 220-240V systems, while E26 sockets are for 120V, which could cause electrical malfunctions or damage.
Conclusion
This article clarifies the difference between E26 bases and A19 shapes, helping you choose the right bulb for your needs. E26 refers to the threaded base, and A19 to the classic pear-shaped bulb, together forming the standard household bulb in North America.
Understanding these specs ensures proper fit and performance. For handcrafted pendant lights, A19 LED bulbs with E26 bases provide efficient lighting that highlights natural materials like rattan and bamboo.
IndochinaLight's rattan light fixtures, compatible with E26 bulbs, combine traditional craftsmanship with sustainable design, adding warmth and character to your home.
IndochinaLight – IndochinaHomeDecor LLC
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Address: 30 N Gould St Ste. N, Sheridan, WY 82801
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Phone: (+1) 307 249 0594
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Email: service@indochinalight.com
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