Measure the widest point of your current globe straight across the middle. That diameter in inches is your globe size. The most common residential sizes are 6, 8, 10, and 12 inches, while commercial and municipal fixtures typically use 14 through 20-inch globes. If your globe is broken or missing, measure the inside diameter of the fitter (the metal ring on top of the post) and match it to a globe with the correct neck size.
Globe fitter sizes follow electrical lamp standards that have been in use for over a century.
Getting the wrong size means a trip back to the store or another online order. This guide covers every measurement you need, the four neck types, standard sizes, and which KASTLITE globe fits your fixture.
How to Measure Your Lamp Post Globe
You need three measurements to order the right replacement globe: diameter, neck opening, and neck type. Grab a tape measure and follow these steps.
Step 1: Measure the Globe Diameter
The diameter is the single most important number. Place the globe on a flat surface with the opening facing sideways. Hold a ruler or tape measure across the widest point (the "belly" of the globe) and read the measurement. Round globes are straightforward. For acorn-shaped or teardrop globes, wrap a flexible tape measure around the widest section to get the circumference, then divide by 3.14 to calculate the diameter.
Globe diameters come in even-number increments: 6", 8", 10", 12", 14", 16", 18", and 20". If your measurement falls between two sizes (for example, 9.5 inches), the globe was likely manufactured as a 10-inch model and has shrunk slightly from heat exposure over the years.
Step 2: Measure the Neck Opening
Turn the globe upside down and look at the bottom opening. Place a ruler across the opening at the widest point and measure the outside diameter of the neck or flange. This number tells you which fitter your globe is designed for.
The outside diameter of the neck is always slightly smaller than the fitter it sits in. For example, a globe with a 3.91" neck fits a standard 4" fitter. Here are common neck-to-fitter pairings:
| Neck Outside Diameter | Fits This Fitter Size | Typical Globe Sizes |
|---|---|---|
| 2.81" | 3" fitter | 6" |
| 3.14" | 3.25" fitter | 6" |
| 3.24" | 3.5" screw lock | 8" |
| 3.50" | 3.5" neckless | 8" |
| 3.91" | 4" fitter | 8", 10" |
| 3.94" | 4" twist lock | 10", 12" |
| 4.625" | 4-5/8" custom | 10", 12" |
| 5.25" | 5.25" neckless | 12", 14", 16", 18", 20" |
| 8.0" | 8" fitter | 16", 18", 20" |
Step 3: Identify the Neck Type
Look at the bottom of your globe (or at the fitter on your post). The neck type determines how the globe attaches to the fixture. There are four common types, and they are not interchangeable. We cover each one in detail in the next section.
Neck Types Explained
The neck is the connection point between the globe and the fixture. Ordering the wrong neck type is the most common mistake buyers make, even if the diameter is correct. Here are the four types you'll encounter.
Fitter Neck
A fitter neck is a short cylindrical extension at the base of the globe. It slides down into a metal fitter ring mounted on top of the post. Three or four small grooves or notches on the neck align with tabs or set screws on the fitter to hold the globe in place. This is the most common connection type for residential post lights in the 8" to 12" range. Standard fitter sizes include 3.14", 3.91", and 4" outside diameter.
KASTLITE carries fitter neck globes across all sizes. For example, our 8" Globe with 3.91" Fitter Neck and 12" Globe with 3.91" Fitter Neck both fit standard 4-inch post top fitters.
Twist Lock Neck
A twist lock neck looks similar to a fitter neck but uses a bayonet-style locking mechanism. You insert the globe into the fitter and rotate it about a quarter turn to lock it into place. This design prevents the globe from vibrating loose in windy conditions. Twist lock necks are common in the 3.94" and 4-5/8" sizes, particularly on 10" and 12" globes.
Check out the 10" Globe with 3.94" Twist Lock Neck or 12" Globe with 3.94" Twist Lock Neck if your fixture uses this connection.
Neckless (Open Bottom)
A neckless globe has no protruding neck at all. The bottom is simply an open hole. The globe sits on a metal band or ring with set screws and a rubber gasket that grips the globe from the outside. Neckless designs are standard on larger commercial globes (14" to 20") and many 8" and 12" residential fixtures. The most common neckless opening sizes are 3.50" and 5.25".
KASTLITE's 14" Globe with 5.25" Neckless Opening and 20" Globe with 5.25" Neckless Opening are popular choices for municipal and HOA lighting projects.
Screw Neck
A screw neck has external threads on the neck that screw directly onto a threaded collar on the fixture. This is less common than fitter or neckless styles and is mostly found on smaller 6" and 8" globes for decorative residential fixtures. The threads provide a secure hold and make bulb changes simple: unscrew the globe, replace the bulb, screw it back on.
Our 6" Globe with 3.14" Screw Neck is an example of this type.
Standard Lamp Post Globe Sizes
KASTLITE manufactures globes in eight standard diameters. Here's a breakdown of each size, where it's typically used, and what fixtures it fits.
| Globe Size | Common Applications | Available Neck Types | KASTLITE Collection |
|---|---|---|---|
| 6" | Residential walkway lights, decorative path lighting, small post tops | Fitter (3.14"), Screw (3.14"), Neckless (2.81") | Shop 6" Globes |
| 8" | Residential post lights, porch fixtures, garden lighting | Fitter (3.91"), Screw Lock (3.24"), Neckless (3.50") | Shop 8" Globes |
| 10" | Most common residential size, mailbox posts, driveway entrances | Fitter (3.91"), Twist Lock (3.94"), Custom (4-5/8") | Shop 10" Globes |
| 12" | Residential and light commercial, community entrances, large post lights | Fitter (3.91"), Twist Lock (3.94", 4-5/8"), Neckless (5.25") | Shop 12" Globes |
| 14" | Commercial properties, parking lots, HOA communities | Neckless (5.25") | Shop 14" Globes |
| 16" | Commercial and municipal, streetscapes, parks | Neckless (5.25"), Fitter (8") | Shop 16" Globes |
| 18" | Municipal street lighting, large parking areas, campus walkways | Neckless (5.25"), Fitter (8") | Shop 18" Globes |
| 20" | Boulevards, plazas, tall commercial poles, major thoroughfares | Neckless (5.25"), Fitter (8") | Shop 20" Globes |
The 10" and 12" sizes account for the majority of residential replacement orders. If you're replacing a globe on a standard mailbox post or driveway lamp, it's almost certainly one of these two sizes. For commercial and municipal projects, 14" through 20" are the standard range.
Globe Shapes: Round, Acorn, and Teardrop
Globe diameter and neck type tell you what fits your fixture. Shape is primarily an aesthetic choice, but it does affect light distribution and compatibility.
Round (Sphere) Globes
Round globes are the classic shape. They distribute light evenly in all directions, which makes them a good choice for general area lighting. Every KASTLITE size from 6 inches through 20 inches is available in a round shape. If you're replacing a broken globe and aren't sure what shape you had, round is the safest bet for most residential fixtures.
Acorn Globes
Acorn globes have a pointed top and a wider body that tapers toward the neck. They're common in municipal and HOA lighting because of their traditional appearance. Acorn globes direct slightly more light downward compared to round globes, which can reduce light trespass into neighboring yards.
The globe shape dates back to the era of gas lighting, when glass enclosures protected open flames from wind and rain.
KASTLITE manufactures acorn globes in both our own line and Lexalite-compatible replacements. Acorns typically use fitter necks in the 8" or 9-1/8" range. Browse the full Globes and Acorns collection for all available options.
For help choosing between acorn styles, read our guide: Best Acorn Lamp Post Globe Replacement for Outdoor Lighting.
Teardrop Globes
Teardrop globes (also called "pendant" or "pear" shaped) have a wider top and a narrower bottom. They hang from fixtures rather than sitting on top of posts, making them popular for pendant-style and pier mount applications. KASTLITE's teardrop collection includes options for both indoor and outdoor use.
Materials: Acrylic vs. Polycarbonate Globes
KASTLITE manufactures globes in two primary plastics: acrylic (PMMA) and polycarbonate (PC). Both outperform glass for outdoor use because they weigh less and don't shatter into dangerous shards. Here's how they compare for lamp post applications.
| Property | Acrylic (PMMA) | Polycarbonate (PC) |
|---|---|---|
| Clarity | 92% light transmission (glass-like) | 88% light transmission |
| UV Resistance | Excellent. Resists yellowing for years in direct sun | Good with UV coating. Without it, yellows faster than acrylic |
| Impact Strength | Moderate. Can crack from a hard impact (thrown rock, hail) | 250x stronger than glass. Resists vandalism and severe weather |
| Scratch Resistance | Better than polycarbonate. Easier to polish out minor scratches | Scratches more easily. Harder to restore |
| Weight | Slightly heavier | Slightly lighter |
| Best For | Residential neighborhoods, HOA communities, low-traffic areas | Parks, commercial lots, roadsides, vandal-prone locations |
A practical rule of thumb: if your globe sits where someone could throw a rock at it or where hailstorms are common, go with polycarbonate. If it's in a protected residential area and you want maximum clarity, choose acrylic. For more detail on outdoor material durability, see our article: What Materials Last Longest for Outdoor Lighting Globes?
What If Your Globe Is Broken or Missing?
If you can't measure the old globe because it shattered or was removed, you still have options:
- Measure the fitter. Place a ruler across the metal fitter ring on top of your post and measure the inside diameter. Match that to the "Fits This Fitter Size" column in the neck table above.
- Measure the post diameter. The post diameter can narrow down the globe size. A 3" diameter post typically holds a 10" or 12" globe. Larger 4" posts may use 14" or 16" globes.
- Check the fixture manufacturer. Look for a label or stamp on the fixture with a model number. Search that model number online to find the original globe specs.
- Contact KASTLITE. Send us a photo of the empty fixture with a ruler placed across the fitter opening. Our team can identify the correct replacement in most cases.
Frequently Asked Questions
Can I use a different size globe than my original?
You can go up or down one size (for example, swapping a 10" globe for a 12") as long as the neck type and fitter dimensions match. A larger globe will cast a wider light pattern and may look proportionally better on a tall post. A smaller globe concentrates the light but may look undersized. The neck dimensions are what actually determine fit, not the globe diameter itself.
What is the most popular lamp post globe size?
The 10-inch globe is the most popular for residential applications. It fits standard mailbox posts, driveway entrance lights, and garden lamp posts. The 12-inch is a close second, especially for newer homes and HOA-standard fixtures.
How do I know if I need a fitter neck or neckless globe?
Look at the top of your lamp post. If there's a metal ring with an open center hole, you need a fitter neck globe that slides into the ring. If there's a flat metal band or plate with set screws around the outside edge, you need a neckless globe that sits on top and gets clamped from the outside.
Does KASTLITE make custom-size globes?
Yes. KASTLITE manufactures custom globes in our Clearwater, Florida facility. We can produce non-standard diameters, neck dimensions, colors, and finishes. Custom orders typically require a minimum quantity. Contact us for a quote on your specific project.
What color options are available?
Standard options include white (opal), clear, and smoke. White globes hide the bulb and create a soft, even glow. They're the most popular choice for residential and commercial installations. Clear globes show the bulb and produce maximum brightness, which works well for security lighting. We also offer colored globes in select sizes for decorative applications.
How do I measure an acorn-shaped globe?
Wrap a flexible tape measure around the widest point of the acorn (the "belly," not the pointed top). Record the circumference. Divide that number by 3.14 to get the diameter. For example, if the circumference is 37.7 inches, the diameter is 12 inches (37.7 / 3.14 = 12.0).
Are KASTLITE globes made in the USA?
Yes. KASTLITE manufactures acrylic and polycarbonate globes at our facility in Clearwater, Florida. All globes are made from US-sourced materials with in-house quality control on every unit.
Shop KASTLITE Lamp Post Globes by Size
Browse our full selection of replacement lamp post globes organized by diameter. Every globe is manufactured in the USA with UV-stabilized materials and backed by our quality guarantee.
Choosing between acrylic and polycarbonate for your globe? Our complete properties reference compares both materials with ASTM test data.
Not sure what wall thickness you need for your globe? Our plastic sheet thickness guide covers lamp post globe thickness recommendations.
For ceiling light covers and panels, see our light cover measurement guide covering flat panels, wraparounds, troffers, and more.
- 6" Lamp Post Globes
- 8" Lamp Post Globes
- 10" Lamp Post Globes
- 12" Lamp Post Globes
- 14" Lamp Post Globes
- 16" Lamp Post Globes
- 18" Lamp Post Globes
- 20" Lamp Post Globes
Not sure which globe fits your fixture? Check our guide on how to choose the right lamp post globe for outdoor lighting, or contact our team with a photo of your fixture and we'll help you find the right match.
Need a complete fixture, not just the globe? Browse our Globe Combos (globe + fitter + bulb in one package) or Pier Mount Lighting for post-free installations.