Globe and G-Bulb Lights on Christmas Trees Explained

What Are Globe Bulbs?

Globe bulbs, also known as G-bulbs, are spherical Christmas tree lights that give a soft, full glow. Unlike tiny mini-bulbs, globes are larger and more visible, adding a traditional holiday look. They come in a range of diameters, from small globes that fit easily among branches to large statement bulbs that become a main feature.

We see globe bulbs most often on pre-lit trees that aim for a warmer, more vintage feel. Many manufacturers use them in their pre-lit Christmas trees, and they are also available as replacement strands for unlit trees.

The appeal of globes is their simplicity. A round glass envelope wraps the filament or LED evenly, casting light in every direction. That makes them ideal for filling the negative space between branches, especially on fuller tree profiles.

How Globe Bulb Size Codes Work

The name of a globe bulb typically begins with the letter G, followed by a number. That number is a direct indicator of the bulb's diameter. Although the exact unit varies between manufacturers, the convention is consistent: a larger number means a physically larger bulb. For instance, a G-series bulb with a higher number will have a wider glass globe than one with a lower number, even if the socket and voltage are identical.

Many people confuse globe bulb size with the older C7 and C9 candelabra bases. The G-code is about the glass envelope, not the base. If you are replacing bulbs, you need to match both the base type and the overall size, which we cover in our guide to Christmas tree light bulb types.

Common globe sizes you will find in stores include G12, G16, G25, G30, and G40. The higher the number, the larger the diameter. On a typical six-foot tree, G16 bulbs read as a medium option, while G40 bulbs are noticeably larger and often used on outdoor trees or as statement pieces. For indoor artificial trees, most pre-lit strands use smaller globes, around G12 to G16, to keep the branch structure visible.

When you pick a globe size, think about the tree's scale. A tiny tabletop tree can look overwhelmed by large globes, while a towering tree may need big bulbs to be visible from across the room. For inspiration, see our picks for small tabletop trees and tall pre-lit trees.

Choosing the Right Globe Size for Your Tree

There is no single 'correct' globe size, but a simple rule of thumb applies: the bulb should be proportionate to the tree. On a 4-foot tabletop tree, smaller globes keep the light balanced; on an 8-foot full tree, larger globes add presence without getting lost. Our 6 to 6.5 ft tree guide and 9 ft and taller guide give you examples of what to look for in overall light scale.

If you are adding globes to an unlit tree, think about how many strands you will need and how the light will spread. Bigger bulbs often have wider spacing on the string, so you may need more strands to fill the same area. Our how to add lights to an unlit tree can help you plan.

Another consideration is the density of your tree's branches. A full, lush tree can absorb more light, so you might want a larger globe or a higher strand count. A slim, pencil tree benefits from smaller globes that follow the vertical line without bulking it out. For slim styles, see our pencil tree guide.

LED Globe Bulbs: Efficiency and Longevity

LED globe bulbs are a popular upgrade because they run cooler and cost much less to operate. According to the ENERGY STAR program, certified LED decorative light strings use about 92% less energy than conventional incandescent strings. They also last significantly longer, so you will not replace them as often. ENERGY STAR certified decorative light strings are available in many globe shapes and colors, and we recommend looking for that label when shopping.

Because LEDs give off almost no heat, they are safer near dry branches and leave your tree cool to the touch. For more on the differences, see our LED vs. incandescent comparison.

LED globes also open up new design possibilities. Many brands offer color-changing LEDs, allowing you to cycle through white, warm white, red, green, and blue effects with a remote. If that appeals to you, browse our color-changing tree guide for ideas and specifications.

Keep in mind that not all LED globes are dimmable. If you plan to use a dimmer switch, verify that the packaging says 'dimmable' before you buy. Our guide to LED color temperature can help you choose between warm, cool, and daylight white output.

Safety and Certification for Globe Light Strings

Whatever bulb shape you choose, safety starts with the string itself. The U.S. Fire Administration recommends keeping your tree at least 3 feet away from heat sources and inspecting lights each year for frayed wires. Overloaded outlets and faulty wiring are the most common causes of holiday fires, as the National Christmas Tree Association points out.

Look for lights that carry an independent certification mark, such as the ETL Listed Mark from Intertek. That mark means the product has been tested to applicable safety standards by a Nationally Recognized Testing Laboratory. See our safety standards guide for more on what these labels mean.

Before you hang any string, check the wire insulation for cracks or pinch points. If a strand feels warm to the touch after a few hours, that is a sign it may be overloaded or faulty. Read the manufacturer's instruction on how many strands you can safely connect end to end, and never exceed that number.

Also, consider where you place the tree. Keep it away from fireplaces, radiators, and candles. Ensure it does not block exits, and water a real tree daily. If you have a pre-lit artificial tree, check that the power adapter is certified and do not run cords under rugs where they can be damaged.

What to pick for your use

Questions

What does the G mean in globe light codes?

The G stands for globe, and the number that follows indicates the diameter of the bulb. A larger number means a wider bulb.

Can I mix globe bulbs with mini bulbs on the same tree?

Yes, but be aware that the visual effect will be mixed. If you want a uniform look, stick to one style per section or use globe bulbs as accents.

Are LED globe bulbs dimmable?

Some are. Check the packaging or the product information for dimming compatibility, because not all LED strings dim like incandescent ones.

Do globe bulbs get hot?

Incandescent globes can get quite warm, while LED globes stay cool. For safety, keep lights away from flammable materials and consider LED for longer use.

How do I know which globe size fits my tree?

Think about the overall scale. A simple approach: do not use bulbs that are larger than the ornaments you plan to hang, unless you want the lights to be the main event.