Christmas Light Sizes Chart (2025)

It may not be the largest chart in the world, yet charts showing Christmas light bulb sizes can make the difference for that special time of year. There is a wide range of types of Christmas light bulbs available, from incandescent Christmas lights to newer LED Christmas lights. Each has use and offers a very different appearance.

Homes that have too many large bulbs can be brightly lit where most people think it is too much, or lights that are too small lack any wow factor.

In our guide, you can learn more about Christmas light sizes. By the end, you’ll know enough, whether you want to cover your home in bright bulbs so a Santa’s Grotto look, or you just want to hang LED lights around your bushes and trees.

It could also be, you have a Christmas light source already, and you merely want to change a bulb or two. (Read Light Bulb Socket Sizes Chart)

What are Christmas light sizes?

The letter “C” stands for Cone, which is the almost pointy shape most commonly associated with Christmas lights.

C7, C9, and C6 are the most common bulbs, with C5 and C3 being less common.

The number after the C stands for the diameter multiplied by eight:

• C7 bulb: 7/8 = 7/8″ diameter
• C9 bulb: 9/8 = 1-1/8″ diameter

G Shape – Globe (Round)

The bulb shape is round like a globe, and the G30, G40, and G50 bulbs are the most common. The diameter in millimeters is represented by the number. Because 50 mm is difficult to picture, bear the following in mind:

• G30: Slightly smaller than ping pong balls
• G40: Similar size to table tennis balls
• G50: Slightly larger than ping pong balls

Base Sizes

In the United States, there are three typical threaded bulb base sizes for holiday lighting.
The numbers indicate the base’s breadth in millimeters.

• Candelabra: E12 is the size of a standard nightlight
• Intermediate: E17 is often found with C9 bulbs.
• Medium or standard: E26 is found in patio string lights, which were commercial use, yet now have filtered to domestic users since the need for outdoor string lighting has grown.

C7 and C9 cords and bulbs are commonly referred to as “C7 cords and bulbs” and “C9 cords and bulbs,” or “C7 Christmas lights” and “C9 Christmas lights,” respectively.

When selecting an incandescent or LED bulb, make sure it is compatible with the right cord.

Which Is Bigger C7 Or C9 Christmas Lights?

Christmas bulbs come in two standard sizes, C7 and C9. Besides the standard sizes, you can find the round bulbs (above), mini string lights, and patio lights in various shapes, types and sizes.

Mini Christmas lights

The most often used lights are little lights. The bulb has a pointed tip and resembles a candle. They usually have a diameter of 1/4 inch and a height of 5/8 inch.

C6 Holiday Lights

C6 lights are the tiniest of the strawberry-shaped lights that are commonly referred to as “classic Christmas bulbs.” The bulbs are around 3/4 inch in diameter and 1 1/8 inch tall on average.

C7 Christmas lights

The strawberry form of C7 lights is similar to that of C6, but it is significantly larger. They’re 1 1/2 inches in diameter and 1 inch tall. They have a rounded, bulbous appearance due to their breadth.

Christmas Lights C9

Lights C9 are slightly larger than C7 and have the same characteristic strawberry form. C9 lights have a diameter of 1 1/4 inch and a height of 2 1/2 inch.

G12 holiday lights

G Series globes come in a variety of sizes and are shaped like globes. This is the bulb’s maximum diameter in eighths of an inch.

Simply take the number after the G, split it by 8, then round to the nearest inch to get the approximate diameter. G25, for example, is a globe-shaped bulb with a diameter of roughly 3 inches, while G15 is a globe-shaped bulb with a diameter of almost 2 inches. (Learn How Long Do Cut Christmas Trees Last)

Traditional Incandescent Lights vs. LED String

Modern LED bulbs produce a dazzling and energy-efficient light. SMD (Surface Mounted Device) LED bulbs have a small, square chip at the base that is more durable and energy efficient.

Incandescent bulbs are more fragile and may need to be replaced more frequently.

The Projector Series bulbs have a refractive lens that allows brighter LED light to reflect off smooth edges, giving them the appearance of traditional incandescent bulbs. Ceramic, Transparent, and Faceted bulbs give a typical sparkle with a crystal effect.

What Size of Christmas Lights Are Best for House?

Important Tips

Do not overload extension cords.

A 9 ft. extension cord with three plug receptacles can carry 3 light sets of equal length. You can mix and match sets of lights on an extension cord, but not in the same receptacle.

Plug in light strings before decorating.

Plugging lights in the power allows you to check for missing or burned out bulbs and evenly distribute lights throughout the tree.

Plug wire into a surge protector.

Plug your lights into a surge protector to prevent overloading and safeguard them from power spikes.

Use correct voltage and type for replacement bulbs.

Bulb replacements vary as the voltage and bulb type won’t be the same across manufacturers. As an example, a 35 set light bulb cannot be replaced by a 50 set light bulb as the 35 set uses a 3.5 volt bulb and the latter a 2.5 volt bulb.

Decorating Christmas Tree

The simple Christmas tree is the most renowned icon of the holiday season and brings reams of Christmas cheer. Here are some recommendations to make sure you have the appropriate lights and the wire doesn’t melt and burn your tree.

Keep Replacements Handy

You want replacement lights that match the ones you bought for your tree. Buy a set or two extra in case a string breaks over the holidays. If you need to borrow bulbs from another set, make sure you have plenty of bulbs. Borrowing bulbs from another set might cause burnouts and be harmful, especially if the voltages are different. (Learn How To Hang Christmas Lights Around Windows)

Test Lights Before Decorating

We’ve all done it: decorated the tree only to discover an entire string is dead! To avoid this, test each set of lights. Avoid the effort and embarrassment of having to redecorate your tree mid-Christmas dinner by testing for burned out bulbs and partially dead strings.

Light Tree In Sections

Don’t saturate your tree. To make sure your tree is evenly lit, install lights section by section and make adjustments as you go. Instead of wrapping your tree, try a “S” or “wave” pattern.

Decorating Tips for Yard Christmas Lights

Outside home decorating may appear difficult, but with the correct decorations and techniques, it can be as simple as decorating your Christmas tree.

First, make sure your lights are outside approved. Check the UL Listing tag at the end of the light string.

Outdoor usage is permitted for those designated “Indoor/Outdoor”; nevertheless, indoor use alone should never be used outside.

Starting with any bushes and shrubs is recommended, and to do this you can use C7 and C9 strings, and you can then use mini lights over these.

Decorate bushes using an “S” pattern for best results. If you have trees, you can make outdoor trees take on the appearance of an outdoor Christmas tree. Use the tree’s trunk and mini lights. For leaves and branches, use mini lights and C7 randomly place light strings.

If you have a front door, you can hang a string around this to offer a warm welcome.

Hanging Roof Lights

The lights will likely get wet and exposed to the elements, therefore always use lights that are UL Approved for Indoor/Outdoor Use .

To minimize the load on a circuit that has been tripped by your lights, move them to another outlet.

Except for Icicle Lights, small lights are rarely used on rooftops because of low amounts of lighting.

The most frequent light strings are C7 and C9 for a dazzling display. Most C7 and C9 strings are 25 ft long, thus a 100 ft roof will need 4 strings to give off more light.

If your Christmas light bulbs don’t work, don’t hang them. Before connecting your strings, check for broken or missing bulbs and replace them. Replace the entire string if your wires are worn. (Learn How To Grow Christmas Trees)

You will need to ensure plugs and any light socket can fend off rain and snow

How Big is a C3 Christmas Light?

Christmas bulbs come in C3, C6, C7, and C9. This is the shape most commonly associated with Christmas lights. The most common bulbs are C7, C9, and C6, with C5 and C3 bulbs being used less frequently. The C is the diameter divided by 8.

• C3 Bulb: They are the smallest C-series bulbs, measuring 1/2 inch in diameter and 4.5 bulbs tall.
• C6 Bulb: Lights of the C6 shape are the smallest strawberry-shaped lights, sometimes called the “classic Christmas bulb”. The bulbs measure 3/4 inch in diameter and 1 1/8 inch tall.
• C7 Bulb: C7 bulb size is larger than C6 lights and have the same strawberry shape. One inch in diameter and 1 1/2 inches tall. Their breadth gives them a bulbous shape.
• C9 Bulbs: C9 lights are larger than C7 and have the same strawberry shapes as C6 and
• C7. C9 lights are 1 1/4 inch in diameter and 2 1/2 inch tall.
  The wattage of C9 light is up to twice that of C7 light. Because of their power, they are commonly used in commercial applications to illuminate roofs and large areas of your landscape.
• G12 Bulb: The G Series are globe-shaped lights in various sizes. G indicates the bulb’s maximum diameter in eighths of an inch. Take the number after the G, divide it by 8, and round to the nearest inch. Examples of G25 globe-shaped bulbs are G25 with a diameter of about 3 inches and G15 with a diameter of around 2 inches.
• Globe (G) bulbs are available in a variety of bulbs, from golf-ball sized for enclosed installations to crystal ball sizes for display. Larger G light bulbs frequently have carbon or LED filaments, which add to their appeal.

Christmas Light Bulb Size Chart