What is the difference between C7 and C9 Christmas Bulbs?
Choosing Your Christmas Lights: What is the Difference Between C7 and C9?
Shopping for the best Christmas lights?
As you search the web for just the right lights to outline your roofline, walkway, or fence or light your Christmas or outdoor trees, you are bound to see bulbs that are designated as **C7 or C9**.
The Question: What is the difference between a C7 and C9 Christmas light bulb?
Short Answer (The Essentials):
- **C7 bulbs** are about **1.5 inches tall** and have **E12 bases** (nightlight size).
- **C9 bulbs** are roughly **2.25 inches tall** and have **E17 bases**.
Both fit into cords commonly wired in parallel and are favorites of both professional and residential installers. You can choose your favorite bulb and partner it with a cord that has the best wire color and spacing for your project. Continue reading for more photos and links.
Bulb Anatomy: Shape, Size, and Base
Both bulbs are **"cone-shaped"**, hence the **"C"** as the first letter in their designation.
C7 Bulbs (E12 Base)
C7 bulbs have **E12 bases**, which is the same size as a common nightlight base. This is a handy tip: If a bulb fits in a nightlight, then you know it's a C7 bulb with an E12 base.
C7 bulbs - Three popular versions
- Smooth warm white C7 bulb (Left)
- Incandescent (glass with filament) C7 bulb (Center)
- Faceted warm white C7 bulb (Right)
C9 Bulbs (E17 Base)
C9 lights are the larger of the two most traditional Christmas light bulb sizes. They have **E17 threaded bases** that fit into E17 sockets. This is the standard size traditionally used for C9 bulbs, meaning you can often use C9 bulbs as replacements if your cords are in great shape.
C9 bulbs - Three popular versions
- Smooth warm white C9 bulb (Left)
- Incandescent (glass with filament) C9 bulb (Center)
- Faceted warm white C9 bulb (Right)
Looking for the Icy White Look?
Check out the **C7 pure white bulb** for that vibrant, cool LED light.
📺 Video Discussion: Avoiding Returns and Disappointments
Watch this video for more discussion about this topic:
Video Summary & Key Takeaways:
- **Nostalgia:** Traditional C7 and C9 bulbs evoke the classic nostalgic sound of Christmas.
- C7 Tip: The C7 bulb has an E12 base and will fit in an everyday common nightlight. Use this simple test to determine if you have C7 bulbs.
- **C9 Wattage:** C9 bulbs are 7 watts and quite bright, with a clear 10-watt version also available.
- The primary difference between C7 and C9 is **size and wattage**.
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