C9 bulbs are the larger cone-shaped Christmas bulb on an E17 intermediate screw base that are 3 inches tall (from base-to-tip), best for displays that stand out from a greater distance on rooflines and large outdoor displays. Buy them as replacement or retrofit bulbs in LED for long life and energy efficiency, or incandescent for a classic glow at lower initial cost.
Why Choose C9 Bulbs?
Size is the reason to choose C9. The C9 is the larger cone-shaped bulb at 3 inches tall from base-to-tip — 50% taller than the 2-inch C7 so it stands out from a greater distance. C9 bulbs use an E17 intermediate screw base, so they drop straight into matching C9 socket wire.
That scale is why C9s are a first choice for larger rooflines, buildings, driveways, and large evergreen trees. Line the peak of your roof for even more impact, edge a long driveway, or add height to a commercial display. If you want lights that make a statement, C9 is the size to reach for.
LED vs. Incandescent C9 Bulbs
C9 bulbs are available in either LED or incandescent, and the choice comes down to what you want from the display.
LED bulbs are rated from 20,000 to 60,000 hours with no filament to burn out, which means the same bulbs light your display season after season. An LED bulb draws under a watt, 90% less than the 7-watt C9 incandescent it replaces so you can safely run longer lines of light. They stay cool to the touch making it safe for pets, kids, wreaths, garland and Christmas trees. LED C9 bulbs are dimmable for full control of the look and work great in steady or animated displays (sold separately).
Our LED C9s span three lines. OptiCore® is the professional-grade bulb the pros use because it is built for commercial displays and anyone who wants a professional result at home. On FlexFilament®, a curved LED filament glows through the lens like an antique Edison bulb, giving your display old-world character with modern LED efficiency. On Kringle Traditions®, shatter-resistant polystyrene means the bulb survives on the roofline and the storage bin with color that never fades, chips or cracks. Full specifications for all three live on the LED C9 bulbs page.
Incandescent bulbs produce the classic glow of a traditional Christmas, giving you the look that has lit displays for generations. Incandescent bulbs carry the lowest initial cost per bulb, so you can light a full display for less at the start. C9 bulbs come in 7 watt (plus a 10 watt option available in clear), so you can pick brighter bulbs or more of them on a single line of light. Commercial Grade bulbs rated for an average life of 3,000 hours light six seasons of nightly use, so you replace fewer bulbs over the life of a display.
On both, nickel-plated bases resist corrosion and connect cleanly, saving you time and hassle every season.
As a rule of thumb, choose LED for larger and long-term displays, and incandescent when lowest initial cost is priority one.
Choosing Color, Finish, and Light Display
LED C9 bulbs come in a wide range of colors. On OptiCore®, ten colors including a 3000K warm white give you the full palette for traditional and modern displays alike. On Kringle Traditions®, ten colors cover the classic Christmas palette plus the shades most sets leave out, allowing you to match any display. On FlexFilament®, eight colors give you range across warm vintage tones and true Christmas color. Available in red, green, blue, white, clear and other colors, incandescent bulbs give you the traditional Christmas palette to build a display around.
Finish is how the bulb's lens interacts with the light. OptiCore® bulbs come in diamond-faceted and traditional smooth opaque finishes, allowing you to match the bulb to the look you are building. On Kringle Traditions®, diamond-faceted bulb designs reflect a spectacular light and color halo that carries from a distance. On FlexFilament®, a transparent lens leaves the curved filament in full view, which makes these bulbs a natural fit for patios, porches and anywhere guests stand close. On incandescent, transparent bulbs show the filament, while opaque finishes diffuse the light into a soft, even glow.
Light display is another choice point. On LED, steady and twinkle versions come in the same finishes, so you can add movement without changing the look of the bulb. On incandescent, twinkle bulbs pulse on and off at random, adding movement to a display that would otherwise sit steady.
Buying Replacement & Retrofit Bulbs
The bulbs on this page are sold separately from stringers or other accessories, so you can replace burned-out or broken C9s without buying a whole new light set. C9 bulbs use an E17 intermediate screw base, so they drop straight into matching C9 socket wire and any C9 replacement bulb fits any C9 socket. Bulbs come in multipacks, so you can keep spares on hand.
That common base also makes retrofitting easy. If you have an older incandescent C9 string, swap in LED C9 bulbs and keep your existing stringers. When you do, replace all the bulbs in the string rather than mixing LED and incandescent: the two differ in brightness and color, so a mixed string won't look consistent. Because an LED bulb draws under a watt, 90% less than the 7-watt C9 incandescent it replaces, you can safely run longer lines of light.
Starting from scratch or building a custom display? Buy bulbs and bare sockets separately for full control of length, spacing, wire color, and color mix. Shop C9 stringers and spools for the sockets, then add the bulbs you want from this page.
Pro Tip:
Pro Tip: Want the subtlety of twinkle bulbs sprinkled through your string lights without the whole string twinkling? Mix a handful of twinkle bulbs, which pulse on and off at random, into an otherwise-steady string for subtle, random sparkle. Buy a pack of twinkle bulbs alongside your steady bulbs and space the twinkle bulbs out evenly. Start with every fifth bulb, then add or remove until the amount of movement looks just right for your style.
Frequently Asked Questions:
What does C9 mean on Christmas lights? The "C" stands for the cone shape, and there are two standard Christmas bulb sizes, C7 and C9. The C9 is the larger cone-shaped bulb at 3 inches tall from base-to-tip — 50% taller than the 2-inch C7 so it stands out from a greater distance. C9 bulbs use an E17 intermediate screw base, so they drop straight into matching C9 socket wire.
Are C9 Christmas lights safe? LED C9 bulbs draw less than a watt and stay cool to the touch making it safe for pets, kids, wreaths, garland and Christmas trees. Incandescent C9 bulbs are safe when used as directed but come in 7 watt, plus a 10 watt option available in clear, and get hot, so avoid touching a lit bulb and keep it away from flammable material. Bulbs are rated for indoor and outdoor use, so one string works anywhere you install it. Don't overload a circuit.
Will your C bulbs fit my stringer? Yes, as long as you match bulb size to your stringer socket size. C7 bulbs use an E12 candelabra screw base, so they drop straight into matching C7 socket wire; C9 bulbs use an E17 intermediate screw base, so they drop straight into matching C9 socket wire. They are not interchangeable — a C9 bulb won't screw into a C7 socket, or vice versa. Before you order replacement bulbs, check the base on your existing stringer (or an old bulb) so the new bulbs fit.
Are all incandescent C9 bulbs the same? No. Commercial Grade bulbs rated for an average life of 3,000 hours light six seasons of nightly use, so you replace fewer bulbs over the life of a display. Nickel-plated bases resist corrosion and connect cleanly, saving you time and hassle every season. Triple-dipped color goes on the transparent bulbs in three passes, resisting fading and cracking for rich color that lasts. Opaque bulbs have a classic soft color diffusing the light.
How do you shorten C9 LED Christmas lights? You don't shorten an individual C9 bulb — "shortening" refers to the stringer it screws into. For a shorter length, choose a shorter pre-sized stringer if possible, then add C9 replacement bulbs from this page. If you do have to cut the stringer, cap each end with a zip plug matched to the wire insulation (SPT1 plug for SPT1 wire, SPT2 plug for SPT2 wire), or an outdoor-rated end cap or sealant.
