How Many C9 Bulbs Do I Need per Foot?

Start with socket spacing

C9 is a bulb size, not a fixed bulb-per-foot count. Your socket spacing determines the planning quantity. Twelve-inch spacing is one socket per foot; 15-inch spacing is 0.8 sockets per foot. Multiply lit footage by 12 and divide by spacing in inches. This is a planning estimate: count the sockets in the finished run because the first and last socket positions can change the exact count.

Round each color to packs

For 100 feet, estimate 100 bulbs at 12-inch spacing or 80 at 15-inch spacing. Both need four 25-count packs for a single color, leaving different amounts of spare stock. For an alternating pattern, split the estimated bulb count between colors before rounding. A 100-bulb red-and-green run needs 50 of each color: two red packs and two green packs.

Separate lit and unlit footage

Measure only sections that will hold bulbs when estimating socket line. Record dark transitions and power connections as separate lamp-wire requirements. Measure corners and changes in elevation along the actual installation route, rather than using a house’s frontage as the whole estimate.

Check the job before ordering

Add up each color across the job, then round to full packs. List mounting pieces by surface and keep spare quantities explicit rather than hiding them inside the formula. The calculator estimates material quantities; it does not establish electrical load limits. Confirm wattage, voltage, socket compatibility, and manufacturer limits for your actual products.

Build a job-specific supply list

Use the free material calculator, compare mounting hardware, and review C9 bulbs, socket line and lamp wire, SPT-1 plugs, and clips and stakes.

For model-specific specifications or a bulk quote, call 817-538-8735.