Determine optimal spacing for lights, bulbs, or decorative elements along a given length for perfect visual balance.
Last updated: March 2026
Distance from start to first bulb
Distance from last bulb to end
Disclaimer: This calculator positions bulbs with equal spacing between centers, with the first and last bulbs placed at the start and end offsets. It does not create equal edge-to-edge gaps; the offset values determine where the first and last bulbs sit. Verify measurements on-site to account for installation constraints, obstructions, and visual adjustments for the specific environment.
Bulb spacing calculates the distance between light fixtures or decorative elements to achieve uniform distribution along a line. This is essential for string lights, recessed lighting, landscape path lights, and any linear lighting installation where visual balance matters.
The calculator accounts for start and end offsets—the distance from walls or boundaries to the first and last bulb. Effective length is the total length minus these offsets, and this remaining distance is divided evenly between bulbs. For outdoor string lights, typical spacing is 12-18 inches; for architectural lighting, spacing depends on fixture beam angle and ceiling height.
The formula divides by (N-1) because with N bulbs, there are N-1 spaces between them. For example, 3 bulbs create 2 spaces. If you only have 1 bulb, the spacing calculation doesn't apply.
Start and end offsets prevent bulbs from being placed too close to walls or posts. Common offsets are 6-12 inches (15-30cm) for decorative lighting, or they may match the spacing between bulbs for a consistent pattern that continues visually beyond the installation.
Install 10 bulbs across a 30-foot patio with 1-foot offsets on each end:
First bulb at 12" from start, then every 37.3", ending 12" before the end.
With only one bulb, spacing between bulbs doesn't apply. The calculator will show the effective length, and you'd typically center that single bulb within the space.
Offsets reduce the total length available for bulb spacing. Larger offsets mean the bulbs will be closer together for the same number of lights, or you'll fit fewer bulbs at your desired spacing.
Yes, this calculator is perfect for planning outdoor string light installations, patio lighting, event decorations, or any evenly-spaced linear lighting project.
Adjust the number of bulbs to achieve your desired spacing. For string lights, 12-18 inches is common. For pathway lights, 6-8 feet. For recessed lights, spacing depends on ceiling height and beam angle.
Not necessarily. Use different offsets if one end terminates at a post (6-12 inches) while the other meets a wall flush (0 inches). Equal offsets create visual symmetry.
Measure from the start, mark the first offset, then mark every calculated spacing distance. Use a tape measure and chalk line for accuracy. String stretched tight works as a guide.
Yes, though recessed lighting also requires considering beam angle and ceiling height. A common rule: space fixtures at ceiling height distance (8-foot ceiling = 8-foot spacing).
This calculator works for straight-line installations. For curves, divide the arc into straight segments, calculate spacing for each, then adjust at transition points for visual continuity.
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