Plants Per Square Foot Calculator

Convert the on-center spacing to feet by dividing inches by 12, then take the area each plant occupies. For a square grid that area is the spacing squared, so plants per square foot equals 1 divided by spacing squared. For a triangular layout the area per plant is the spacing squared times 0.866, which raises the density. Multiply that density by your bed area in square feet to get the total plant count.

Square spacing lines plants up in straight rows and columns, so each plant sits in a square cell. Triangular (or staggered) spacing offsets every other row by half a plant, so the rows nest together. At the same on-center distance, a triangular layout fits about 15.47 percent more plants because each plant covers a smaller cell (0.866 times the square cell). Triangular is common for ground covers and mass plantings where you want full coverage.

On-center spacing is the distance from the center of one plant to the center of the next, not the gap between their edges. Plant tags and spacing charts almost always give this number, for example 12 inches on-center or 18 inches on-center. Using center-to-center distance keeps the math consistent no matter how wide each plant grows.

You cannot plant a fraction of a plant, so the whole-plant figure is rounded down from the exact value to stay within your bed at the chosen spacing. The exact (un-rounded) count is shown separately so you can see how close you are to the next plant. Round up yourself if you want full edge coverage or a few spares.

Break the bed into rectangles, add their areas together, and enter the total under the area option. For circles, use 3.1416 times the radius squared to get the square footage first. The plant density only depends on spacing and pattern, so once you have an accurate area in square feet the count is straightforward.

Closer spacing fills in faster and suppresses weeds sooner, but it costs more plants and can crowd them as they mature. Wider spacing is cheaper and gives each plant room, though the bed looks sparse at first and needs more mulch and weeding in the meantime. Follow the mature-width guidance on the plant tag, then pick a pattern based on how quickly you want full coverage.