Spacing printed on seed packets is easy to read but hard to apply to a real bed. Plants sit half a spacing in from the edges, rows may be offset, and the count changes with the pattern you choose.
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Enter your bed size, spacing and pattern. The calculator counts the plants that fit, the rows and the area each plant gets, and draws the plan to scale.
grid: plants = floor(length ÷ spacing) × floor(width ÷ row spacing) triangular: rows = floor((width − spacing) ÷ (0.866 × spacing)) + 1, alternate rows shifted half a spacing plants to buy = ceil(plants × (1 + spare %))
Each plant sits half a spacing in from the edge so it has its full share of room. Triangular spacing fits more plants in large beds; in narrow beds it can fit fewer because of the edges.
A 2.4 × 1.2 m bed at 30 cm spacing fits 8 × 4 = 32 plants in a square grid (35 with 10% spares). In triangular rows it fits 30, because a 1.2 m bed only has room for four offset rows.
In a square grid, 4 × 8 = 32 plants. Triangular spacing fits about the same in a bed this narrow.
In large areas it fits about 15% more plants with the same distance between neighbours. In narrow beds, edges can cancel that out.
The distance between plant centres in the row. Some packets also give a wider row spacing for traditional rows.
Yes, in rich soil you can usually reduce spacing slightly, but plants will be smaller and more prone to disease.