When you need this calculation
Buying plants for a new bed, ground cover or hedge, planning a vegetable garden, or checking a landscaper’s quote. Plant labels give spacing in inches or centimeters; the calculator turns that into a count for the whole area.
How the count is worked out
Each plant needs a square of ground as wide as the spacing, so in a grid the count is the bed area divided by spacing squared. With staggered rows the plants pack in a pattern of equilateral triangles: rows are only 0.866 of the spacing apart, so each plant takes 0.866 × spacing² of ground.
The calculator converts everything to the same unit first, so 12 inches becomes 1 foot (an area of 1 sq ft per plant) and 30 cm becomes 0.3 m (0.09 m² per plant).
Grid or staggered?
Grids are easy to lay out and suit vegetables in rows or square foot gardening. Staggered rows cover ground more evenly, which is why they’re used for ground cover, hedges and mass plantings. They need about 15% more plants for the same spacing.
Common mistakes
Measuring spacing between rows, not plants. In a staggered layout the plant spacing is the distance between neighbors in the same row; the rows themselves are closer.
Planting to the very edge. Along a path or wall, the outermost plants usually sit half a space in from the edge, so a long narrow bed can fit slightly fewer plants than the area suggests.
To fill the bed first, use the raised bed soil calculator or the mulch calculator.