About the Plant Spacing Calculator
This plant spacing calculator tells you how many plants you need to fill a bed, border or ground-cover area at a given spacing. Enter the length and width of the area in feet, the recommended plant spacing in inches from the seed packet or nursery tag, and choose a square grid or a staggered (triangular) pattern.
Triangular spacing — where every other row is offset by half a space — packs about 15% more plants into the same area while keeping every plant the same distance from its neighbors. It is the standard layout for ground covers, perennials and hedges. Square spacing is easier to lay out and suits vegetable rows and square-foot gardening.
The count is based on the area each plant occupies, which is how nurseries and landscape designers estimate plant quantities. Along edges you may fit a few more or fewer plants depending on where you start; add a few spares for replacements.
With the default inputs, the plants needed is 40 plants. Change any value above to recalculate instantly.
How to use the plant spacing calculator
- 1Measure the length and width of the bed in feet.
- 2Look up the recommended spacing on the plant tag or seed packet.
- 3Choose square grid or triangular (staggered) spacing.
- 4Enter the price per plant to budget the planting.
- 5Buy a few extra plants to replace any that fail.
Formula and method
Each plant in a square grid occupies a square s × s, so the number of plants is the area (in square inches) divided by the spacing squared. In a triangular layout rows are offset and only s × √3⁄2 ≈ 0.866 s apart, so each plant occupies a smaller rhombus of s² × 0.866 and roughly 15.5% more plants fit.
The area is length × width converted to square inches (× 144). Results are rounded down to whole plants. This area-based method is the standard estimating approach; the exact count along edges depends on where the first row starts.
- N
- Number of plants
- A
- Planting area in square inches
- s
- Center-to-center spacing in inches
- 0.866
- √3 ÷ 2, the row factor for triangular spacing
Worked examples
10 × 4 ft bed at 12 inch spacing
The bed is 40 sq ft (5,760 sq in). At 12 inches each plant takes 144 sq in, so a square grid fits 40 plants; a triangular layout uses 144 × 0.866 ≈ 124.7 sq in per plant and fits 46. At $3.50 each, the square layout costs $140.
20 × 3 ft border at 18 inches, staggered
A 60 sq ft border is 8,640 sq in. Each plant at 18 inches needs 324 sq in in a grid (26 plants) or 324 × 0.866 ≈ 280.6 sq in staggered, giving 30 plants.
Ground cover at 6 inches over 100 sq ft
At 6 inch spacing a square grid needs 14,400 ÷ 36 = 400 plants, while a triangular layout needs 14,400 ÷ 31.18 ≈ 461 plants for 100 sq ft of ground cover.
Frequently asked questions
How many plants per square foot at 12 inch spacing?+
One plant per square foot in a square grid, or about 1.15 plants per square foot with triangular spacing. At 6 inches it is 4 per sq ft (square) or about 4.6 (triangular).
What is triangular or staggered spacing?+
Plants in alternate rows are offset by half the spacing so each plant sits at the point of an equilateral triangle. Every plant stays the same distance from its neighbors, but rows are closer together, so more plants fit.
Should I use the spacing on the seed packet?+
Yes — packet and tag spacing reflects the mature spread of the plant. Planting closer gives quicker coverage but more competition and disease risk; wider spacing takes longer to fill in.
How do I calculate plants for an irregular bed?+
Split the bed into rectangles, calculate the area of each, add them together and enter an equivalent length and width (for example area × 1 ft). The per-square-foot figure also lets you multiply any area directly.