Plant Spacing Calculator
Squeezing the Right Number of Plants Into a Bed
Cram vegetables too close together and they compete for light, water, and root room — yields drop and disease pressure climbs from poor airflow. Space them too far apart and a bed that could hold forty plants ends up holding twelve. Seed packets and plant tags give a spacing figure in inches or feet; this calculator turns that single number, plus your bed dimensions, into an exact plant count.
The Formula
The calculator treats the bed as a grid, fitting as many full spacing intervals as possible along each dimension:
Rows = floor(Bed Width ÷ Plant Spacing)
Total Plants = Plants per Row × Rows
The floor() function rounds down to a whole plant — a leftover partial interval at the edge of the bed isn't counted, since a fraction of a plant slot won't fit a full-grown plant.
Worked Examples
| Bed Dimensions | Plant Spacing | Grid | Total Plants |
|---|---|---|---|
| 10 ft × 4 ft | 2 ft | 5 × 2 | 10 |
| 6 ft × 3 ft | 9 in (0.75 ft) | 8 × 4 | 32 |
Typical Spacing by Crop
Spacing recommendations come from seed packets and extension-service planting guides and vary by variety, but these commonly published ranges are a reasonable starting point:
| Crop | Typical Spacing |
|---|---|
| Carrots, radishes | 2–3 in |
| Lettuce, spinach | 8–12 in |
| Bush beans | 4–6 in |
| Bell peppers | 18–24 in |
| Tomatoes (staked) | 24–36 in |
| Squash, pumpkins | 36–48 in |
Ranges are general guidance — always check the specific variety's seed packet, since spacing can shift with plant habit (bush vs. vining) and mature size.
Why Grid Spacing Matters
- Seed and transplant ordering — knowing the exact plant count before planting day avoids running short mid-row or over-ordering starts you'll have to discard.
- Airflow and disease control — correct spacing keeps foliage from staying wet and touching, which is a major factor in fungal diseases like powdery mildew and blight.
- Succession planning — gardeners staggering plantings across a season use the per-bed count to divide seed stock across multiple sowing dates.
How to Use This Calculator
- Enter the bed length in feet.
- Enter the bed width in feet.
- Enter the plant spacing in feet (convert inches to feet first, e.g. 9 in = 0.75 ft).
- Select Calculate to see the total number of plants the bed will hold in a grid layout.
Related Calculations
Once you know how many plants you're growing, size the bed's growing medium with the Garden Soil Calculator or plan your indoor sowing schedule with the Seed Starting Date Calculator.