Square Foot Garden Plants Calculator
Calculate how many plants fit in a square-foot garden grid based on bed size and plants-per-square-foot for each crop.
How to use this tool
- Enter your grid dimensions in feet (standard is 4×4 ft).
- Enter the plants-per-square-foot for your chosen crop.
- The calculator shows total grid squares and the number of plants to buy.
Plan your square-foot garden to grow more food in less space with perfect spacing.
Formula
Grid squares = Length (ft) × Width (ft)
Total plants = Grid squares × Plants per square foot
Grid squares are rounded to the nearest integer; total plants is an exact product.
How it works
This calculator applies the square-foot gardening method pioneered by Mel Bartholomew, which divides a raised bed into a grid of one-square-foot cells and assigns a fixed planting density to each cell based on mature plant size. Multiplying the total number of cells by the per-cell density gives the maximum plant count for a given crop.
The plants-per-square-foot value depends on the crop: large plants such as tomatoes or peppers occupy one cell each (1 plant/ft²), medium plants such as lettuce use 4, and small plants such as radishes or carrots use up to 16. Mixing densities across cells requires tracking each section separately.
Worked example
Worked example
- Bed dimensions: 4 ft × 4 ft. Crop: spinach at 4 plants per square foot.
- Grid squares = 4 × 4 = 16 square feet.
- Total plants = 16 × 4 = 64 plants.
Total grid squares: 16 — Total plants: 64
Key terms
- Square-foot gardening
- An intensive raised-bed method that divides growing space into 1 ft² sections, each planted to a specific density to maximise yield in small areas.
- Plants per square foot
- A crop-specific density value determined by the plant's mature spread; ranges from 1 (large fruiting crops) to 16 (small root vegetables).
- Raised bed
- A contained planting area filled with amended growing medium, typically 6–12 inches deep, allowing closer plant spacing than in-ground rows.
- Succession planting
- Replanting a finished cell immediately after harvest with a different or the same crop to extend seasonal productivity.
Frequently asked questions
- How many plants per square foot?
- Square-foot gardening uses a simple guide: 1 plant per sq ft for large crops (tomatoes, peppers), 4 for medium (lettuce, basil), 9 for small (spinach, beets), and 16 for tiny crops (carrots, radishes).
- What is square-foot gardening?
- Developed by Mel Bartholomew, square-foot gardening (SFG) divides a raised bed into 1-ft² squares, each planted intensively. It reduces water use, weeding, and wasted space compared to row gardening.