Plant Spacing Calculator (Plants Per Bed)
This tool was built by Serge (MSc) using established science and government sources. My academic background covers plant biology, environmental biology, and biogeochemistry. My tools are for educational purposes and give practical guidance, not professional advice.
Planting too close is one of the quietest ways to lose a crop, since crowded plants compete for light and air and fall to disease. This calculator works out how many plants fit a bed at a given spacing, and how many you fit per square foot. Enter your bed size and the spacing from your seed packet, and it does the layout maths for you.
Plants that fit this bed:
Plants per square foot:
This uses simple grid spacing. Follow the packet spacing, since crowding cuts yield and airflow.
How this works
I divide the bed length by the plant spacing to get how many plants fit along the length, then do the same for the width, and multiply the two. This is a square grid layout, the same idea behind square-foot gardening. For example, at 6 inch spacing you fit 4 plants across a 24 inch width, and 4 down, giving 16 in that area.
Understanding your result
The total is how many plants the bed holds at the spacing you entered. The per-square-foot figure is handy for square-foot gardening, where small plants like radishes go 16 per square, medium plants like lettuce 4 per square, and large plants like peppers 1 per square. If a crop is prone to disease in humid air, lean toward the wider end of its spacing.
Important limitations
This assumes an even grid and the same spacing in both directions. Some crops use different row and in-row spacing, and vining plants trained up a trellis fit more tightly than sprawling ones. It also does not leave room for paths, so for a large plot subtract your walkways first.
Scientific basis
The spacing figures and square-foot layout behind this tool come from university extension services, the public gardening advice arm of the land-grant university system:
- University of Florida IFAS Extension — Square Foot Vegetable Planting Guide
- University of Maryland Extension — Soil to Fill Raised Beds
Related reading
My soil volume calculator works out how much soil to fill the same bed, and my guides on planting cover getting seeds started. My articles on flowers and vegetables give spacing for specific plants.
This calculator is for educational purposes and general guidance only. It is not professional horticultural advice. Always follow the spacing on your seed packet for the specific variety.