What this plant spacing calculator does — and its lane
This tool handles discrete-plant spacing geometry: how many individual plants, seedlings, bulbs, shrubs or trees fit a given area at a given spacing, and the matching density figures — plants per square foot, per square metre, per acre and per hectare. It is the tool for “how many do I buy?” It is not a seed-by-weight tool (that is the grass seed calculator), not a nutrient tool (the fertilizer calculator) and not a volume tool (the soil calculator). The one job here is counting plants from spacing, and getting the square-versus-triangular difference right.
The real friction this fixes: most quick answers stop at “area divided by spacing,” which silently assumes a square grid and ignores the roughly 15% extra you get from offset rows — and they rarely show plants per square foot, per acre and per bed in one place. This shows all of them, in either layout, with the formula on the page.
How many plants per square foot?
For an even, square grid, the number of plants per square foot is 144 divided by the square of the spacing in inches. There are 144 square inches in a square foot, and each plant on a square grid claims a square of side equal to the spacing.
plants per sq ft = 144 ÷ (spacingin)² = 1 ÷ (spacingft)²
plants in a bed = bed area ÷ (in-row spacing × row spacing)
So 12-inch spacing gives 144 ÷ 144 = 1 plant per square foot, 6-inch spacing gives 144 ÷ 36 = 4, 4-inch spacing gives 144 ÷ 16 = 9, and 3-inch spacing gives 144 ÷ 9 = 16. Those familiar grid numbers used in intensive, square-foot-style gardening are simply this division — the calculator computes them rather than reading them off a chart, so any spacing works, including in-between values like 5 or 8 inches.
How many of each vegetable fit per square foot
The table below lists typical, editable spacings for common crops (widely published horticultural ranges, given as a starting point) and the plants-per-square-foot each spacing produces from the same 144 ÷ spacing² math. Treat them as a guide for intensive grid spacing, not a rule — actual spacing varies by variety, climate and how big you let plants grow, so check the packet. Pick a crop in the calculator to load its spacing, then edit it freely.
| Crop | Typical spacing | Per square foot |
|---|---|---|
| Carrot | 2–3 in | 16–36 |
| Radish | 2 in | 36 |
| Onion | 3–4 in | 9–16 |
| Beet | 3 in | 16 |
| Spinach | 3 in | 16 |
| Pea | 2–3 in | 16–36 |
| Garlic | 4 in | 9 |
| Bush bean | 4–6 in | 4–9 |
| Lettuce | 6–8 in | 2–4 |
| Pole bean | 6 in | 4 |
| Basil | 6 in | 4 |
| Corn | 6–12 in | 1–4 |
| Zinnia | 6–9 in | 1–4 |
| Tulip bulb | 4–6 in | 4–9 |
| Strawberry | 12 in | 1 |
| Cucumber | 12 in | 1 |
| Broccoli | 12–18 in | ¼–1 |
| Cabbage / kale | 12–18 in | ¼–1 |
| Pepper | 12–18 in | ¼–1 |
| Zucchini / squash | 18–24 in | <¼ |
| Tomato | 18–24 in | <¼ |
Where a crop needs more than one square foot each (tomato, squash), the “per square foot” figure is below one — that simply means one plant spans several squares. The bed-area output handles those cleanly by counting whole plants.
Plant spacing in rows and beds
For a planted bed or field, each plant claims a rectangle equal to its in-row spacing times its between-row spacing, so the count is the area divided by that rectangle. A single row holds floor(row length ÷ spacing) + 1 plants — the “+1” is the plant at the very start of the row, the one most calculators forget. The bed mode lets you enter length × width or row length × number of rows, in feet/inches or metres/centimetres.
Square vs triangular (offset) spacing
In a square layout, plants line up in a grid and each occupies spacing × spacing. In a triangular (also called offset, staggered, diamond or hexagonal) layout, every other row shifts by half the spacing, so the rows nest closer together. That packs roughly 15% more plants into the same area at the same centre-to-centre distance — the density is multiplied by about 1.155 (equivalently the row spacing is multiplied by 0.866, the height of an equilateral triangle). Triangular is common in landscaping, ground cover and hedges; square is easier to lay out and to weed or harvest between.
Plants and trees per acre
For orchards, windbreaks, field crops and reforestation, work in plants or trees per acre. An acre is 43,560 square feet, so:
plants/trees per acre (square) = 43,560 ÷ (s1ft × s2ft)
triangular = 43,560 ÷ (s1ft × s2ft × 0.866) ≈ square × 1.155
per hectare = per acre × 2.4711
For example, trees on a 20 ft × 20 ft square spacing give 43,560 ÷ 400 = about 109 per acre; the same spacing offset (triangular) gives about 126 per acre. Enter a total area in acres to turn the density into a whole-field plant count.