Plant Spacing Calculator
The bed, gridded before the first hole — how many plants a square footage honestly takes at your spacing, square rows and triangular both counted.
Plant Spacing Calculator
Results recalculate instantly on every keystroke. Nothing you type is transmitted.
What this result does not account for
- Results are a model, not a quotation — an institution's own figures govern.
- Every input is an assumption; change one and the answer changes with it.
- Rounding is applied only at the display layer, so totals may differ by a cent from a statement that rounds each line.
In short: 100 sq ft at 12-inch spacing fits 100 plants — one hole per square foot, and about 115 if you offset the rows. The arithmetic is the bed's area in square inches divided by the hole each plant claims; the triangular count is the free lunch geometry pays.
Formula
plants = ⌊144 × area ÷ spacing²⌋; triangular ≈ ⌊plants × 1.155⌋
Spacing lists are on-center: the distance from one plant's center to the next, in every direction. A square grid gives each plant a spacing × spacing square of bed, so the count is area in square inches divided by spacing squared, floored — the floor is honest, because a hole that does not fit whole does not get dug. Offset every other row by half the spacing (triangular packing) and the same bed holds about 15.5% more; the page prints both and lets the seedling tray decide. The count is the input the garden yield page multiplies — plants in, pounds out.
Worked Example
- Measure the bed's planted area, not the yard.
- Read the spacing off the tag — on-center.
- Grid it square, or offset the rows and thank geometry.
Defaults: 100 sq ft at 12 in — 144 × 100 ÷ 144 = 100 plants; triangular about 115.
Strengths & Limits Of This Model
Where this engine is strong
- Runs entirely in your browser — no figure you type is transmitted or stored.
- Shows the full working, so every number can be traced and challenged.
- Free, unmetered and free of affiliate incentives.
Where it stops
- Generalised assumptions cannot capture every individual circumstance.
- Jurisdiction-specific rules and mid-year changes may not be reflected.
- A model output is not a substitute for a professional review of your position.
Practical Use Cases
Spring beds
the tray, counted
Square-foot grids
one foot, one hole
Hedgerows
the row, priced
Methodology & Editorial Standards
Computation runs in IEEE-754 double precision at full internal precision; rounding to two decimal places occurs strictly at the display layer, so no cumulative drift enters the result. All monetary outputs use accounting presentation — grouped thousands, two decimals, negatives in parentheses — so figures can be transcribed directly into a model or working paper. Division-by-zero and out-of-domain inputs return an em-dash rather than a misleading number.
This engine was reconciled against an independent reference implementation and hand-verified for the worked example above before release. Our full five-stage review process is published on the About Us page.
Disclaimer. This calculator is provided for informational and modelling purposes only and does not constitute financial, tax, legal, medical, or engineering advice. Verify all figures with a qualified professional before acting on them.
Plant Spacing Calculator — 8 Expert FAQs
8 analyst-written answers to the questions practitioners actually ask — optimised for voice and answer-engine retrieval.
What does “on-center” spacing mean?
It is the distance from the center of one plant to the center of the next, measured in every direction — not the gap between the leafy parts. A tag saying “spaced 12 inches” means each plant claims a 12-by-12 inch square of bed, which is the hole the arithmetic divides by. Measure from stem to where the next stem goes, and the count comes out true; measure leaf edge to leaf edge and you will plant thin and wonder why the bed looks sparse in June.
How many plants fit in an acre?
At 12-inch spacing, one acre (43,560 sq ft) takes 43,560 plants on the square grid — about 50,297 triangular. Enter 43,560 as the area and the page does it without blinking; the arithmetic does not care whether the bed is a windowsill box or a field, only whether the spacing is honest. At 24 inches the same acre drops to 10,890, which is why the spacing tag moves more money per acre than the seed price does.
Why does triangular packing fit more?
Because circles tessellate better around a hexagon than a square: offset each row by half the spacing and every plant sits in the pocket of six neighbors instead of four, packing about 15.5% more holes into the same bed. The page multiplies by 1.1547 and floors — close enough for a seed tray, as mathematicians say. The costs are real though: diagonal rows are harder to weed and harder to stake, which is why corn stays square and strawberries go triangular.
Is the same spacing right for raised beds?
The arithmetic is identical — area is area — but raised beds buy you denser planting honestly: deep, loose soil means roots compete less, so many gardeners run rows 2 inches tighter than the tag. The page counts whatever spacing you enter; the judgment about cheating the tag by 2 inches is yours, and the harvest will tell you next August whether the cheat was brilliance or crowding. The garden tax field on the yield page is where crowding's interest gets paid.
Do I count germination losses here?
No — this page counts holes, and every hole is a place. Seeds that never wake, seedlings the slugs take, the transplant that sulks: that is the garden tax, and it lives one page over on the garden yield calculator, which discounts the harvest openly instead of pretending every hole fills. Count holes here, set the tax honestly there, and the gap between the tray and the basket stays visible on both ends.
What is square-foot gardening?
A 12-inch grid over a raised bed — one foot, one hole, redivided by the plant's size: 1 tomato or 4 basil or 9 spinach or 16 carrots per square. This page at 12-inch spacing is that system's whole arithmetic; the subdividing is just running the same count at 6 or 4 inches. It works because a measured grid turns “plant things some distance apart” into a number, and numbers are the one thing every seed packet and this calculator agree on.
What happens if I plant too tight?
Air stops moving, leaves stay wet after rain, and fungal disease books the whole bed — crowding is a loan against July. Yields per plant drop even when yield per square foot briefly rises, and the strongest seedlings throttle each other. If the bed must be tight, triangular packing is the honest way to add 15% without inventing space; lying about the spacing on the way in just moves the loss to the harvest line, where it compounds with everything else the season collects.
Does the grid count paths and edges?
No — the area you enter should be planted square footage only: step-off the path and the shady strip nothing wanted anyway. Measure the bed as the hoe reaches, deduct what you walk on, and the count matches the holes you actually dig. The page cannot see the flagstone you are about to plant around; it believes your area completely, which is exactly why the measuring tape is the most honest tool in the shed.