Plants counted on the real grid, seed adjusted for the germination you will actually get
A bed holds the plants its grid holds, not the plants its area suggests, and a seed packet’s promise is a laboratory figure. This calculator counts both ways and shows both: the layout count on your spacing (plants at each spacing interval along the row, rows across the bed), the area cross-check beside it, and then the seed arithmetic where germination does its honest work: to finish with N plants at G percent germination you sow N/G seeds, more again if you sow several per station and thin. An optional yield line multiplies by a per-plant figure you supply from your own garden’s history, labelled as yours because no calculator knows your soil.
Disclaimer: This calculator gives estimates for general information only. It is not financial, medical or other professional advice. Germination and yields vary with seed age, storage, soil and season; packet instructions and local extension guidance govern planting practice.
What this calculator does
Two counts of a planting disagree for an honest reason: the area method divides the bed by each plant’s allotted rectangle and suits big fields, while the grid method walks the bed placing plants at the spacing marks and suits the beds people actually plant, where the first plant sits near the edge and the last row either fits or visibly does not. This page leads with the grid (its convention printed in the method) and shows the area figure as the cross-check it is. The seed side then reverses the usual direction: instead of asking how many seeds you have, it asks how many plants you want standing, and divides by germination, because a packet bought for 40 plants at 80 percent germination is a packet of 32 plants wearing a bigger number.
How to use it
- Spacing comes from the packet or the variety’s guidance, at final size. The two distances differ (in-row and between-row) for most vegetables; crowding to fit a count is the one edit this page cannot talk you out of and the yield line will not forgive.
- Germination is the tested figure when you have one. A damp-paper-towel test of 20 seeds gives your lot’s real percentage; packet figures assume fresh seed stored well, and home-saved or old seed earns its own number here.
- Seeds per station trades seed for certainty. Sowing 2 or 3 and thinning to the strongest is insurance priced in seed, rational for cheap seed and precious timing, wasteful for costly hybrids; the field prices both ways because both are legitimate.
- Succession plantings multiply the answer. Lettuce every fortnight is six plantings of the same bed: run the count once and multiply by your successions, rather than planting the season in one heroic weekend.
The method
- Grid count: plants per row = floor(length in inches / in-row spacing) + 1 (a plant at each spacing mark including the start); rows = floor(width / row spacing) + 1; the bed’s count is their product. Area cross-check = bed area / (in-row × between-row spacing), rounded.
- Seed to sow = stations × seeds per station, where stations = grid plants / germination as a decimal, rounded up at the end: the division is done on the plant target, not on the sow count, so thinning plans stay honest.
- Seed weight = seeds to sow / seeds per gram. Yield estimate = grid plants × your per-plant figure, in your unit.
Worked examples
The salad bed. A 10 by 4 ft bed at 12 in in the row and 18 between rows: floor(120/12) + 1 = 11 plants per row, floor(48/18) + 1 = 3 rows, 33 plants standing (the area method’s cross-check says 27, the difference being the edge plants the grid honestly includes). At 85 percent germination, finishing with 33 plants takes ceil(33 / 0.85) = 39 seeds sown singly, and a gram of carrot seed at 800 per gram is twenty such beds: small seed is cheap, which is exactly why thinning plans exist.
The bean row. A single 20 ft row at 6 in: floor(240/6) + 1 = 41 plants, and at bean seed’s size (about 4 seeds per gram) the sowing is weighed in handfuls, not pinches: 41 stations at 90 percent germination is 46 seeds, about 12 g. The contrast between the two examples is the page’s quiet lesson: seed quantity is a spacing and germination story long before it is a shopping story.
Reading your results
Read the grid and area counts as bounds on the same truth: plant the grid count in beds (the edges are real), expect the area count in open field rows (where ends wash out over distance). Read the germination division as the packet’s fine print made visible, and the seed weight as a check on the packet count: packets sold by count suit large seed, packets sold by weight hide their count in the seeds-per-gram figure, and the conversion is printed here so the two packagings can be compared like adults.
Limitations
- The grid convention plants at the very edge. Gardeners who inset the first plant by half a spacing (the other common convention) get one fewer plant per row and row; the area cross-check approximates that layout, and the difference matters only in small beds, where the page shows both so you can choose your own.
- Germination in soil runs below the towel test. Depth errors, crusting, cold and pests all tax emergence beyond the laboratory percentage; the field takes the figure you expect in the ground, and experienced growers shade it down for early sowings.
- Spacing guidance is variety-specific. The numbers on this page are inputs; determinates and indeterminates, bush and pole forms, and cut-and-come-again crops each carry their own, printed on the packet that also governs depth.
- Yield is your figure or nobody’s. The optional line multiplies your per-plant history; it is deliberately not stocked with generic yields, because a guaranteed harvest is a claim no honest page makes about your weather.
Frequently asked questions
How many plants fit in my raised bed?
On the grid: divide each dimension by its spacing, take the whole intervals, add one for the starting plant, and multiply rows by plants per row, which the worked example does for a standard 10 by 4 bed. The popular square-foot approach (one plant per allotted square, or subdivisions of it) is the area method in disguise and lands near this page’s cross-check figure; the difference is edges, and in a small bed the edges are a fifth of the crop, so the grid is the count to plant by.
Why sow more seed than the plants I want?
Because germination is a probability wearing a percentage: at 85 percent, sowing exactly 33 seeds returns about 28 plants, unevenly spaced. Dividing the target by the germination rate restores the expectation, and sowing extra per station then thinning converts the probability into a choice of the strongest seedlings. The arithmetic is the same one nurseries run at scale, and it is why a packet’s seed count and its plant count are never the same number on any honest label.
How do I test my seed’s germination?
Twenty seeds on damp paper towel in a sealed bag somewhere warm; count the sprouted after the packet’s stated days, and that fraction is your percentage for the field here. Below about half, most growers replace the lot for anything time-critical, since thin emergence costs the bed’s uniformity as well as its count. The test costs ten days and twenty seeds, and it converts the germination input from the packet’s hope into your measurement.
What spacing do common vegetables want?
Packet figures govern, but the familiar ranges are: lettuce 8 to 12 in, carrots thinned to 2 to 3, bush beans 4 to 6 in rows 18 apart, tomatoes 18 to 24 in rows 36 apart, peppers 12 to 18, courgettes and squash a yard in every direction and still ambitious. Enter the pair of distances separately where they differ, since the rectangular grid, not the square, is how most crops are actually laid out.
Related calculators
Method: plant counts on the stated edge-inclusive grid with an area cross-check, seed quantities adjusted by entered germination and sowing rate, weights from entered seeds per gram, and yields only from the user’s own per-plant figure. Last reviewed: 15 October 2026.