ToolNestFree Seed Spacing Calculator
Last updated: October 25, 2026
Quick answer: A seed packet says 'space 2 inches apart' and 'rows 12 inches apart' - but how many seeds does that actually mean for your garden, and how many packets do you need to buy? This free seed spacing calculator answers both: pick your crop (25 common vegetables with real default spacings), your row length or your bed size, and your germination rate, and it returns seeds per row, seeds to sow (adjusted for germination, so a weak batch does not leave gaps), plants after thinning, and packets to buy. Everything runs in your browser; no signup, no app.
Worked example: carrots at 2-inch in-row spacing in a 10-foot row give 120 ÷ 2 = 60 seeds per row before germination. At 80% germination you sow 60 ÷ 0.80 = 75 seeds, and after thinning you keep 60 plants. With 100 seeds per packet, one packet covers that row.
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How to Use the Seed Spacing Calculator
- Pick your crop first: the calculator fills in that vegetable's usual in-row spacing (distance between plants in a row) and row spacing (distance between rows) - carrots at 2 inches in-row and 12 inches between rows, tomatoes at 24 and 36, and so on for 25 common vegetables. Change either spacing if your packet says something different; your numbers always win over the defaults.
- Choose how to plan: row length + number of rows for a traditional row garden (for example 3 rows of 10 feet), or bed area for a raised bed (for example an 8 x 4-foot bed). In bed mode the calculator works out how many rows fit across the bed width from your row spacing, and uses the bed length as the row length.
- Enter your germination rate - the percentage of seeds that typically sprout. Seed packets often print it, and 80% is a reasonable default for fresh seed; old seed runs lower. This is the step most spacing tools skip, and skipping it is how a row ends up with gaps: at 80% germination, 60 final plants need 75 seeds sown, not 60.
- Enter seeds per packet from your packet (or the listing, if you buy online). Packet sizes vary wildly - a packet of lettuce may hold 500 seeds, a packet of squash only 10 - so the packets-to-buy number is only honest if this number matches your actual packet.
- Press Calculate seeds and read four numbers: seeds per row at final spacing, seeds to sow (the total, adjusted upward for germination), plants after thinning (the final stand, once extras are thinned out), and packets to buy (seeds to sow divided by seeds per packet, rounded up). The layout line also states rows x plants per row so you can picture the bed.
- Sow the seeds to sow number, evenly spaced, then thin once seedlings have their first true leaves: snip (do not pull) the extras down to the in-row spacing, leaving the strongest seedling at each spot. If the packets number is more than you planned to buy, check whether a bigger packet or a second variety is cheaper than two small packets of the same seed.
Why Use Our Seed Spacing Calculator?
- 25 vegetables with real default spacings - carrots, lettuce, beans, tomatoes, squash and 20 more, each starting at the in-row and row spacing gardeners actually use, instead of a corn-only or potato-only tool that cannot answer a general garden question.
- Germination-rate adjustment on every result - seeds to sow are divided by the germination rate, so an 80% batch and a 95% batch give genuinely different shopping lists. Most small spacing tools ignore germination entirely and understate the seed you need.
- Two planning modes - row length + row count for traditional rows, and bed length x bed width for raised beds, where the row count is derived from the bed width and row spacing instead of guessed.
- Packet math, not just seeds per foot - the result converts seeds to sow into packets to buy using your packet's actual seed count, rounded up, so the answer ends at the checkout instead of halfway through the arithmetic.
- Thinning kept separate from sowing - the result shows both the seeds to sow and the plants you keep after thinning, so it is clear why you sow more than you keep, and by exactly how much.
- Spacing overrides on every crop - the crop defaults are a starting point, not a lock: change in-row or row spacing to match your packet, your variety, or your soil, and every output updates.
Common Use Cases
- A first vegetable garden in raised beds: Two 8 x 4-foot beds, carrots in one and lettuce in the other: bed mode gives 4 carrot rows (48 inches / 12-inch row spacing) of 8 feet, 8 / 2-inch spacing = 48 seeds per row, 192 seeds at final spacing, 240 to sow at 80% germination - and 3 packets of 100. The lettuce bed, at 8-inch in-row spacing, needs far fewer seeds for the same bed, which is the kind of comparison that stops a beginner buying ten packets of everything.
- Filling a long row garden before spring: Six 25-foot rows of bush beans at 3-inch in-row spacing: 300 inches / 3 = 100 seeds per row, 600 at final spacing, 750 to sow at 80% germination. Beans are usually sold in packets of 50-100, so the packets number (8-15 depending on the packet) is the number that actually decides the order - and the reason this calculator ends at packets, not seeds per foot.
- Succession lettuce through the summer: One 10-foot row of lettuce every three weeks: 120 / 8 = 15 plants per row, 19 seeds to sow at 80% germination, one packet of 200+ seeds covering the whole season's successions. Running the calculator once per sowing, rather than once for the season, keeps each batch right-sized instead of one giant spring sowing that bolts all at once.
- Checking whether one packet is enough: A packet of squash holds 10 seeds, and squash wants 36-inch spacing: a 12-foot row holds 4 plants, 5 seeds to sow at 80% germination, so one packet covers two rows with seed to spare. The same check on carrots (100-seed packet, 2-inch spacing) shows one packet covers a single 10-foot row with 25 seeds left - two very different answers from the same 'one packet' assumption.
Seed Spacing Calculator vs Alternatives
- Seed-company and seed-retailer calculators (several of the sites ranking today): They know their own varieties well, and their spacing defaults match the packets they sell. But they are built around one seller's catalog, and several are narrow - a corn calculator, a potato calculator, a population tool - rather than a general garden tool, so a mixed vegetable garden needs several of them. This page covers 25 vegetables in one place, with spacing you can override to match any packet, from any seller.
- Small garden calculator sites (the general tools ranking today): They answer the seeds-per-foot question cleanly, and for a single row that is often enough. What they typically do not do is adjust for germination, work in bed-area mode, or convert the answer into packets to buy, so the gardener still finishes the arithmetic by hand. This page does all three in one result: seeds per row, germination-adjusted seeds to sow, plants after thinning, and packets.
- University and government garden tools (including the .gov tool ranking today): Their spacing figures are authoritative, and this page's defaults follow the same standard spacings they publish. But a reference table or a population-focused tool is not a planner: it does not take your row length, your germination rate, and your packet size and return a shopping list. This calculator is the step that turns those standard spacings into your garden's numbers.
- Seed packet charts and planting guides: A packet back or a planting chart gives you the two spacings and sometimes a seeds-per-foot figure, and that is genuinely useful - it is where this page's defaults come from. A chart cannot do your arithmetic, though: for 3 rows of 10 feet at 80% germination, or an 8 x 4-foot bed, you still need a calculator, and this page is that calculator next to the chart.
Most seed spacing tools answer one narrow question - seeds per foot for one crop, or a population for one field. This page answers the whole garden question: pick any of 25 vegetables, plan by rows or by bed, adjust for germination, and finish with plants after thinning and packets to buy - the numbers you actually need before you order seed.
Frequently Asked Questions
How do you calculate seeds per row?
Seeds per row = row length in inches divided by in-row spacing in inches. A 10-foot row is 120 inches, so carrots at 2-inch spacing need 120 / 2 = 60 seeds per row at final spacing. For the whole planting, multiply by the number of rows, then divide by the germination rate (as a decimal) to get seeds to sow: 60 seeds at 80% germination means 60 / 0.80 = 75 seeds sown. The calculator above does this for any crop, row length, and germination rate.
What is the difference between row spacing and in-row spacing?
In-row spacing is the distance between plants along one row - 2 inches for carrots, 24 inches for tomatoes. Row spacing is the distance between one row and the next - 12 inches for carrots, 36 inches for tomatoes. In-row spacing decides how many plants fit in a row; row spacing decides how many rows fit in a bed and how much room you have to walk, weed, and harvest between them. Confusing the two is the most common spacing mistake: using row spacing along the row would plant carrots 12 inches apart and waste most of the row.
How does germination rate change how many seeds to sow?
Divide by it. If you want 60 final plants and your seed germinates at 80%, sow 60 / 0.80 = 75 seeds; at 50% (old seed), sow 60 / 0.50 = 120 seeds. That is why this calculator asks for a rate and why tools that skip it understate your seed: they assume every seed sprouts, and in real soil 10-30% typically do not. Check the packet or the supplier listing for the tested rate, and drop it for seed more than a year old.
How does seed spacing work in square-foot gardening?
Square-foot gardening replaces rows with a grid: one 12 x 12-inch square holds 1 plant at 12-inch spacing, 4 at 6-inch spacing, 9 at 4-inch spacing, or 16 at 3-inch spacing (spacing = 12 / plants-per-side, squared). Carrots at 2-inch spacing would be 36 per square in theory, but in practice square-foot guides plant carrots 16 per square (3-inch grid) because 2-inch carrots are hard to thin and harvest. Use this calculator's row mode with a 1-foot row length to get the same grid math, then plant that count per square.
What is succession planting, and how does spacing help it?
Succession planting is sowing the same crop in small batches every 2-3 weeks instead of all at once, so harvests keep coming instead of arriving in one glut. Spacing matters because each batch needs its own row length: if one 10-foot row of lettuce feeds you for two weeks, sow a fresh 10-foot row every two weeks rather than 40 feet at once. This calculator's per-row numbers are the batch size - run it once per sowing, not once per season, and add the batches for the season total.
When and how do you thin seedlings?
Thin once seedlings have their first true leaves (the second pair of leaves, which look like the adult plant's leaves, not the smooth seed leaves). Snip the extras at soil level with scissors rather than pulling them - pulling disturbs the roots of the seedling you want to keep. Thin to the final in-row spacing: carrots sown thickly get thinned to 2 inches apart, lettuce to 8 inches. The plants-after-thinning number on this calculator is the count you should be left with, not the count you sow.
How do you work out seed packet math - how many packets to buy?
Packets to buy = seeds to sow (germination-adjusted) divided by seeds per packet, rounded up. Example: you need 75 carrot seeds and the packet holds 100, so 1 packet. But 3 rows of 10 feet at 80% germination need 225 seeds, so 3 packets of 100 - or one larger packet if the supplier sells it. Always round up: a packet cannot be bought in fractions, and running out mid-row is worse than having a few seeds left for next year (most vegetable seed keeps 2-4 years if stored cool and dry).
Should I direct sow or transplant this crop?
Direct sow crops with long taproots or fast growth that dislike root disturbance: carrots, radish, beets, beans, peas, corn, squash, and turnips all go straight into the soil at the spacings on this calculator. Transplant crops that need a long warm season or a head start indoors: tomatoes, peppers, eggplant, broccoli, cauliflower, cabbage, and celery are usually started indoors and planted out at their final spacing - and for those, the plants-after-thinning number is the number of transplants to raise, not seeds to sow in the row. Lettuce, kale, and chard work either way.