Enter your vegetable row measurements and matching spacing to find how many seeds, final plants, or transplant positions you need.
Check that this wording matches the spacing on your packet or planting guide.
Rounded up so the packets contain at least the calculated number of seeds.
Table of contents
How to use our Vegetable Seed Calculator
- Choose the task under "What are you counting?": "Seeds to sow now," "Final plants after thinning," or "Transplant positions."
- Measure the usable planting length of one row and enter it in "Length of each row (ft)."
- Enter the number of rows with that same length in "Number of equal-length rows."
- Copy the spacing along one row from your seed packet or planting guide into "Spacing along each row (in)." Make sure it matches the task you selected.
- For direct sowing, open "Advanced options" if you want to account for expected germination, add an extra seed reserve, or calculate packets to buy.
- Select "Calculate." Read the first result as your needed seeds or planting positions, then check "Spacing used for this count" before planting or buying seeds.
- If the answer is 0, the row is shorter than one spacing interval. Use a different row length or spacing only if it agrees with your crop instructions.
Definitions
In-row spacing: The distance from one seed or plant to the next in the same row. Planting charts commonly list it separately from spacing between rows. [1]
Seed-sowing spacing: The spacing used when placing seeds in the garden.
Final spacing after thinning: The distance left between plants after extra seedlings are removed.
Germination rate: The percentage of seeds expected to sprout. A lower entered rate raises the direct-sow seed count.
Seed reserve: An extra percentage of seeds added after the germination adjustment, based on your own plan.
Common mistakes and quick fixes
Mistake: Entering the distance between rows instead of the distance between seeds or plants in one row.
Fix: Enter only the spacing along a row. This calculator does not use between-row spacing.
Mistake: Selecting "Seeds to sow now" while entering the final spacing after thinning.
Fix: Match "What are you counting?" to the spacing wording on the packet or planting guide.
Mistake: Using germination or reserve settings for a final-plant or transplant plan.
Fix: Those adjustments apply only to direct-sown seeds. Final plants and transplants use the planting-position count.
Mistake: Averaging rows with different lengths.
Fix: Calculate each group of equal-length rows separately. Unused space at the end of one row cannot be combined with another row.
Mistake: Rounding packet purchases down.
Fix: Use the displayed packet count, which rounds up so the packets contain at least the needed number of seeds.
Limitations & Key Assumptions / Boundary Conditions
- This calculation is for straight, equal-length rows. Calculate rows with different lengths as separate groups.
- It counts evenly spaced positions along rows. It does not model rectangular grid beds, broadcast sowing, dense baby-leaf planting, or intercropping.
- For direct sowing, a blank germination rate means 100% and a blank reserve means 0%. Actual emergence can differ from an expected germination rate under garden conditions.
- Use crop-specific packet or planting-guide instructions for spacing, thinning, and planting depth. The calculator does not choose suitable spacing for a crop.
- The packet estimate depends on the seed quantity stated for the exact packet. Packet quantities can vary by variety and seller.
Methodology
Row count method
The calculator changes each row length from feet to inches, divides by the entered in-row spacing, and rounds down within each row. This keeps leftover space at the end of one row from creating a position in another row.
positions_per_row = floor(row_length_ft * 12 / in_row_spacing_in)
base_positions = positions_per_row * number_of_rows
For "Final plants after thinning" and "Transplant positions," base positions are the main answer. For "Seeds to sow now," a blank germination rate is treated as 100% and a blank reserve as 0%. If either optional setting is entered, the seed count rounds up.
seeds_needed = ceil(base_positions / germination_fraction * (1 + reserve_fraction))
If "Seeds per packet" is entered, the calculator also rounds the purchase count up to a whole packet.
packets_to_buy = ceil(seeds_needed / seeds_per_packet)
Mini-example
For two 10 ft rows at 3 in spacing, each row is 120 in long and fits floor(120 / 3) = 40 positions. That makes 80 base positions. With 80% germination and a 10% reserve, the direct-sow count is ceil(80 / 0.80 * 1.10) = 111 seeds. At 50 seeds per packet, ceil(111 / 50) = 3 packets.