Seed Spacing Calculator
Proper plant spacing improves air circulation, reduces disease pressure, and ensures every plant has enough nutrients and light. This calculator tells you how many plants fit in a single row and, optionally, how many total plants fill a rectangular bed when you also know the row spacing. Enter the row length and plant-to-plant spacing in inches. The tool converts everything to consistent units, performs integer division, and adds the starting plant. Results match recommendations from USDA Cooperative Extension planting guides.
Seed spacing formula
Plants per row = floor(Row length (in) / Plant spacing (in)) + 1
Rows in bed = floor(Bed width (in) / Row spacing (in))
Total plants = Plants per row x Rows in bed
The +1 accounts for the plant at the very start of the row. If spacing does not divide evenly, the last gap is smaller, so you still fit one plant at position 0.
Common spacing guidelines
- Radishes, carrots: 2 to 3 inches between plants, 6 to 12 inches between rows.
- Lettuce, spinach: 6 to 8 inches between plants, 12 inches between rows.
- Beans, peas: 4 to 6 inches between plants, 18 to 24 inches between rows.
- Peppers, eggplant: 18 inches between plants, 24 to 30 inches between rows.
- Tomatoes, squash: 24 to 36 inches between plants, 36 to 48 inches between rows.
Seed spacing calculator: frequently asked questions
How do I calculate the number of plants per row?
Divide the row length by the spacing between plants, then add 1 for the plant at the start of the row. For example, a 10-foot row with 6-inch spacing holds (10 / 0.5) + 1 = 21 plants. This calculator does the conversion for you.
How do I figure out how many rows fit in a bed?
Divide the bed width by the row spacing (center to center). A 4-foot-wide bed with 12-inch row spacing holds 4 rows. Multiply rows by plants per row for the total bed capacity.
Does spacing change for square foot gardening?
Yes. Square foot gardening (developed by Mel Bartholomew) uses a grid where each square hosts a different number of plants depending on final size. Large plants like tomatoes get 1 per square, medium plants like lettuce get 4 per square, and small plants like radishes get 16 per square.
What is the spacing for common vegetables?
Carrots: 3 inches. Lettuce: 6 to 8 inches. Peppers: 18 inches. Tomatoes: 24 to 36 inches. Corn: 12 inches in row, 30 to 36 inches between rows. Refer to your seed packet or USDA Cooperative Extension guides for exact recommendations.
Should I plant closer to compensate for poor germination?
Only if you plan to thin seedlings later. Overcrowding reduces air circulation, encourages disease, and limits root development. Adjust the seed count using the germination rate calculator instead, and thin to proper spacing after germination.
Official sources
- USDA National Institute of Food and Agriculture, Cooperative Extension: nifa.usda.gov.
- USDA Agricultural Research Service: ars.usda.gov.
Reviewed by the CalculatorHub team, edited by James Graham, 15 June 2026. See our methodology.