Seed Spacing Calculator
Calculate how many seeds to plant and at what spacing for garden beds. Enter values for instant results with step-by-step formulas.
Reviewed by Daniel Agrici, Founder & Lead Developer
Formula
Plants Per Row = floor((Row Length × 12) / Spacing) + 1 | Total = Plants Per Row × Rows
Convert row length to inches, then divide by the recommended spacing between plants (found on the seed packet). Add 1 because the first plant is placed at the very start of the row (position 0), before any spacing gaps begin. Multiply by the number of parallel rows to get the total plant count, and add roughly 10% extra seeds beyond that to account for germination failure, especially for direct-seeded crops like carrots and beets that are commonly thinned after sprouting.
Worked Examples
Example 1: Tomato row garden bed
Problem:A 20 ft row, tomatoes spaced 24 inches apart, planted in 3 parallel rows
Solution:Row length in inches = 20 × 12 = 240\"\nPlants per row = floor(240 / 24) + 1 = 10 + 1 = 11\nTotal plants = 11 × 3 rows = 33
Result:33 tomato plants total (11 per row across 3 rows)
Example 2: Carrot direct-seeding with germination buffer
Problem:A single 15 ft row of carrots spaced 3 inches apart — how many seeds should be purchased?
Solution:Row length in inches = 15 × 12 = 180\"\nPlants per row = floor(180 / 3) + 1 = 60 + 1 = 61\nSeeds to buy (10% germination buffer) = ceil(61 × 1.1) = 68
Result:61 final plants | buy 68 seeds to account for germination loss
Frequently Asked Questions
How do I calculate plant spacing for maximum yield?
Square foot gardening assigns each plant a grid space: 1 per square foot for tomatoes and peppers, 4 for lettuce, 9 for beets, 16 for carrots and radishes. Traditional row spacing is wider to allow cultivation equipment. Intensive spacing increases yield per area but requires more fertile soil and consistent watering.
Reviewed by Daniel Agrici, Founder & Lead Developer · Editorial policy