Square Foot Gardening Calculator
Square Foot Gardening (SFG) divides a raised bed into 1-foot squares, planting 1, 4, 9 or 16 plants per square based on each crop's mature spacing. Enter your bed size and crop plan to get total grid squares, plants per crop, and soil volume.
① Bed Dimensions
Total squares = length × width. Adjust the size to see how many squares remain unplanned.
② Crop Plan
For each crop, enter the number of squares it occupies. Plants per square are computed automatically from spacing (1 / 4 / 9 / 16).
| Crop | Squares | Plants/sq | Total plants |
|---|
Frequently Asked Questions
What is Square Foot Gardening (SFG)?
A dense planting method created by Mel Bartholomew: divide a raised bed into 1-foot squares instead of traditional single rows. Plant 1, 4, 9 or 16 plants per square by mature spacing — space-saving, soil-saving and easy to manage, ideal for small yards and balconies.
Why 1 / 4 / 9 / 16 plants per square?
Based on mature spread: spacing ≥12 in (tomato, cabbage) = 1 plant/sq; 6–9 in (lettuce, spinach) = 2×2 = 4; 4 in (beet, radish) = 3×3 = 9; 3 in (carrot, onion) = 4×4 = 16.
Is 6 inches of soil depth enough?
The standard SFG bed is 6 inches (about 15 cm) deep with Mel's Mix (equal parts compost, peat/coco coir, and perlite). This calculator defaults to 6 inches but you can change it; volume and bag count update automatically.
How is soil volume calculated?
Volume = length(ft) × width(ft) × depth(in)/12. Example: a 4×4 ft bed at 6 in deep = 16 × 0.5 = 8 ft³ ≈ 0.30 yd³ (226 L), needing about 6 bags of 1.5 ft³ soil.