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Enter your dimensions for a custom cut list, shopping list, soil estimate and cost — then lay out what you'll actually plant, square foot by square foot.
← Back to the full build guideStandard lumber dimensions differ from their labeled size. A "2x6" actually measures 1.5 inches thick by 5.5 inches tall. A "4x4" post is actually 3.5 inches square. This calculator uses the actual dimensions for all measurements.
The short side boards are cut shorter than the bed's exterior width because they fit between the long side boards. The formula is: short side length = (width in inches) minus 3 inches (1.5" per long board × 2). This gives you the correct finished exterior dimension.
Corner post length includes extra material below the bottom board that gets buried in the ground for anchoring. Taller beds use proportionally longer posts for stability.
Soil volume is calculated from the interior dimensions and rounded up. We use a 60/30/10 mix of topsoil, compost, and peat moss (or coconut coir) — the same recipe recommended in our build guide.
The planner divides your bed into one-foot squares, then fills each one according to how far apart that crop actually needs to be. The spacing numbers come from Colorado State University Extension's block-style guidance for raised beds — CMG GardenNotes #713 and #721, with herb sizes from #731. Density is derived from the spacing rather than guessed: plants per square foot = 144 ÷ (spacing in inches)², rounded down.
That math is deliberately looser than the square-foot-gardening charts you'll find online. Extension spacing assumes each plant reaches mature size, so a tomato gets 24 inches — four squares, not one — peppers get 15 inches, and broccoli 18. Crowding those crops doesn't just cost you elbow room, it costs you the harvest. Small, fast crops stay dense because they genuinely are: carrots and radishes at 2–3 inches really do give you sixteen per square.
Crops that need more than one square (tomatoes, peppers, eggplant, zucchini) only count a plant once you've given them the full footprint, and the plan tells you when you're short. Vining crops — pole beans, peas, cucumbers — assume a trellis, which is what lets them sit at 4- to 6-inch spacing along a single row. Partial feet are left out of the grid, so a 7.5-foot bed plans as seven squares with a six-inch strip to spare.
Don't know your frost date? Our planting calendar by ZIP code looks it up from NOAA climate normals and builds a full sowing schedule around it.
Planting dates work backward and forward from your average last spring frost: cool-season crops go in three to four weeks before it, warm-season crops two weeks after. Harvest windows add each crop's typical days to maturity. Your local frost date is the one number that makes all of it accurate, so it's worth looking up.
The plan also flags two things people learn the hard way: tall crops planted on the south side that shade everything behind them, and neighbors that genuinely don't get along, like onions next to beans.