Gardening Calculators

Gardening and landscaping math is dominated by volume and area calculations: how many cubic yards of mulch for a flower bed, how many pounds of grass seed for new lawn coverage, how many bags of soil for a raised bed, and how much fertilizer for a given lawn size. Getting these numbers right saves money and time — and getting them wrong usually means a second trip to the garden center.

The mulch and soil calculators convert bed dimensions into cubic feet, cubic yards, or bags. Mulch is most commonly sold by the cubic yard from landscape suppliers or by the 2-3 cubic foot bag at retail; we provide both. Standard mulch depth is 2-4 inches for established gardens, with 3 inches being the common recommendation that suppresses weeds without smothering plant roots. The raised bed soil calculator handles the same math but with the typical raised-bed depth of 8-12 inches.

The grass seed calculator uses standard application rates (typically 6-8 lbs per 1,000 sq ft for cool-season grasses like Kentucky bluegrass, 3-5 lbs for warm-season grasses like Bermuda, and higher rates for overseeding repair). It accounts for whether you're starting new lawn or overseeding existing.

Fertilizer calculations convert lawn size to fertilizer quantity based on the N-P-K rating on the bag and the target application rate (commonly 1 lb of nitrogen per 1,000 sq ft per application). The compost calculator handles similar math for soil amendment.

The plant spacing calculator handles the practical question of how many plants you need given a planting area and the recommended spacing for the species. Spacing values come from common nursery references; specific cultivars may vary slightly.

Coverage rates use industry-standard defaults (NRCS extension service rates for fertilizer, university extension service grass-seed rates, garden-industry mulch and soil rates). For specific products, the bag will list manufacturer-recommended application rates that may differ from our defaults. For commercial-scale landscaping or sod-farm work, work with a licensed agronomist who can run a soil test.