I've got 1,200 square feet of beds to mulch at 3 inches.

Mulch: 1,200 sq ft × 0.25 ft (3 in.) = 300 cu ft ÷ 27 = 11.1 cu yd. Order 12 cu yd (round up for settling/spillage).

Topsoil: 20 ft × 30 ft = 600 sq ft × 0.333 ft (4 in.) = 200 cu ft ÷ 27 = 7.4 cu yd. Order 8 cu yd screened.

Notes:

• Confirm material is “screened topsoil,” not fill or compost blend.
• Spread topsoil, lightly compact, then mulch.
• No code citations needed; this is estimating math.

To calculate the mulch and topsoil needed:

1. Mulch for 1,200 sq ft at 3 inches deep: Convert depth to feet: 3 in = 0.25 ft Volume = 1,200 sq ft × 0.25 ft = 300 cubic feet Convert to cubic yards: 300 ÷ 27 = 11.11 cubic yards → Order 12 cubic yards (round up to account for settling and spillage).

2. Screened topsoil for 20 ft × 30 ft area at 4 inches deep: Area = 20 × 30 = 600 sq ft Depth = 4 in = 1/3 ft ≈ 0.333 ft Volume = 600 × 0.333 = 200 cubic feet Convert to cubic yards: 200 ÷ 27 ≈ 7.41 cubic yards → Order 8 cubic yards (round up for compaction and waste).

Notes:

• Mulch and topsoil settle; always order 10–15% extra.
• Screened topsoil is free of rocks/debris — ideal for planting beds.
• No license needed for material calculation, but if grading or drainage work is involved, check local codes (e.g., IRC R405.1 for foundation drainage).
• Confirm product density with supplier — some blends vary slightly.

Final Answer:

• Mulch: 12 cubic yards
• Topsoil: 8 cubic yards