Mulch Calculator
Estimate the volume and cost of mulch needed for your landscaping project. Enter the area dimensions and desired depth to get cubic yards, number of bags, and estimated cost.
Mulch is sold by volume — usually cubic yards from a landscape supplier, or in cubic-foot bags from a garden center. Estimating the right amount before you order saves the two most common mistakes: showing up with not enough and making a second trip, or ordering twice what you needed and having a pile sitting in the driveway.
This calculator converts your bed dimensions and desired depth into cubic yards, number of standard bags, and a cost estimate. Enter the length, width, and depth of the area you want to cover; the calculator returns the volume in both cubic yards (for bulk delivery) and in standard 2-cubic-foot bags.
The right depth depends on the mulch type and bed: 2 inches for fine mulches (shredded leaves, pine fines), 3 inches for medium textures (most bark mulches), 4 inches for coarse materials (large bark nuggets, wood chips). Mulch decomposes and settles over time, so most beds need a thin refresh annually rather than complete replacement.
Inputs
Recommended: 2-4 inches for most beds
Results
Cubic Yards
1.11
Bags (2 cu ft)
15
Estimated Cost
$38.89
Material Breakdown
| Measurement | Value |
|---|---|
| Area | 120 sq ft |
| Depth | 3 inches |
| Volume | 30.0 cubic feet |
| Cubic Yards | 1.11 |
| Standard Bags (2 cu ft) | 15 bags |
| Large Bags (3 cu ft) | 10 bags |
| Estimated Cost (bulk) | $38.89 |
Formula
How to use this calculator
- Measure the length and width of the bed in feet. For irregular shapes, break into rectangles and calculate each piece separately, then sum.
- Choose your mulch depth. 2 in for fine mulches, 3 in standard, 4 in for coarse — never more than 4 in (it suffocates roots).
- Enter a price per cubic yard. Bulk-delivered mulch typically runs $25–50/yd; bagged is more expensive per cubic foot.
- Compare bulk vs bagged: anything over about 1 cubic yard usually pencils out cheaper bulk-delivered, even with delivery fee. Under a cubic yard, bags are easier to handle.
- For complete coverage with mature plants in the way, add 5–10% for waste.
Worked examples
Foundation bed
30 ft × 4 ft strip around the front of a house, 3 in deep. Volume: (30 × 4 × 3) / 324 = 1.11 cubic yards Bulk at $35/yd: $39. Bagged at $4/bag (2 ft³): ~$60 for 15 bags. For under a cubic yard, the bagged convenience often outweighs the cost.
Large backyard project
Front bed: 25 × 6, depth 3" → (25 × 6 × 3)/324 = 1.39 yd³ Side bed: 40 × 4, depth 3" → 1.48 yd³ Back bed: 20 × 8, depth 4" → 1.98 yd³ Tree rings (3 trees): 8 × 8 each, depth 3" → 3 × 0.59 = 1.78 yd³ Total: ≈ 6.6 cubic yards. At $30/yd bulk delivered: $198. Bagged at $4/bag would cost ~$355 — bulk delivery is a clear win at this scale.
When to use this calculator
Use this for any landscaping project involving mulch, wood chips, or similar loose material. The same math applies to gravel, decomposed granite, or rubber mulch — just substitute the price.
Typical project rules: - New beds: deeper layer (3–4 inches) to suppress weeds - Established beds: refresh 1–2 inches annually - Around trees: 2–3 inches in a ring 2–3 feet from the trunk, NEVER touching the trunk ("mulch volcano" rot) - Vegetable beds: 1–2 inches of fine mulch (pine fines, leaf mold)
Color-enhanced mulches (dyed black, brown, red) typically cost 20–40% more than natural and fade in 3–6 months in full sun.
Common mistakes to avoid
- Piling mulch against tree trunks. The "mulch volcano" causes rot and pest entry. Leave 2–3 inches of clearance.
- Going deeper than 4 inches. Suffocates roots and prevents water penetration.
- Forgetting that 1 yd³ = 27 ft³, not 9. A common error doubles or triples the bag estimate.
- Not accounting for compaction. Mulch settles 25–30% in the first 6 months. The fluffed-up pile in the driveway looks bigger than it really is.
- Mixing fresh wood chips into bed soil. Decomposing wood ties up nitrogen; use chips on top only.
Frequently Asked Questions
Sources & further reading
- Mulching landscape plants — University of Minnesota Extension