Mulch Calculator
Enter your garden bed dimensions and desired mulch depth to find out exactly how much mulch to buy — in cubic yards, cubic feet, and number of bags.
Enter bed dimensions (add multiple beds if needed)
Recommended: 2–4 inches for most beds
—
Cubic yards
—
Cubic feet
—
Bags
—
Total area (ft²)
How Much Mulch Do I Need?
Mulch volume equals the bed area multiplied by the desired depth. The result in cubic feet is divided by 27 to get cubic yards (the unit bulk mulch is sold in), and divided by the bag size for bagged mulch counts.
Recommended Mulch Depth
| Application | Depth |
|---|---|
| Flower beds | 2–3 inches |
| Vegetable garden | 2–4 inches |
| Trees and shrubs | 3–4 inches |
| Paths and walkways | 3–6 inches |
| Weed suppression | 4 inches minimum |
Avoid piling mulch against tree trunks (the "mulch volcano" mistake) — keep mulch 2–3 inches away from trunks and stems to prevent rot and pest damage.
Bagged vs. Bulk Mulch
| Purchase type | Unit | Best for |
|---|---|---|
| Bagged mulch | 2 or 3 cu ft bag | Small jobs, easy transport |
| Bulk mulch | Cubic yard | Large jobs, cost savings |
| Mulch delivery | Cubic yard minimum | Very large projects |
A cubic yard of bulk mulch covers roughly:
- 324 sq ft at 1 inch deep
- 162 sq ft at 2 inches deep
- 108 sq ft at 3 inches deep
- 81 sq ft at 4 inches deep
Types of Mulch
- Wood chip / shredded bark — the most common; slow to decompose; good for most ornamental beds
- Cedar / cypress — naturally pest and rot resistant; pleasant scent
- Pine straw — lightweight; acidic as it decomposes (good for azaleas and blueberries)
- Rubber mulch — long-lasting; does not decompose; popular for playgrounds
- Gravel / stone — permanent; low maintenance; no decomposition benefit
Frequently Asked Questions
How often do I need to reapply mulch?
Organic mulch decomposes over time. Most wood chip and bark mulch needs to be topped up every 1–2 years. Check the existing depth in late winter before the growing season and top up to the recommended depth.
Can I put too much mulch down?
Yes. More than 4 inches of mulch can prevent water and oxygen from reaching roots, and can create habitat for pests. Stick to the recommended depths.
Does mulch need to be replaced or just topped up?
Generally, just topped up. The decomposed layer at the bottom improves soil structure and adds nutrients. Rake the old mulch to break up any compacted layer, then add fresh mulch on top.
