Mulch Calculator
For a 300 sq ft bed at 3" deep, you need 2.78 cubic yards — about 38 bags (2 cu ft). Bulk: $85-140, bags: $114-190.
Mulch Calculator
Enter your project dimensions for instant results.
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How to Calculate Mulch
The formula converts area and depth to cubic yards:
cubic_yards = (length_ft × width_ft × depth_in) / 324
For circular beds: area_sqft = π × radius², then use cubic_yards = (area_sqft × depth_in) / 324
| Depth | Sq ft per Cubic Yard | 2 cu ft Bags per 100 sq ft | 3 cu ft Bags per 100 sq ft |
|---|---|---|---|
| 1″ | 324 | 5 | 3 |
| 2″ | 162 | 9 | 6 |
| 3″ | 108 | 14 | 9 |
| 4″ | 81 | 17 | 12 |
| 6″ | 54 | 25 | 17 |
| Application | Depth | Notes |
|---|---|---|
| Annual refresh (existing beds) | 1-2″ | Top up faded/decomposed layer |
| Standard flower beds | 2-3″ | Most common recommendation |
| New beds (weed suppression) | 3-4″ | Over landscape fabric |
| Playground surfacing | 6-9″ | ASTM F1292 fall height safety |
| Paths / walking areas | 3-4″ | Use hardwood, not pine bark |
Common Mistakes:
- Piling mulch against tree trunks ("volcano mulching") — keep a 3-6" gap around trunks to prevent bark rot
- Applying more than 4" — excessive depth suffocates roots and creates fungal habitat
- Not removing old decomposed mulch before adding new layers year after year — the bed level rises and mulch contacts low branches
- Using dyed mulch near edible gardens — some dyes contain chemicals not rated for food-contact areas
- Buying bags for large projects — over 3 cubic yards, bulk delivery costs 50-70% less
Frequently Asked Questions
How many bags of mulch do I need?
Divide your total cubic feet by the bag size. For 300 sq ft at 3" deep: 300 × 3/12 = 75 cubic feet. That's 38 bags of 2 cu ft mulch or 25 bags of 3 cu ft mulch. Add 5-10% for irregular bed shapes.
How much does a yard of mulch cost?
Bulk mulch costs $30-50 per cubic yard for standard hardwood or pine, $40-65 for dyed/colored mulch, and $45-80 for premium cedar or cypress. Delivery adds $50-100 per load. Bagged mulch works out to $50-80 per cubic yard equivalent.
How deep should mulch be?
2-3 inches for most landscape beds. Existing beds being refreshed need only 1-2 inches. Playground mulch needs 6-9 inches for safety. Never exceed 4 inches in garden beds — deeper mulch suffocates plant roots and harbors pests.
When is the best time to mulch?
Mid-to-late spring after soil warms is ideal — mulch insulates soil temperature, so applying too early keeps soil cold. Fall mulching (October-November) protects roots through winter. Avoid mulching during summer heat — the decomposition process can generate enough heat to stress plants.
Should I use bulk or bagged mulch?
Use bags for projects under 2 cubic yards (about 27 bags of 2 cu ft). Above that, bulk delivery is cheaper — a cubic yard costs $30-50 bulk vs $65-100 in bags. Bags are easier to transport and store but generate significant plastic waste.
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