How this calculator works
Bed area × depth gives cubic feet; divide by 27 for cubic yards or by the bag size for bags. One cubic yard spread 1 in deep covers 324 sq ft, so it covers 324 ÷ depth square feet.
For several beds, list each one on its own line: rectangles as length × width, circles by diameter and triangles by base and height. Add “@ 2” to give a bed its own depth in inches. Enter a bag price and a bulk price per yard (plus delivery) to see which way of buying costs less.
Assumptions and tips
- Bulk mulch is often cheaper than bags once you need more than a couple of yards, but delivery fees can wipe out the saving on small orders.
- Circle area = π × (diameter ÷ 2)²; triangle area = base × height ÷ 2.
Worked example
Using the default values in the calculator above:
| Input | Value |
|---|---|
| Beds | One size (length × width) |
| Length | 20 ft |
| Width | 10 ft |
| Number of beds this size | 1 |
| Mulch depth | 3 in |
| Bag size | 2 cu ft |
| Price per bag (optional) | $0 |
| Bulk price (optional) | 0 $/yd³ |
| Bulk delivery fee | $0 |
| Result | Value |
|---|---|
| Bulk mulch | 1.85 cubic yards |
| 2 cu ft bags | 25 bags |
| Volume | 50 cubic feet |
| Area covered | 200 sq ft |
| One yard covers at this depth | 108 sq ft |
Step by step:
- Area = 20 × 10 × 1 = 200 sq ft
- Volume = 200 × 3/12 = 50 cu ft = 1.852 yd³
- Bags = 50 ÷ 2 → 25
Mulch for common bed sizes
3 in deep; bags are 2 cu ft.
| Bed area | Bulk mulch | 2 cu ft bags |
|---|---|---|
| 50 sq ft | 0.46 cubic yards | 7 bags |
| 100 sq ft | 0.93 cubic yards | 13 bags |
| 200 sq ft | 1.85 cubic yards | 25 bags |
| 300 sq ft | 2.78 cubic yards | 38 bags |
| 500 sq ft | 4.63 cubic yards | 63 bags |
| 1000 sq ft | 9.26 cubic yards | 125 bags |
Common mistakes to avoid
- Piling mulch against trunks (“mulch volcanoes”).
- Laying fresh mulch 3 in deep on top of last year’s 3 in.
Frequently asked questions
How many bags of mulch are in a yard?
13.5 two-cubic-foot bags make one cubic yard.
Is bagged or bulk mulch cheaper?
Per yard, bulk is usually much cheaper — but once you add a delivery fee, bags often win for orders under about 2–3 yards. Enter your local prices above to compare.
How much area does a yard of mulch cover?
About 108 sq ft at 3 in deep, or 162 sq ft at 2 in.