Garden Bed Dimensions

Length (ft)

Width (ft)

Depth (in)

Bag Size (cu ft per bag)

Mulch Needed

Bulk order

For beds > 1 cubic yard, ordering in bulk is typically more economical than bags.

How to Use

1
Measure the length and width of your garden bed or area in feet
2
Choose the desired mulch depth - 3 inches is recommended for a new bed to suppress weeds
3
Select your bag size if purchasing in bags, or use the cubic yards figure for bulk orders
4
For irregularly shaped beds, estimate the average length and width, or break the area into rectangles and add totals

Formula

Volume (cu ft) = Length (ft) × Width (ft) × Depth (in) ÷ 12

Cubic Yards = Volume (cu ft) ÷ 27

Depth in inches is divided by 12 to convert to feet, then multiplied by the area. The result in cubic feet is divided by 27 to get cubic yards, or by the bag size to get the number of bags.

Examples

Front garden bed: 20 × 4 ft, 3 inches deep

20 × 4 × (3/12) = 20 cu ft ÷ 27 = 0.74 cu yd | 10 bags (2 cu ft)

Result: 0.74 cu yd or 10 bags

Tree ring: 8 × 8 ft, 4 inches deep

8 × 8 × (4/12) = 21.3 cu ft ÷ 27 = 0.79 cu yd | 11 bags (2 cu ft)

Result: 0.79 cu yd or 11 bags

Large border: 50 × 5 ft, 3 inches deep

50 × 5 × (3/12) = 62.5 cu ft ÷ 27 = 2.31 cu yd | 32 bags (2 cu ft)

Result: 2.31 cu yd - order in bulk at this quantity

FAQ

2-4 inches is the general recommendation. 2 inches is fine for refreshing an existing mulched bed. 3-4 inches provides better weed suppression for new beds. Avoid piling mulch against plant stems or tree trunks - leave a gap of several inches.

Bulk mulch is generally more cost-effective for orders above 1-2 cubic yards. A cubic yard is 27 cubic feet, equivalent to 13-14 standard 2-cu-ft bags. For smaller jobs or limited delivery access, bagged mulch is more convenient.

Yes - the volume formula (length × width × depth) is the same for topsoil, compost, gravel, and sand. The only difference is that these materials are sold by weight or cubic yard, and their bulk density varies. The cubic yards result applies directly.

Pro Tip

Apply mulch in spring after the soil has warmed, or in fall before the first frost. Avoid piling mulch against plant stems (called "mulch volcanos") - this traps moisture and can cause root rot and pest issues.