Mulch Calculator

1. Choose how you know the area. Select "Length & width" if you measured the bed, "Known area" if you already have the square footage, or "Circle / tree ring" for round beds around trees. For irregular beds, measure the widest rectangle that fits and use a 10% buffer to cover the curves.
2. Enter bed dimensions. For rectangular beds, enter length and width. For circles, enter the outer radius. For tree rings, enter both the outer radius and the trunk clearance radius. The mulch calculator handles the ring math for you.
3. Set the mulch depth. Use 2 inches for a refresh layer over existing mulch. Use 3 inches for most landscape beds. Use 4 inches for heavy weed suppression or playground areas. The default is 3 inches.
4. Add extra beds (optional). If you have multiple beds of the same size, set the number of beds instead of running the calculator separately for each one. For beds of different sizes, calculate each size individually and add the results.
5. Choose a bag size or plan for bulk. Most home center bags hold 2 cubic feet. The mulch calculator shows both bag count and bulk cubic yards so you can compare prices. Bulk mulch runs $25 to $50 per cubic yard in 2026, while bagged mulch costs $3 to $6 per 2 cu ft bag. This works for bark mulch, hardwood mulch, cedar mulch, and rubber mulch. Rubber playground mulch bags are often 0.8 cu ft, so use the custom bag size option.
6. Add a buffer (recommended). A 10% buffer covers uneven soil, bed edges, and settling after rain. I once spread mulch on a sloped front bed and ran short along the downhill edge because the depth was thinner on the high side. A small buffer saves a second trip to the store.

Pro tip: Measure depth at the center and both ends of the bed, then average them. Mulch settles unevenly on sloped or freshly graded soil, and averaging prevents under-ordering. Don't pile mulch against tree trunks or plant stems. Keep a 3 to 4 inch gap around trunks to prevent rot and pest problems. Run this mulch calculator once per bed size if your beds differ in dimensions.

This mulch calculator converts your bed dimensions into ordering quantities using area, volume, and bag math.

Volume:

Cubic feet = Area (sq ft) × Depth (ft)

Cubic yards = Cubic feet / 27

Bags:

Bag count = Cubic feet / Bag size (cu ft), rounded up to the next whole bag

Circle or tree ring:

Area = π × (Outer radius² − Inner radius²)

For a full circle, the inner radius is zero, so the formula simplifies to π × radius².

With buffer:

Adjusted quantity = Base result × (1 + Buffer % / 100)

Variables:

• Area = bed surface in square feet (length × width, entered directly, or circle formula)
• Depth = mulch thickness in feet (divide inches by 12, so 3 inches = 0.25 ft)
• Bag size = volume per bag in cubic feet (2 cu ft is the most common retail size)
• Buffer = percentage added for edges, settling, and uneven ground
• Beds = number of same-size beds to multiply the area

Coverage reference by depth:

Example:

A 12 ft × 20 ft bed at 3 inches deep with 10% buffer.

• Area = 12 × 20 = 240 sq ft
• Depth in feet = 3 / 12 = 0.25 ft
• Cubic feet = 240 × 0.25 = 60 ft³
• With 10% buffer = 60 × 1.10 = 66 ft³
• Cubic yards = 66 / 27 = 2.44 yd³
• Bags (2 cu ft) = 66 / 2 = 33 bags

At 33 bags, bulk delivery is usually cheaper. Bulk mulch costs $25 to $50 per cubic yard in 2026. Cedar and black-dyed mulch run toward the higher end. A typical landscape supplier delivers 2 to 5 cubic yards per load, plus $50 to $150 for delivery depending on distance. Use this mulch calculator to compare bag cost versus bulk cost before ordering.

Bag comparison reference:

Assumptions:

• The bed area has uniform depth. For uneven ground, measure depth at several points and average them
• The calculator estimates volume, not placement. Keep mulch 3 to 4 inches away from tree trunks and plant stems to prevent moisture rot
• Existing mulch reduces the new depth needed. If the old layer is still 1 inch thick, subtract 1 inch from your target depth for a refresh
• For irregular or L-shaped beds, split into rectangles, calculate each, and add the results
• Playground mulch typically requires 6 to 12 inches of depth to meet ASTM F1292 safety standards. Adjust depth accordingly for play areas