Mulch Calculator

How to Calculate Mulch

Our mulch calculator estimates how many cubic yards or bags of mulch you need for your garden beds. Multiply the bed length by the width to get square footage, then multiply by the depth in feet to get cubic feet. Divide by 27 to convert to cubic yards, and add about 5% for settling and uneven ground.

Choosing a Mulch Type

• Hardwood Mulch: Affordable and widely available - breaks down to enrich soil
• Cedar Mulch: Naturally insect-resistant with a longer-lasting color and aroma
• Rubber Mulch: Long-lasting and low maintenance - best for playgrounds and paths
• Dyed Mulch: Black, brown, or red color that holds up longer than natural mulch

Mulch Depth Guidelines

Apply 2 inches of mulch in flower beds and around perennials, and 3-4 inches around trees and shrubs. A 3-inch depth is the sweet spot for most beds - deep enough to suppress weeds and retain moisture without smothering plant roots. Avoid piling mulch against trunks and stems, which traps moisture and invites rot.

Mulch Calculator Formula

The calculator works in feet and inches (metric entries are converted first) and uses these steps and constants:

1. Bed area: length × width, in square feet
2. Cubic feet: bed area × (depth in inches ÷ 12)
3. Cubic yards: cubic feet ÷ 27, then × 1.05 for a 5% settling allowance
4. Bags: cubic feet × 1.05 ÷ bag size (2 cu ft or 3 cu ft), rounded up to whole bags
5. Coverage per bag: bag size ÷ (depth ÷ 12), in square feet
6. Material cost: cubic yards × $30 to $60 per cubic yard, a 2026 national bulk range, before delivery

In one line: cubic yards = length × width × (depth ÷ 12) ÷ 27 × 1.05. One cubic yard holds 13.5 bags of 2 cu ft or 9 bags of 3 cu ft.

Worked Example: 10 x 20 ft Bed at 3 Inches

A 10 ft by 20 ft garden bed with a 3 inch layer of mulch:

• Bed area: 10 × 20 = 200 sq ft
• Volume: 200 × (3 ÷ 12) = 50 cu ft
• Cubic yards: 50 ÷ 27 = 1.85, plus 5% = 1.94 cu yd
• 2 cu ft bags: 50 cu ft plus 5% = 52.5 cu ft, ÷ 2 = 26.25, rounded up to 27 bags (each covers 8 sq ft at 3 inches)
• 3 cu ft bags: 52.5 ÷ 3 = 17.5, rounded up to 18 bags (each covers 12 sq ft at 3 inches)
• Material cost: 1.94 cu yd at $30 to $60 per cubic yard, which the calculator rounds to $60 to $120

These are the figures the calculator shows for the same bed. Whether bags or bulk is cheaper depends on local prices and the delivery fee, so check how much a yard of mulch costs by type, per bag and in bulk before you buy. Mulching beds as part of a bigger project? The landscaping calculator also estimates topsoil, sand and gravel.

Mulch Coverage per Cubic Yard and per Bag

Mulch is sold by volume, so coverage is simple geometry: the volume spread at your depth. A cubic yard is 27 cubic feet, the same as 13.5 bags of 2 cu ft or 9 bags of 3 cu ft.

Areas are exact volumes before the 5% settling allowance the calculator adds, rounded to the nearest square foot. Fresh mulch settles after watering and raking, which is what the allowance covers.