Mulch Calculator: Calculate Mulch for Garden Beds and Landscaping
Use our free mulch calculator to find out exactly how much mulch you need for garden beds, tree rings, playgrounds, and landscaping projects. Designed for landscapers, gardeners, and homeowners, this tool converts your bed dimensions and desired depth into cubic yards, square footage of coverage, and the number of bags to buy.
How to use this calculator.
- Enter bed dimensions. Input the length and width of the garden bed, tree ring, or landscaped area in feet.
- Set the mulch depth. Enter your desired depth in inches. Most beds call for 2-4 inches.
- Choose your bag size. The default is 2 cu ft, the most common bagged mulch size at home improvement stores.
- Review your results. The calculator displays volume (cubic yards), coverage area, and the number of bags needed instantly.
- Print or save. Use your browser's print function for a supply list before heading to the store or scheduling a bulk delivery.
How do you calculate mulch volume and coverage?
To calculate mulch volume, multiply the bed area (length × width) by the depth (converted from inches to feet), then convert to cubic yards. Coverage and bag count are derived from that volume.
Volume (cu yd) = Length (ft) × Width (ft) × Depth (in) ÷ 12 ÷ 27
Coverage (sq ft) = Volume (cu yd) × 324 ÷ Depth (in)
Bags Needed = Volume (cu yd) × 27 ÷ Bag Size (cu ft)
Where:
- Length and width: The dimensions of the bed or area to be mulched, in feet.
- Depth: The thickness of the mulch layer, in inches.
- Bag size: The volume of a single mulch bag, in cubic feet. Standard bags are 2 cu ft; some suppliers sell 3 cu ft bags.
- Coverage constant (324): One cubic yard of mulch covers 324 sq ft spread 1 inch deep, or 108 sq ft at 3 inches deep.
Example calculation.
Let's calculate mulch for a flower bed along a foundation.
Scenario: A garden bed measuring 25 ft long and 15 ft wide, mulched 3 inches deep, using standard 2 cu ft bags.
- Calculate the area: 25 ft × 15 ft = 375 sq ft
- Convert depth to feet: 3 inches ÷ 12 = 0.25 ft
- Calculate volume in cubic feet: 375 sq ft × 0.25 ft = 93.75 cu ft
- Convert to cubic yards: 93.75 cu ft ÷ 27 = 3.47 cu yd
- Calculate bags needed: 3.47 cu yd × 27 ÷ 2 cu ft = 46.9 bags
Result: You need approximately 3.47 cubic yards of mulch, or 47 bags at 2 cu ft each, to cover this 375 sq ft bed at 3 inches deep.
Tips from the field.
- Order 10-15% extra. Mulch settles and compacts after placement and watering, so bulk deliveries measured by loose volume run short once spread and packed down.
- Stick to 2-3 inches for flower beds. Thicker layers (beyond 4 inches) can suffocate roots, trap excess moisture, and encourage fungal growth.
- Avoid mulch volcanoes. Keep mulch 2-3 inches away from tree trunks and plant stems: piling mulch against bark traps moisture and invites rot and pests.
- Bulk beats bagged for large jobs. Bulk mulch by the cubic yard is typically 30-50% cheaper than the equivalent bagged volume once you're covering more than a few hundred square feet.
- Refresh instead of replace. Rake and fluff existing mulch each spring and top-dress with 1-2 inches of fresh material rather than removing and replacing the full depth every year.
Disclaimer: This calculator provides estimates for planning purposes only. Actual mulch requirements vary based on bed shape, settling, and moisture. PavementCalculator.com assumes no liability for material overages or shortages.
Cost, price, and density figures on this page reflect approximate U.S. averages as of August 2026 and vary by region, supplier, and material availability.
Frequently asked questions.
How much mulch do I need?
Measure your garden bed length × width in feet, then multiply by desired depth in feet (inches ÷ 12), and divide by 27 for cubic yards. For a 25 ft × 15 ft bed at 3 inches deep: 25 × 15 × 0.25 ÷ 27 = 3.47 cubic yards. One cubic yard covers 324 sq ft at 1 inch deep. Use our calculator above for instant results.
How many bags of mulch equal a cubic yard?
One cubic yard equals 13.5 bags of standard 2-cubic-foot mulch, or 9 bags of 3-cubic-foot mulch. Bulk mulch by the yard ($25-$50/yd³) is significantly cheaper than bagged mulch ($2-$5 per 2-cu-ft bag, equivalent to $27-$67/yd³). For large projects, bulk delivery saves 30-50%.
How deep should mulch be applied?
Apply 2-3 inches of mulch for flower beds and around trees and shrubs. Apply 3-4 inches for weed suppression in new beds. Never exceed 4 inches: too much mulch can suffocate plant roots, prevent water penetration, and encourage fungal growth. Keep mulch 2-3 inches away from tree trunks and plant stems.
How much does mulch cost per yard?
Bulk mulch costs $25-$50 per cubic yard depending on type. Shredded hardwood costs $30-$40/yd³, dyed mulch (red, black, brown) costs $35-$50/yd³, pine bark costs $30-$45/yd³, and cedar mulch costs $35-$55/yd³. Delivery fees typically add $40-$75. Most suppliers require a minimum of 3-5 yards for delivery.
When should I replace or refresh mulch?
Refresh mulch annually in spring: rake and fluff existing mulch, then add 1-2 inches of fresh mulch on top. Completely replace mulch every 2-3 years as it decomposes into the soil. Organic mulches (wood chips, bark) break down faster than inorganic mulches (stone, rubber). Remove old mulch if fungal growth or compacted layers develop.
How do I calculate mulch for a circle (around a tree)?
Calculate the area of the circle: π × radius² (radius in feet). Subtract the tree trunk area if large. Multiply by desired depth in feet, then divide by 27 for cubic yards. For a 6-foot diameter circle at 3 inches deep: π × 3² × 0.25 ÷ 27 = 0.26 cubic yards (about 4 bags of 2-cu-ft mulch).