Mulch Calculator
This free mulch calculator turns your bed dimensions and depth into cubic yards, bag count and a bulk-vs-bags cost comparison for mulch, topsoil or compost.
What this calculator does
This planner converts a bed's length, width and desired depth into cubic yards and bags of mulch, topsoil or compost, and compares the cost of buying bulk vs. bagged material.
How the math works
- Volume: area (length × width) × depth, converted from inches to feet, plus your waste allowance.
- Bags: volume in cubic feet ÷ the material's bag size, rounded up.
- Bulk vs. bags: compares the mid-range cost per cubic foot of bulk delivery against bagged material, and factors in typical bulk delivery minimums, to suggest which is more practical at your quantity.
Worked example
A 20 ft by 10 ft bed (200 sq ft) at 3 in of shredded hardwood mulch: 50 cu ft, plus 10% waste = 55 cu ft — about 2 cu yd, or 28 two-cubic-foot bags. Bagged runs roughly $112–$168; bulk delivered runs about $71–$112, making bulk the more economical choice at this quantity.
Frequently asked questions
How much mulch do I need?
Multiply length by width to get square feet, multiply by depth (in feet), then divide by 27 for cubic yards. A 20 ft by 10 ft bed at 3 in deep needs about 2 cubic yards, or roughly 28 two-cubic-foot bags.
How deep should mulch be?
2 to 3 inches is typical for most garden beds — enough to suppress weeds and retain moisture without smothering roots or promoting rot against stems and trunks.
Is it cheaper to buy mulch in bulk or in bags?
Bulk delivery is usually more economical per cubic yard once you're above most suppliers' delivery minimum (commonly around 1 cubic yard). Below that, bagged material is often more practical.
How often should I replace mulch?
Organic mulches typically break down and need topping off every 1 to 2 years, depending on climate and mulch type. A thin top-up layer is often enough.
What is the difference between mulch, topsoil and compost?
Mulch is a surface layer that suppresses weeds and retains moisture. Topsoil is a bulk fill/planting medium. Compost is a nutrient-rich amendment typically worked into the soil rather than left on the surface.
Limitations
This tool estimates material quantities and typical costs only. Bulk delivery minimums, access for delivery trucks and local pricing vary by supplier — confirm before ordering.
Put this calculator on your site
Run a blog or business site for DIYers, homeowners or contractors? You can embed the Mulch & Landscape Material Calculator as a free widget — responsive, no registration, and no ads or tracking added to your page.
Cite this calculator
Using this tool in a class, a paper or an article? Copy a ready-made reference: