Mulch efficiently.
Cubic yards of mulch for any garden bed. Shows bag count if you're buying in bags, and bulk yardage if you're ordering by the truck.
How we calculated this
The calculator multiplies bed area (length × width) by depth to compute total volume. Depth is entered in inches or centimeters and converted to feet or meters before the multiplication so everything is in consistent units.
Imperial results are converted from cubic feet to cubic yards by dividing by 27. Cubic yards is the standard bulk sale unit at landscape suppliers. Metric results stay in cubic meters directly.
For bag calculations, the standard bag is 2 cubic feet of mulch (which is 0.074 cubic yards or about 0.057 cubic meters). Bags round up to the nearest whole bag because you can't buy a partial bag.
The right depth depends on your goals: 2 inches keeps weeds down in established beds; 3 inches is standard for new beds or areas needing moisture retention; 4 inches is for heavily weeded areas or around shrubs. Going deeper than 4 inches can suffocate plant roots.
Volcano mulching is killing your trees
Before getting into the math, here is the single most important thing about mulch that most people get wrong. Every spring, landscaping crews across the country pile mulch into tall cones against tree trunks. It looks tidy. It is slowly killing the tree. The practice is called volcano mulching, and arborists have been fighting it for decades with limited success because it looks intentional.
What happens: mulch piled against bark holds moisture against the wood. The bark, which evolved to shed water, stays perpetually damp. Fungal colonies establish. The cambium layer (the living tissue just under the bark) rots. Secondary roots grow into the mulch cone instead of spreading outward. Within 3 to 5 years, a mature tree that survived decades of weather can decline and die from the base up. The fix costs nothing: keep a 3 to 6 inch gap between mulch and any trunk or stem. The mulch ring should look like a donut, not a volcano.
How we calculated these numbers▾
Coverage formula: area (ft²) × depth (in) ÷ 324 = cubic yards. The 324 constant is 27 cubic feet per yard × 12 inches per foot. Bulk pricing reflects 2026 landscape supply yard rates across the Mid-Atlantic and Midwest. Bag pricing from Home Depot and Lowe's 2 cu ft bags. Mulch characteristics from Clemson Cooperative Extension HGIC 1604 and Penn State Extension mulching guidelines.
How depth changes everything
The formula is simple: area times depth divided by 324 gives you cubic yards. But the depth choice is where most people waste money, either overspending on mulch they do not need or underspending on mulch that will not suppress weeds.
New beds need 3 inches for effective weed suppression. That is the depth at which sunlight cannot reach the soil surface, preventing most annual weed seeds from germinating. Thinner than 2 inches and weeds push through within weeks. Thicker than 4 inches and the mulch itself becomes a problem: it mats down, repels rainfall instead of absorbing it, and can suffocate shallow root systems.
Annual top-ups on existing beds need only 1 to 2 inches. Organic mulch decomposes about an inch per year, so adding 1.5 inches each spring maintains the target depth without building up excess. If your existing mulch is still 2 inches thick, add 1 inch. If it has decomposed to a thin film, add 2 inches. Do not pile fresh mulch over 3 inches of existing mulch. The total depth, old plus new, should stay at 3 inches.
Bulk delivery vs bags: the $90 question
Composite illustration based on typical project dimensions, regional contractor pricing, and 2026 material costs. Not a specific real project.
The crossover point is about 2 cubic yards. Below that, bags are practical because bulk suppliers charge $40 to $75 for delivery on small orders, which erases the per-yard savings. Above 2 yards, bulk wins on cost and saves hours of loading, driving, and unloading 27+ bags per yard. One cubic yard weighs 400 to 800 pounds depending on moisture content. That is a lot of bags to carry from your car to the back yard.
Order bulk mulch by calling a local landscape supply yard, not a big-box store. Supply yards charge $25 to $45 per yard for hardwood bark. Home Depot and Lowe's delivery services charge $50 to $80 per yard for the same product because they are reselling from the same yards with a markup. Search "landscape supply near me" and call for pricing. Most deliver within 24 to 48 hours.
Picking your mulch type
Organic mulch | Inorganic (rock/rubber) | |
|---|---|---|
| Cost per year | $30–55/yd³ annually | $50–120/yd³ once |
| Soil benefit | Adds nutrients as it decomposes | None |
| Weed control | Good for 1 season | Good with fabric underneath |
| Best for | Garden beds, trees, shrubs | Foundation plantings, xeriscape |
| Common mistake | Piling too deep (>4") | Skipping weed barrier underneath |
Organic mulch is cheaper per application but needs annual refresh. Rock costs more up front but is permanent. Use landscape fabric under rock only, not under organic mulch.
Dyed mulch (red, black, brown) is worth addressing because it is everywhere. The dye itself is either iron oxide (safe) or carbon-based (safe). The concern is not the dye. It is the wood source. Dyed mulch is often made from recycled pallets, construction debris, and demolition wood. Some of that wood was treated with CCA (chromated copper arsenate), which leaches arsenic into soil. If you use dyed mulch, buy from a supplier that certifies their wood source. If the price seems too low, the wood source is probably questionable.
When to mulch
Timing matters more than most people realize. Mulching too early in spring (before soil warms) keeps the ground cold and delays perennial emergence. Mulching in midsummer works but the soil dries faster in heat, so water thoroughly before laying mulch. Fall mulching protects root systems through winter and gives the mulch time to begin decomposing before the next growing season.
For lawn projects, pair mulching with the topsoil calculator for garden bed prep or the sod calculator for new lawn areas adjacent to your beds. If you are building raised beds and need to calculate soil volume, the gravel calculator uses the same cubic yard formula and handles rectangular and irregular shapes.
How much does mulch cost for your yard?
Bags (DIY) | Bulk (DIY) | Bulk (installed) | |
|---|---|---|---|
| 500 sq ft at 3" | $200–280 (38 bags) | $120–165 (4.6 yd³) | $300–420 |
| 1,000 sq ft at 3" | $400–560 (76 bags) | $230–330 (9.3 yd³) | $575–840 |
| 2,000 sq ft at 2" | $550–770 (105 bags) | $310–440 (12.3 yd³) | $740–1,100 |
Professional mulch installation runs about $65-90 per cubic yard including material and labor. DIY cuts that to $35-55 per yard (bulk) but takes a full day for anything over 5 yards.
A typical suburban property with 500 to 800 sq ft of garden beds needs 4 to 7 cubic yards of mulch per year. At bulk prices, that is $120 to $300 in materials. The labor is the bigger cost: spreading 5 yards of mulch takes one person 4 to 6 hours with a wheelbarrow and rake. Two people cut it to 2 to 3 hours. This is why most landscape companies charge $65 to $90 per installed yard. You are paying for the hauling and spreading, not the mulch itself.
Sources
- University of Maryland Extension — Mulch Basics — Academic reference for proper mulch depth and application
- Sunset Magazine — Mulch Guide — Practical coverage and depth recommendations
Frequently asked
How much mulch do I need?
Depends on bed size and depth. A 20 × 4 ft bed at 3 inches deep needs about 0.75 cubic yards (about 10 bags). Use the calculator above for exact numbers. Most residential beds need between 0.5 and 3 cubic yards.
How deep should I apply mulch?
2-3 inches is standard for most garden beds. Go deeper (3-4 inches) for new beds, weedy areas, or around shrubs. Don't exceed 4 inches — too much mulch smothers plant roots and can cause rot. For refreshing existing mulch, 1 inch is often enough.
Is bulk mulch cheaper than bagged?
Usually significantly cheaper per cubic yard. Bagged mulch runs $3-6 per 2 cu ft bag; bulk mulch from a landscape supplier is typically $25-40 per cubic yard. Bulk is cheaper if you need more than about 10 bags (roughly 0.75 yards). Below that, bags are more practical because of delivery minimums.
How many bags of mulch are in a cubic yard?
A cubic yard equals about 13.5 bags of 2 cu ft mulch. So for a yard of mulch you'd need 14 bags (rounding up). Bags are easy to carry home; bulk requires a truck or delivery but is much cheaper per yard.
What's the difference between a cubic yard and a regular yard?
A regular yard is a linear measurement (3 feet). A cubic yard is a volume (3 ft × 3 ft × 3 ft = 27 cubic feet). Mulch is always sold by the cubic yard. When a supplier says 'a yard of mulch,' they mean one cubic yard.
When is the best time to mulch?
Early spring is ideal — after the soil warms but before summer heat. Mulch applied in early spring suppresses weeds before they emerge and conserves moisture through summer. Avoid mulching over cold, wet soil in winter (can promote rot) or over dry soil in peak summer (water first).
Does the calculator work for gravel or stone?
The volume math is identical for any bulk material — gravel, stone, sand, topsoil, compost. But bag sizes differ: stone bags are typically 0.5 cu ft, gravel is often sold by weight (tons). For gravel and stone, use the dedicated gravel calculator.
How much area does 1 cubic yard of mulch cover?
At 3 inches deep: about 108 sq ft. At 2 inches: 162 sq ft. At 4 inches: 81 sq ft. The rule of thumb: one cubic yard covers 100 square feet at 3 inches deep.
Was this calculator helpful?