Buying mulch sounds simple until you’re standing at the landscape supply yard and someone asks how many yards you want. Buy too little and you’re making a second trip. Buy too much and there’s a pile in the driveway for three weeks.
The formula is straightforward, but most homeowners and even newer landscapers skip a step or two and end up with the wrong amount. This guide walks through how to calculate exactly how much mulch you need, what depth to use for different applications, the bag vs. bulk decision, and two worked examples with full math.
If you want the math handled for you, plug your numbers into our free mulch calculator.
Quick Answer: How Much Mulch Do I Need?
Use this formula: (Length in feet x Width in feet x Depth in inches) / 324 = Cubic Yards
The number 324 handles the unit conversion for you. It accounts for the 27 cubic feet in a cubic yard and the 12-inch-per-foot depth conversion. One formula, one division, done.
Rule of thumb coverage at 3 inches (the standard depth):
- 1 cubic yard covers about 108 square feet
- 2 cubic yards cover about 216 square feet
- 1 bag (2 cu ft) covers about 8 square feet at 3 inches
If you just need a ballpark, one cubic yard per 100 square feet of bed area at standard depth is a reliable starting point. For a precise number, keep reading or use the mulch calculator.
The Full Mulch Formula
Cubic yards = (Length ft x Width ft x Depth in) / 324
Alternatively: (Length ft x Width ft x Depth ft) / 27
Why 324? There are 27 cubic feet in a cubic yard, and 12 inches in a foot. 27 x 12 = 324. That constant handles both conversions in one step.
If you have multiple beds, calculate each one separately and add the totals. Eyeballing a combined average is how you end up short on one bed and with leftover material piled next to another.
Depth Guidelines by Mulch Type
Depth is the variable most people guess at, and it varies by both application and mulch type. Here is the full breakdown.
| Mulch Type | Recommended Depth | Notes |
|---|---|---|
| Fine hardwood / dyed mulch | 2 inches | Dense material, compacts more than coarser types |
| Standard hardwood | 3 inches | Most common residential application |
| Shredded cedar / cypress | 3 inches | Slower to break down, good for 2-3 year longevity |
| Pine bark nuggets | 3-4 inches | Larger pieces need more depth for weed suppression |
| Playground wood chips | 4-6 inches | ASTM fall height safety requirements apply |
| Straw mulch (vegetable gardens) | 2-3 inches | Thicker causes nitrogen issues as it decomposes |
| Rubber mulch | 3 inches | Does not break down, does not need seasonal refresh |
Depth by Application
2 inches: Refreshing a bed that still has a solid base layer. Not effective for weed suppression on bare soil.
3 inches: The standard for most residential beds, around shrubs, perennials, and trees. Thick enough to suppress weeds and retain moisture without blocking air and water from roots.
4 inches: Slopes, heavy weed pressure, and paths. Do not exceed 4 inches in regular landscape beds.
4-6 inches: Playgrounds only, per ASTM fall-height safety requirements.
At every depth: Keep mulch 3-4 inches away from tree trunks and shrub bases. Piling against bark traps moisture and causes rot.
Coverage Per Cubic Yard by Depth
| Depth | Coverage per Cubic Yard |
|---|---|
| 1 inch | 324 sq ft |
| 2 inches | 162 sq ft |
| 3 inches | 108 sq ft |
| 4 inches | 81 sq ft |
| 6 inches | 54 sq ft |
Worked Example 1: Single Flower Bed
A homeowner wants to mulch a flower bed along the front of their house. The bed is 24 feet long and 4 feet wide. They have existing mulch that has broken down to about half an inch, and they want to top it off to a fresh 3 inches total.
Step 1: Calculate the area
- 24 ft x 4 ft = 96 square feet
Step 2: Determine effective depth needed
- Existing depth: 0.5 inches
- Target depth: 3 inches
- New material needed: 3 - 0.5 = 2.5 inches
Step 3: Apply the formula
- (24 x 4 x 2.5) / 324
- 240 / 324 = 0.74 cubic yards
Step 4: Add 10% overage
- 0.74 x 1.10 = 0.81 cubic yards
Order: 1 cubic yard. Rounding up to the nearest half or full yard is standard practice. The small excess fills any low spots and accounts for settling.
In bags: 1 cubic yard = about 13.5 standard 2-cubic-foot bags. Buying 14 bags makes sense when you don’t want a bulk delivery for under a yard.
Worked Example 2: Large Yard Perimeter Beds
A contractor is mulching the full landscaping package around a new house. The property has four distinct bed sections along the perimeter:
- Front foundation bed: 42 ft x 5 ft
- Left side yard bed: 18 ft x 3 ft
- Right side yard bed: 22 ft x 3 ft
- Back patio bed along fence: 30 ft x 4 ft
All beds are bare soil, new installation. Client wants standard hardwood mulch at 3 inches.
Calculate each bed separately:
| Bed | Dimensions | Area (sq ft) | Formula | Cubic Yards |
|---|---|---|---|---|
| Front foundation | 42 x 5 | 210 | (42 x 5 x 3) / 324 | 1.94 |
| Left side yard | 18 x 3 | 54 | (18 x 3 x 3) / 324 | 0.50 |
| Right side yard | 22 x 3 | 66 | (22 x 3 x 3) / 324 | 0.61 |
| Back patio bed | 30 x 4 | 120 | (30 x 4 x 3) / 324 | 1.11 |
| Total | 450 sq ft | 4.16 yards |
Add 10% overage: 4.16 x 1.10 = 4.58 yards
Order: 5 cubic yards. At this volume, bulk delivery is the right call. Buying bags would cost $200-300 more than a bulk order with delivery. The truck can dump the full load in one spot, and the installer wheelbarrows to each bed.
Bulk delivery note: Confirm the truck can access the property before ordering. Narrow driveways, low-hanging trees, or soft soil after rain can block a standard landscape dump truck. Ask the supplier about their truck size when you call.
For a full estimate that includes mulch material, delivery, edging, and installation labor, use the landscaping cost calculator.
Bag vs. Bulk: The Real Cost Comparison
Bulk wins once you are past 3 cubic yards. For a breakdown of bulk prices by mulch type and seasonal timing, see mulch cost per yard.
Bagged Mulch
- Standard bag: 2 cubic feet | Bags per cubic yard: about 13.5
- Retail price: $3.50 to $6.00 per bag | Cost per cubic yard: $47 to $81
Best for touch-up jobs under 2 yards or when bulk delivery is not practical. You pay a premium for packaging and convenience.
Bulk Mulch
- Price per cubic yard: $25 to $50 (hardwood/cedar), $75 to $120 (rubber)
- Delivery fee: $50 to $150
Best for any job over 3 cubic yards. You need to be home for delivery and move the pile to the beds yourself.
Cost Comparison Table
| Volume | Bagged Cost (at $4.50/bag) | Bulk Cost (at $38/yd + $75 delivery) | Savings with Bulk |
|---|---|---|---|
| 2 cubic yards | $121 | $151 | Bags win here |
| 3 cubic yards | $182 | $189 | About even |
| 5 cubic yards | $304 | $265 | $39 savings |
| 10 cubic yards | $608 | $455 | $153 savings |
| 20 cubic yards | $1,215 | $835 | $380 savings |
The crossover point is around 3 yards. Below that, bags are competitive when you factor in delivery fees. Above 3 yards, bulk wins every time.
Try EstimationPro free to build full landscaping estimates with material quantities, delivery costs, and labor in one place.
Mulch Type Comparison
Not all mulch performs the same, and the type affects depth requirements, longevity, cost, and how beds look year to year.
| Mulch Type | Cost per Yard (Bulk) | Longevity | Best Use |
|---|---|---|---|
| Shredded hardwood | $25-$40 | 1-2 years | General landscape beds, most versatile |
| Dyed hardwood (brown/black/red) | $30-$45 | 1-2 years | Curb appeal, clean appearance longer |
| Cedar / cypress | $35-$55 | 2-3 years | Low-maintenance, natural insect repellent properties |
| Pine bark nuggets | $30-$50 | 2-3 years | Around acid-loving plants (azaleas, rhododendrons) |
| Straw | $5-$10 per bale | 1 season | Vegetable gardens, erosion control on bare slopes |
| Rubber mulch | $75-$120 | 10+ years | Playgrounds, areas where decomposition is not wanted |
Hardwood is the most widely available and affordable option. Cedar and cypress last 2-3 years instead of 1-2, which often justifies the price difference. Pine bark works well around acid-loving plants. Rubber mulch does not decompose, contributes nothing to soil health, and is difficult to remove later.
Measuring Irregular Landscape Beds
Real beds are not always clean rectangles.
Curved beds: Break them into approximate rectangles. Measure each section, calculate separately, and add the totals. Within 10% is accurate enough for ordering.
Circular beds around trees: Area = 3.14 x radius x radius. A 4-foot radius ring: 3.14 x 16 = 50.3 sq ft. Keep the inner edge 3-4 inches away from the trunk and subtract that gap from your area.
L-shaped or complex beds: Split into rectangles, calculate each, add them up. For help with the geometry, a square footage calculator handles the area math before you apply the mulch formula.
The 10% rule: Always add 10% to your calculated volume. Beds are not perfectly flat, material settles, and there is loss during transport. Multiply your calculated volume by 1.10, round up to the nearest half yard, and place the order.
When to Refresh Mulch
Hardwood mulch: Every 1-2 years. It breaks down into the soil, improving the bed over time.
Cedar or cypress: Every 2-3 years. Worth the higher upfront cost for clients who want less frequent maintenance.
Pine bark: Every 1-2 years for smaller nuggets, 2-3 years for larger sizes.
Rubber mulch: Does not break down. Top off only if displaced.
Best timing: Spring is the primary window - weed seeds have not germinated and fresh mulch sets up suppression for the growing season. Fall is the second option for insulating roots going into winter.
On removing old mulch: Do not remove it unless it is matted, moldy, or the total depth is already at 4-5 inches. Rake it loose and top it off.
Pro Tips for Contractors
Add 10% to every order. Beds are not perfectly flat, material is lost in transport, and clients always want a bit extra. Build the overage in before you call.
Price installation at $45-$75 per cubic yard installed for residential work. That covers material, delivery, spreading, and cleanup. Adjust up for limited access, steep slopes, or when edging is included.
Confirm delivery access before ordering bulk. A landscape truck that cannot reach the dump spot turns a simple job into a manual hauling problem.
FAQ
How many bags of mulch equal a cubic yard?
Standard 2-cubic-foot bags: about 13.5 bags per cubic yard. If you are using 3-cubic-foot bags, you need about 9 per yard.
How much area does 1 yard of mulch cover?
At 3 inches (the standard depth), 1 cubic yard covers about 108 square feet. At 2 inches it covers 162 square feet. At 4 inches it covers 81 square feet.
Is bulk mulch really cheaper than bagged?
For orders over 3 cubic yards, yes. Bagged mulch costs the equivalent of $47-$81 per cubic yard. Bulk costs $25-$50 per yard before delivery. The savings grow significantly with volume.
How do I calculate mulch for curved or irregular beds?
Break the area into approximate rectangles. Measure each section, calculate cubic yards for each, and add the totals. Being within 10% is accurate enough.
Should I remove old mulch before adding new?
Usually no. Rake it loose and top it off. Only remove old mulch if it is matted, moldy, or already piled so deep that adding more would push total depth above 5-6 inches.
How deep should mulch be around trees?
Three inches is standard, with a 3-4 inch gap between the mulch and the trunk. Never pile mulch against the bark (“volcano mulching”). It traps moisture and leads to rot.
What is the difference between cubic yards and cubic feet for mulch?
One cubic yard equals 27 cubic feet. Bulk mulch is sold by the yard. Bagged mulch lists cubic feet per bag. To convert: bags x bag size / 27 = cubic yards.
Want to build complete landscaping estimates in minutes? Try EstimationPro free to turn project details into professional, line-item estimates with accurate material quantities, delivery costs, and labor.
Mulch prices vary by region, supplier, and season. The ranges in this guide reflect typical U.S. residential market pricing as of early 2026. Coastal and urban markets often run 15-25% above these figures. Midwest and rural markets may run 10-15% below. Always get a local quote before finalizing your material budget.
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