Mulch Calculator
Calculates the cubic yards of mulch required to cover a garden bed to a specified depth. Ideal for homeowners and landscapers buying bulk mulch by the yard.
About this calculator
Mulch is sold in bulk by the cubic yard, so you need to convert your bed's area and desired depth into cubic yards before ordering. The depth is given in inches and must first be converted to feet by dividing by 12. The volume in cubic feet is then: Volume (cu ft) = area × (depth / 12). Because there are 27 cubic feet in one cubic yard, the final formula is: Cubic Yards = (area × (depth / 12)) / 27. Most garden beds benefit from 2–3 inches of mulch for weed suppression and moisture retention, while tree rings may need up to 4 inches. Knowing your exact cubic yardage prevents both expensive over-ordering and frustrating mid-project shortages.
How to use
Imagine you have a garden bed with a total area of 300 sq ft and you want to apply mulch 3 inches deep. Step 1 — Convert depth to feet: 3 / 12 = 0.25 ft. Step 2 — Calculate volume in cubic feet: 300 × 0.25 = 75 cu ft. Step 3 — Convert to cubic yards: 75 / 27 ≈ 2.78 cubic yards. You would order 3 cubic yards of bulk mulch to be safe. At a typical cost of $30–$50 per yard, that's roughly $90–$150 for the project.
Frequently asked questions
How deep should I apply mulch in my garden beds?
A depth of 2–3 inches is recommended for most flower and shrub beds — enough to suppress weeds and retain soil moisture without smothering plant roots. For pathways or heavy weed-prone areas, 4 inches can be used. Avoid piling mulch directly against tree trunks or plant stems, as this can cause rot and pest problems. Refresh existing mulch annually by adding just 1 inch on top of the settled layer.
How many cubic yards of mulch are in a typical bulk truckload?
A standard bulk delivery in the United States is commonly 10–15 cubic yards, though suppliers offer loads as small as 1–2 cubic yards for smaller projects. A single cubic yard of mulch weighs roughly 400–800 lbs depending on moisture content and material type. Knowing your calculated cubic yardage helps you choose between buying bagged mulch from a hardware store (which costs more per yard) or ordering bulk delivery, which becomes cost-effective above about 3 cubic yards.
What type of mulch is best for vegetable gardens versus flower beds?
For vegetable gardens, organic mulches like straw, shredded leaves, or untreated wood chips are preferred because they break down and enrich the soil. Avoid dyed or treated wood mulch near edible plants. For ornamental flower beds, shredded hardwood or bark nuggets are popular choices that decompose slowly and resist washing away. Pine straw is excellent for acid-loving plants like azaleas and blueberries. Your mulch type does not change the volume calculation, but density varies, so confirm coverage rates with your supplier.