A yard of mulch is 27 cubic feet, but how deep it spreads depends on the area you're covering
When you order a "yard" of mulch, you're ordering 27 cubic feet — that's a standard measurement in landscaping. But that cubic footage doesn't tell you how many square feet it will cover, because depth matters. The same 27 cubic feet will cover 108 square feet at 3 inches deep, 54 square feet at 6 inches deep, or 36 square feet at 9 inches deep. Most landscapers recommend 2 to 4 inches of mulch for flower beds and around trees, so a single yard typically covers somewhere between 81 and 162 square feet depending on how thick you spread it.
The confusion happens because "yard" is a volume measurement (how much stuff you have), not a coverage measurement (how far it goes). A landscaping supplier will sell you mulch by the cubic yard. Your garden beds need a certain depth. You have to do the math between them, or ask the supplier to help you figure out how many yards to order for your specific project.
Key Takeaways
- One cubic yard of mulch equals 27 cubic feet, the standard unit landscapers use when selling mulch.
- The same yard of mulch covers different areas depending on depth: 108 square feet at 3 inches, 54 square feet at 6 inches, or 36 square feet at 9 inches.
- Most mulch beds need 2 to 4 inches of depth for weed suppression and moisture retention, so calculate your square footage and desired depth before ordering.
- You can use an online mulch calculator or call your supplier with your square footage and preferred depth, and they can tell you how many yards to order.
Why mulch depth matters more than total volume
Mulch does two jobs: it blocks sunlight from reaching weed seeds, and it holds moisture in the soil. Neither job works well if the layer is too thin. At 1 inch deep, mulch barely suppresses weeds and dries out quickly. At 2 inches, you get decent weed control and some moisture benefit. At 3 to 4 inches, you get strong weed suppression and noticeably better moisture retention — this is the sweet spot for most flower beds and around shrubs.
Going deeper than 4 inches is usually wasteful and can actually harm plants. Mulch piled against tree trunks or plant stems traps moisture and can cause rot. Mulch deeper than 4 inches also stays wet longer in the center, which can encourage fungal growth and attract pests. So when you're calculating how many yards to order, start by deciding on your target depth — usually 3 inches — then work backward to the square footage your yard will cover.
How to calculate cubic feet from your garden measurements
The math is straightforward once you have three numbers: the length of your bed in feet, the width in feet, and your desired depth in inches. Multiply length times width to get square feet. Then multiply that by your depth in inches and divide by 12 (since there are 12 inches in a foot). That gives you cubic feet. Divide cubic feet by 27 to get cubic yards.
Example: a flower bed that is 10 feet long, 4 feet wide, and you want 3 inches deep. Length × width = 40 square feet. 40 × 3 inches ÷ 12 = 10 cubic feet. 10 ÷ 27 = 0.37 cubic yards, so you'd order 1 yard (suppliers sell in whole yards). For an irregularly shaped bed, break it into rectangles, calculate each one, and add them together.
Most landscaping suppliers have online calculators on their websites where you enter square footage and depth, and the calculator tells you how many yards to order. If you're not comfortable with the math, take a photo of your beds, note the approximate dimensions, and call the supplier — they do this calculation dozens of times a day and can give you an answer in minutes.
The difference between mulch types and how it affects coverage
Different mulch materials have different densities, which can slightly affect how much area one cubic yard covers. Hardwood mulch (made from shredded bark and wood) is denser and heavier than softwood mulch or pine bark. Shredded hardwood also breaks down more slowly, so it lasts longer in the bed before you need to top it off. Cypress and cedar mulches are lighter and more aromatic but cost more and break down faster.
For coverage purposes, the density difference is small enough that you can ignore it in your calculations. A cubic yard of hardwood mulch and a cubic yard of pine bark will cover roughly the same square footage at the same depth. The real difference is in longevity and cost. Hardwood mulch typically lasts 2 to 3 years before it breaks down enough that you need to add more. Pine bark lasts about 1 to 2 years. Cedar and cypress last longer but cost significantly more per yard.
Common mistakes when ordering mulch
The most common mistake is underestimating how much area you're covering. A flower bed that looks small often turns out to be 50 or 60 square feet once you measure it. Another mistake is ordering too little depth — 1 inch of mulch looks like a lot when it's piled up, but once you spread it, it's barely visible and won't suppress weeds. Many people also forget to account for settling. Mulch compacts over time, especially in the first few weeks after installation, so it's worth ordering 10 to 15 percent extra if you want to maintain that 3-inch depth through the season.
A third mistake is piling mulch against tree trunks and plant stems. This creates a "mulch volcano" that traps moisture and can cause disease and pest problems. Mulch should sit 2 to 3 inches away from any trunk or stem. If you're ordering mulch for a large area with many trees and shrubs, account for these clearance zones when you calculate your square footage.
When to order mulch and how to store it
Mulch is typically delivered in spring (March through May) when most people are preparing garden beds, and again in fall (September through November) for seasonal cleanup. Spring is the busier season, so if you're ordering in April or May, place your order early — some suppliers run out or have longer delivery times. Fall mulch is useful for insulating beds before winter and suppressing winter weeds.
If your mulch is delivered before you're ready to spread it, pile it in a location where water can drain away — wet mulch can heat up and smell bad if it sits in a pile for weeks. Mulch stored in a pile will settle and compact, so the pile will look smaller after a few days. This is normal and doesn't mean you received less than you ordered. Spread mulch within a week or two of delivery if possible, especially in warm weather.
Frequently Asked Questions
How many square feet does one yard of mulch cover?
One yard covers 108 square feet at 3 inches deep, 81 square feet at 4 inches deep, or 162 square feet at 2 inches deep. The depth you choose depends on your weed suppression needs and how long you want the mulch to last before needing a top-off. Most landscapers recommend 3 inches as the standard.
Is 2 inches of mulch enough?
Two inches provides light weed suppression and some moisture retention, but it's on the thin side. Three to 4 inches is more effective for blocking weeds and keeping soil moist. If budget is tight, 2 inches is better than nothing, but plan to add more the following year.
Can I use mulch in vegetable gardens?
Yes, mulch works well in vegetable gardens for the same reasons it works in flower beds — it suppresses weeds and retains moisture. Keep it 3 inches away from plant stems to prevent rot and pest problems. Avoid mulch treated with dyes or chemicals; use natural hardwood or straw instead.
How often do I need to add more mulch?
Hardwood mulch typically lasts 2 to 3 years before it breaks down enough to need topping off. Pine bark lasts about 1 to 2 years. In year two or three, you usually only need to add 1 to 2 inches rather than replacing it all, since the original layer is still partially intact underneath.
What if I order too much mulch?
Extra mulch can be stored in a dry location for next season, though it will settle and compact. You can also spread it thicker than planned (up to 4 inches), use it in other beds, or offer it to a neighbor. Some suppliers accept returns within a short window, so ask about their policy before ordering.