Material takeoff
How much mulch do I need?
Enter your bed size and how deep you want the mulch. You get cubic yards for bulk delivery and bag counts for the store run.
How the math works
Mulch is a volume, so depth matters as much as area. The whole calculation is one line:
cubic yards = square feet × depth in inches ÷ 324
That 324 is worth remembering. One cubic yard spread one inch deep covers 324 square feet. At two inches it covers 162 square feet, at three inches 108, at four inches 81. If you only remember one number for landscaping math, make it that one.
How deep should mulch be?
Three inches is the standard for established beds. It's deep enough to suppress weeds and hold moisture, shallow enough to let water and air through.
Two inches is right for beds you're topping up rather than starting fresh, and for areas with fine-textured mulch that packs down.
Four inches is for new beds with bare soil and a weed problem, or for coarse mulch like pine nuggets that settles a lot.
Past four inches you're wasting money and starting to cause problems. Deep mulch stays wet, and mulch piled against trunks and stems invites rot and rodents. Pull it back a few inches from anything living.
If you are covering a play area rather than a garden bed, the depths are completely different — see the playground mulch calculator.
Where people get it wrong
- Measuring the bed as a rectangle
- Most beds curve. A kidney-shaped bed measured as its bounding rectangle can be 30% oversized. Trace the real outline if you can.
- Forgetting existing mulch
- If last year's mulch is still two inches deep, you need one more inch to reach three, not three more.
- Buying bags for a bulk job
- Around three cubic yards, bulk delivery usually beats bags on price and always beats them on effort. Three cubic yards is 41 bags.
- Ignoring settling
- Coarse mulch settles noticeably in the first month. Order at the depth you want it to end up, then add the waste allowance.
Background
Mulch is sold two ways and the units don't match, which is where most of the confusion starts. Bulk mulch comes by the cubic yard, delivered loose or shoveled into your truck. Bagged mulch comes in 2 cubic foot bags, and there are 13.5 of them in a cubic yard. If your beds total more than about three cubic yards, bulk is almost always cheaper and one less trip.
What you need for the job
Common questions
How many bags of mulch are in a cubic yard?
13.5 bags at 2 cubic feet each, since a cubic yard is 27 cubic feet. If your bags are 1.5 cubic feet, it takes 18 of them.
How much does a cubic yard of mulch cover?
At 3 inches deep, one cubic yard covers about 108 square feet. At 2 inches it covers 162 square feet, and at 4 inches about 81 square feet.
How much mulch do I need for 500 square feet?
At 3 inches deep, about 4.6 cubic yards, or 63 two-cubic-foot bags. Add roughly 10% for uneven ground and settling.
How much does a yard of mulch weigh?
Usually 400 to 800 pounds depending on the material and how wet it is. Wet hardwood mulch is at the heavy end, and most half-ton pickups should not take more than one yard at a time.
Should I put landscape fabric under mulch?
Under stone, generally yes. Under organic mulch it is more debatable, because the mulch breaks down into soil on top of the fabric and weeds root in that layer anyway. Many landscapers skip it in planting beds and use it only under gravel. See the landscape fabric calculator for roll counts.
Measuring by hand is where estimates go wrong
Trace your beds, driveway, or lawn on satellite imagery and the square footage comes straight from the shape you drew. Subtract the house and driveway, map every project on the property at once, and get one combined order list.
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