How much mulch do I need?

The arithmetic, in one line

Area in square feet, times depth in feet, divided by 27. That gives cubic yards, which is the unit bulk suppliers sell in.

Depth in inches divided by 12 gives depth in feet. So 9 inches is 0.75 feet and 12 inches is 1 foot. A 500 square foot use zone at 12 inches is 500 cubic feet, which is 500 divided by 27, or 18.5 cubic yards. The same area at 9 inches is 375 cubic feet, or 13.9 cubic yards.

Two numbers come before the arithmetic, and both are worth getting right before you price anything.

1. The area. Measure the whole use zone, not the footprint of the equipment. Swings in particular need surfacing to twice the pivot height in front and behind, which is often more area than the rest of the structure put together. Fall height and use zones shows how the boundary is drawn.
2. The depth. Depth follows the fall height of the tallest designated play surface, using the CPSC loose-fill figures¹. The depth and fall height chart has the full grid.

What a cubic yard actually covers

A cubic yard is 27 cubic feet, so its coverage is 27 divided by the depth in feet.

The 6 inch line is why rubber looks better on a delivery ticket than it does on an invoice. It needs half the volume of wood fiber for the same use zone, which takes the sting out of a much higher price per cubic yard. Rubber mulch runs that comparison properly, including the parts that are not about volume.

Quantity by area

The table below is straight arithmetic: area divided by 36 for a 9 inch installed depth, area divided by 27 for a 12 inch installed depth. Neither column includes waste.

Add the waste allowance to the order rather than to a mental note. Running short by two cubic yards on the last afternoon costs a second delivery fee and a second mobilization, which is usually more than the material you were trying not to over-buy. The surfacing depth calculator does this against a real use zone, and the mulch quantity calculator handles the bag and yard conversions.

Delivery minimums, truck sizes and access

Bulk suppliers sell by the cubic yard and most set a minimum. In 2026 US practice that minimum is commonly 3 to 10 cubic yards for a local delivery, with a delivery charge of roughly $75 to $250 inside a normal radius and more beyond it. Long hauls are sometimes quoted per loaded mile.

What arrives depends on volume. Loose wood fiber is bulky and light, so trucks hauling it usually run out of space long before they run out of legal weight.

For a 400 square foot backyard job at 12 inches you are in single-truck territory. For a 2,000 square foot school playground at 12 inches you are near 74 cubic yards, which is a walking floor trailer or five to seven tandem loads, and it needs a staging area and a plan for moving material across the site.

Weight, and why it matters

Density varies with material and moisture, so treat these as planning ranges rather than fixed figures. Engineered wood fiber typically runs about 400 to 800 pounds per cubic yard, heavier after rain. Shredded rubber is broadly similar per cubic yard but needs half the depth. Sand is in a different category at roughly 2,200 to 2,900 pounds per cubic yard, which is why a sand delivery that looks small on a ticket can overload a small truck and a small crew.

Two practical consequences. A 15 cubic yard wood fiber delivery is several tons of material to move by wheelbarrow, so plan the labor. And if the pile has to sit on a lawn or a deck for a day, put it on tarps and expect to pay for the grass either way.

Bulk versus bagged in 2026

Bulk delivered engineered wood fiber commonly runs $25 to $60 per cubic yard in 2026 US pricing for volume orders inside a local delivery radius, before the delivery fee. Bagged playground-grade wood fiber at 2 cubic feet per bag is commonly $4 to $9 a bag, which is roughly $54 to $122 per cubic yard once you multiply by the 13.5 bags a cubic yard takes. Rubber mulch is higher in both formats and moves with scrap tire markets.

The crossover is early. Past roughly three or four cubic yards, bulk wins on price even after the delivery charge. Bags still make sense in three cases: a small top-up under a swing, a site with no truck access, or a job where the material has to be carried through a house or down a narrow side path.

Put the material figure next to the rest of the job before you decide anything. The surfacing cost calculator prices the full area, and surfacing cost comparison sets wood fiber against rubber and poured systems over a full service life.

Spreading: time, tools and crew

Moving and leveling loose fill is slower than people expect. A reasonable planning figure for one person with a wheelbarrow, a shovel and a landscape rake is 1 to 2 cubic yards per hour over a short haul on flat ground, dropping sharply once the haul gets long, the ground slopes or a gate narrows the route.

Fifteen cubic yards is therefore most of a day for two people, and a 74 cubic yard school job is a machine job: a skid steer or compact tracked loader with a crew raking behind it. What you need on hand:

• Wheelbarrows, one per person moving material, plus a spare wheel
• A wide landscape rake for leveling and a stiff broom for edges
• Depth markers or a marked stake in each high wear area
• Plywood or boards to protect turf and paving on the haul route
• A hose, because wetting wood fiber helps it knit and settle evenly

What to do next

Get the area right first, because area is what makes quotes surprising, not depth. Then set the depth from fall height, apply the settling allowance, add waste, and check the number against the delivery minimum before you call.

If the volume looks alarming, the fix is usually the same one that fixes the budget: a lower deck, a tighter use zone or a smaller footprint. If the site is a backyard, backyard surfacing covers what changes at small scale. Before the first load arrives, make sure the excavation, edging and base are ready, because dumping loose fill onto unprepared ground wastes a portion of every delivery. Drainage and base layers and site prep and leveling cover that work, and surfacing upkeep sets the top-up rhythm that starts the day you finish.