Mulch Calculator

Multiply the area of your bed by the depth you want, in matching units, to get a volume, then divide by 27 to convert cubic feet into cubic yards, since that is how mulch is priced and delivered. This calculator runs that step directly for a rectangle, circle, ring, triangle or trapezoid, or a straight area entry if you already know the square footage, and adds up multiple beds if you have more than one. Pick a mulch type first, since the depth field fills in with a sensible default for that material, then read the volume, bag count and weight off the results.

About 1 cubic yard at a typical 3 inch depth, which is 14 bags at the standard 2 cubic foot bag size. That figure comes directly from Colorado State University Extension's own coverage chart, which states that one cubic yard covers roughly 100 square feet at 3 inches deep. Change the depth or the area in the calculator above and the number moves with it; this is just to show the shape of the math on a round figure.

Volume equals area multiplied by depth, in matching units. For a rectangular bed that is length times width times depth; the calculator above runs the equivalent formulas for circles, rings, triangles and trapezoids automatically. Convert the result to cubic yards by dividing cubic feet by 27, since mulch is bought and delivered by the cubic yard in most of the United States. The arithmetic is simple; the part people get wrong is the depth and the area, not the formula itself.

Most guidance lands between 2 and 4 inches, with the exact figure depending on the material. Iowa State University Extension recommends 2 to 3 inches for fine, shredded mulch and 3 to 4 inches for coarser chipped or nugget mulch, since bigger pieces need more depth to close the gaps between them. Colorado State University Extension gives 3 to 4 inches as a general figure for most mulches, and 4 to 6 inches specifically for straw and loose leaves, which settle and compact more than wood does. This calculator sets its default depth per material to match that guidance, and the field stays editable for your own site conditions.

The same 2 to 4 inch range that answers how deep mulch should be, but the more useful fact is the upper limit: more than 4 inches starts to work against you, holding too much moisture against bark and roots and cutting off the air and water exchange the soil needs. Straw and loose leaves are the exception, since Colorado State University Extension allows 4 to 6 inches for those specific materials because they compact down so much faster than wood mulch does.

Calculate above and read the bag count straight off the results, at either 2 cubic foot or 3 cubic foot bags, whichever size your supplier sells. The panel also shows the equivalent bulk cubic yardage next to it, so you can compare the two without a separate conversion. Past about 3 cubic yards, which is already more than 160 bags at the 2 cubic foot size, bulk delivery is almost always the better choice on price and effort.

14 bags at the common 2 cubic foot size, or 9 bags at 3 cubic feet. A cubic yard is 27 cubic feet by definition, so the bag count is that figure divided by the bag size and rounded up, 13.5 rounding up to 14 for a 2 cubic foot bag, so you never come up half a bag short.

27 cubic feet in a cubic yard, the same conversion that applies to any material sold by the yard, not just mulch. It is the number behind every bag count on this page: divide 27 by your bag size in cubic feet, then round up, to see how many bags one cubic yard takes.

It depends heavily on the material and how wet it is, which is why this is one of the least precise figures in mulch math. For wood chips specifically, the U.S. EPA's Standard Volume to Weight Conversion Factors report gives 243 pounds per cubic yard dry and 473 pounds per cubic yard green, meaning freshly chipped and still wet, which works out to roughly 18 to 35 pounds for a 2 cubic foot bag of that material. Denser materials such as compost or rubber mulch weigh noticeably more per bag; the calculator above shows a weight range for whichever material you pick.

For wood chips, roughly 18 pounds dry to 35 pounds green, meaning freshly chipped and still wet, scaling the U.S. EPA's cubic yard figures of 243 to 473 pounds down to a 2 cubic foot bag. Other mulch types run lighter or heavier depending on density; shredded bark and hardwood are typically in a similar range, while compost and rubber mulch are considerably heavier per bag.

For wood chips, 243 pounds dry to 473 pounds green, meaning freshly chipped and still wet, according to the U.S. EPA's Standard Volume to Weight Conversion Factors report, roughly double between the dry and wet ends of the same material. Decorative bark and hardwood mulches do not have an equivalent government figure, so treat any weight quoted for them, including the ranges in the calculator above, as a working estimate rather than a lab measurement, and expect the number to climb after rain.

A standard 2 cubic foot bag covers about 8 square feet at a 3 inch depth, which comes from dividing the 2 cubic feet by 0.25 feet of depth. At 2 inches deep the same bag covers about 12 square feet; at 4 inches, about 6 square feet. Coverage scales directly with depth, so halving your depth roughly doubles what one bag covers.

According to Colorado State University Extension's own coverage chart, about 325 square feet at 1 inch deep, 160 square feet at 2 inches, 100 square feet at 3 inches, and 80 square feet at 4 inches. Those figures are close to the pure geometry of 27 cubic feet divided by the depth, rounded for a practical delivery order rather than a lab measurement. Use the calculator above with your own depth if it falls outside those four common figures.

One cubic yard is 27 cubic feet, roughly the volume of a cube just over 3 feet on each side, though mulch is never actually piled as a cube. Spread out, that same cubic yard covers about 100 square feet at a typical 3 inch depth, which is a clearer way to picture it than the raw volume, since almost nobody measures a mulch bed in feet of height.

This calculator will not give you one fixed price, deliberately, since cost swings by material, region and supplier in a way that cannot be stated as a single reliable figure the way a depth recommendation can. What it does instead is pre fill a starting price per bag and per cubic yard for whichever material you pick, both fully editable, so you can drop in your own supplier's price and get an exact total rather than a market guess.

Enter your own bulk price per cubic yard in the calculator above for an exact figure. Bulk delivery pricing varies by material, region and how far a supplier has to haul it, so there is no single number that holds true everywhere; the calculator pre fills a starting estimate per material and lets you replace it with your supplier's actual quote.

Bulk, past about 3 cubic yards. That threshold is already more than 160 bags at the 2 cubic foot size, which costs more per yard than bulk delivery and takes several trips to move by car. Below that threshold, bags are usually the more practical choice even where bulk works out slightly cheaper per yard, since there is no minimum order or delivery to arrange for a small job.

Break it into simple shapes and add them as separate areas rather than trying to force one measurement over an odd outline. An L shaped bed is two rectangles; a bed that wraps around a tree is a ring; a curved border close enough to a triangle or trapezoid can use those shapes directly. The calculator above totals as many areas as you add, so there is no need to average an irregular shape into a single guessed rectangle.

Add each bed as its own area in the calculator above rather than running the tool separately for each one and adding the results by hand. Every area can be a different shape and size; the mulch type and depth apply across all of them, and the results total the volume, bags and weight for the whole project in one pass.

Fine, shredded mulch such as natural or dyed hardwood is recommended at 2 to 3 inches, while coarser material such as pine bark nuggets or wood chips is recommended at 3 to 4 inches, since larger pieces need more depth to close the gaps between them, per Iowa State University Extension. Compost or leaf mulch is the exception in the other direction, kept to 1 to 2 inches because it is dense and fine enough to compact and smother roots if piled as deep as a wood based mulch.

The same calculator, not a separate one, select pine bark nuggets from the material list above rather than shredded hardwood. Bark nuggets are recommended a little deeper than shredded mulch, 3 to 4 inches rather than 2 to 3, since the larger pieces leave more gap between them that needs filling.

They cover the same area at the same depth, since dyed mulch is simply natural hardwood mulch with color added, not a different material. The real tradeoff is appearance over time: the dye fades after a season or two of sun and rain, while natural hardwood just weathers to a grayer brown, so the choice comes down to whether you are willing to refresh color periodically rather than anything about how much you need to buy.

There is no fixed calendar date, since it depends on climate and material rather than time alone. Both Utah State University Extension and Colorado State University Extension describe the same practical rule: organic mulch breaks down and needs replenishing once it has visibly thinned or turned gray, while inorganic mulch such as rubber does not decompose and only needs replacing when it is physically removed or contaminated.

Leave a few inches of mulch free space right at the base, according to Utah State University Extension, since piling mulch against bark traps moisture and encourages the root and stem diseases a mulch layer is meant to help prevent, the mistake commonly called a mulch volcano. Colorado State University Extension is more specific about straw and loose leaves in particular, recommending they stay at least 6 inches back from the trunk, since rodents living in that kind of mulch will chew bark close enough to reach it.

Yes. Every measurement field accepts metric or imperial units and converts automatically, and the headline result switches between cubic yards and cubic meters depending on which system is selected, with liters and cubic feet shown alongside either way. The depth and density figures behind the numbers are the same sourced guidance regardless of which units you use, only the displayed units change.

The material, and therefore the depth and the weight, not the underlying math, since all three run the same area times depth formula. Mulch sits on top of soil at a shallow 2 to 4 inches and is far lighter per cubic yard than either soil or gravel. If you are filling a raised bed or amending planting soil rather than topping a bed, use the Soil Calculator or Topsoil Calculator instead; if you are building a base or a path that needs to bear weight, use the Gravel Calculator, which accounts for compaction in a way mulch never needs to.