Mulch Calculator

Not this site's numbers. Lawn Love, how much does mulch cost, Written by Janine Caayao, published 27 December 2025 and read here on 2026-09-09.

Source: Lawn Love, how much does mulch cost, published 27 December 2025, read 2026-09-09. Priced by volume, which is how mulch is sold, so these figures apply directly to the cubic yards above with no density needed. Two things to read carefully. The single-figure rows are the publisher's averages for materials AND labour, not ranges, so they are shown as point values rather than dressed up as a spread. And its installed figure of 72 to 87 is NARROWER at the top than its own material-only figure of 30 to 135, so cypress material at 135 already exceeds the installed average: the rows are not all on one basis and cannot be added together.

This site publishes no price of its own. Why, and what that means for these figures.

A cubic yard is 27 cubic feet. A cubic foot spread one inch thick covers 12 square feet. So a cubic yard at one inch covers 27 × 12 = 324 square feet, and there is no judgement in it anywhere. Clemson states the same thing:

There are 27 cubic feet in a cubic yard. One cubic yard will cover a 324-square-foot area with an inch of mulch.

Multiply your square footage by the depth desired (in inches) and divide by 324 square feet. This will tell you how many cubic yards you will need.

Every coverage figure you will ever see for mulch is 324 divided by the depth. That is the whole calculation. Two inches is 162 square feet, three inches is 108, four inches is 81.

Which makes it easy to check whether a page has done its own arithmetic. The cost source quoted further down this page states both a two inch and a three inch figure:

Its two inch figure is exact to the square foot. Its three inch figure is rounded down to a friendly hundred and is short by most of a square yard per cubic yard ordered. Neither is dishonest and one of them is wrong, which is a fair summary of the genre.

Every mulch calculator gives you a depth slider and lets you drag it wherever you like. Clemson's factsheet does not treat depth that way. It sets a maximum by the texture of the material, and the reason is not thrift:

Many wood and bark mulches are composed of fine particles and should not be more than 2 to 3 inches deep. Excessive amounts of these fine-textured mulches can suffocate plant roots, resulting in yellowing of the leaves and poor growth.

Suffocate. Not waste, not overspend. Too much fine-textured mulch closes the surface and the roots under it stop getting air. The other two textures get their own limits and their own reasons:

Coarse-textured mulches such as pine bark nuggets allow good air movement through them and can be as deep as 4 inches.

Mulches composed of grass clippings or shredded leaves should never be deeper than 2 inches, because these materials tend to mat together, restricting the water and air supply to plant roots.

Read the second column against the third. Coarse nuggets are permitted twice the depth of grass clippings, so a cubic yard of nuggets covers 81 square feet where a cubic yard of clippings has to be spread over 162. The material you pick changes the order by a factor of two before anybody measures the bed.

The calculator above warns when the depth you enter is deeper than the published maximum for the material you picked. It still gives you the volume, because it is your garden. It just will not pretend the figure is fine.

Most materials on this site carry a waste allowance because they are cut: offcuts, rips at the wall, mitres that go wrong. Mulch is not cut, so most of the usual sources of waste do not exist.

What is left is spillage from the barrow, the material that goes on the path and gets swept back, settlement over the first few weeks, and the bit at the bottom of the pile mixed with the driveway. The default here is 5%, it is ours rather than anybody's standard, and it is an input.

Set it to zero if you are buying bags, because you can go and get one more, and the bag you did not open goes back. Bulk delivery is where the allowance earns its place: a short load means a second delivery charge for a fraction of a yard.

Do not confuse waste with settlement. Organic mulch loses depth over a season as it breaks down, and topping up next spring is a normal part of owning it rather than an error in this year's order. The factsheet puts bark and pine needles at around two to four years before the bed needs rebuilding rather than topping.

Beds are rarely rectangles and the circle mode is there for the case that matters most: the ring around a tree.

The factsheet's rule for an established tree is a mulch circle about 2 ft in diameter for every inch of trunk diameter, which is much larger than the neat little collar most people cut. A 6 in trunk asks for a 12 ft circle. A 10 in trunk asks for 20 ft, which is 314 square feet and, at 3 in, close to three cubic yards for one tree.

For an irregular bed, split it rather than averaging it. Run the rectangle mode on the parts that are roughly rectangular, run the circle mode on the round ends, and add the cubic yards. Averaging a curved bed into one rectangle is where the ordering error usually comes from, and it errs short about as often as long.

A long thin border is the easy case and the one people get wrong in the other direction: 2 ft wide and 60 ft long is 120 square feet, which at 3 in is barely more than a cubic yard. Below about a yard, most yards will not deliver, and bags win by default rather than on price.

The same factsheet sets three clearances, and each has a failure mode behind it rather than an aesthetic:

Keep mulch 2 to 3 inches away from the stems of woody plants. This will prevent decay caused by wet mulch and rodent damage during the winter. Keep mulch 6 to 12 inches away from the walls of buildings.

2 to 3 inches from the stems of woody plants. Wet mulch held against bark rots it, and the gap is also what stops voles overwintering against the stem and ring-barking the plant under the snow.

6 to 12 inches from the walls of a building, and this one is the expensive one. The source is explicit about why: soil termite treatment is applied to the ground around the building, and a bed of cellulose piled over it is a bridge across the treated band.

And on trees:

Newly planted trees require a circle of mulch 3 to 4 feet in diameter; however, do not pile mulch against the trunk. For established trees in lawns create a circle of mulch about 2 feet in diameter for each inch of trunk diameter.

2 feet of ring diameter for every inch of trunk diameter is a bigger circle than most people picture. A 6 in trunk asks for a 12 ft circle, which is 113 square feet, and at a 3 in depth that is 1.05 cubic yards for one tree. The calculator has a circle mode for exactly this.

Do not pile it against the trunk. The cone of mulch heaped up a trunk is the single most common mulching error in the country, and the factsheet rules it out in six words.

A cubic yard is 27 cubic feet, so at the usual 2 cubic foot bag it is 13.5 bags. That single conversion decides the whole bags-or-bulk question and it is almost never printed next to the prices.

Run it against the quoted figures below. Bagged mulch is priced per bag and bulk is priced per cubic yard, so multiply the bag price by 13.5 before comparing anything. At the bottom of the bagged range that is under the bulk material minimum; at the top of it, it is well over the top of the bulk range. Bags are not reliably dearer or cheaper, they are more variable.

Two things bags do buy you. No delivery charge, which the source prices separately per load, and no minimum order, which is the real constraint on a small bed. A yard that will not deliver under three cubic yards has made the decision for you.

And the bag size is the thing to check. The calculator above lets you set it, because 2 cubic feet is common rather than universal and the difference between a 2 and a 3 cubic foot bag is a third of your bag count.

Read 2026-09-09. Mulch, Home and Garden Information Center factsheet HGIC 1604, Clemson Cooperative Extension. Original authors Marjan Kluepfel and Robert F. Polomski. Originally published 04/99, revised 20 June 2016. Sets a MAXIMUM depth by the texture of the material rather than a recommended one, and states the 324 square feet per cubic yard per inch relationship in those words. Also gives the clearances from stems and from building walls, and the mulch-ring rule for trees.

It is a state extension factsheet rather than a code, so nothing here is enforceable and none of it is a span table. What it is, is horticulture published by a land-grant university with named authors and a revision date, which is a different class of thing from a landscaping blog repeating a depth it read somewhere.

What it does not give is a weight. Mulch is sold by volume, so this page needs no density and does not print one, but if you are hiring a skip or checking a trailer axle rating you will want one and it is not here. The same problem as aggregate: what a heap weighs is a property of the heap.

It also does not set a replacement interval beyond noting that pine needles and bark mulches typically last for around 2 to 4 years before the need to add more. Inorganic mulches such as gravel and pebbles rarely need replenishing. That is a range across two species groups, not a schedule.