Mulch Calculator - Cubic Yards, Bags & Cost

How to use it

1. Pick the material first. It sets the depth, the density, the bag size and a price band, and every one of those stays editable because your yard is not our yard.
2. Name each bed the way you would say it out loud: front bed, side strip, maple ring. The list should read like the walk around your garden.
3. Choose the shape, then put feet and inches in their own boxes. A 12 ft 7 in border goes in as 12 and 7, never as 12.7.
4. Set the target depth from the chips, or type your own. Three inches is the working default for shredded mulch, four for coarse nuggets and chips.
5. This is the important one: enter how much mulch is already down. An inch of last year's layer under a 3 in target means you buy 2 in, and the page shows you what that saves.
6. Read the four numbers in order: what you measured, what you buy once waste is in, what to actually ask the supplier for, and how many bags that is instead.
7. Open the bags versus bulk ledger and put your real bag price, yard price and delivery fee in. The crossover moves a long way with a waived delivery.
8. Check the weight and the trips before you decide how it gets home. Mulch fills a pickup bed before it troubles the axle, which is the opposite of gravel.

At a glance

• The seeded three beds, topped up over last year's inch: 203.5 sq ft in three beds, an inch already down: 31.62 cu ft, which is 1.17 cu yd measured and 1.23 with waste. Order 1.5 cu yd, or 17 bags.
• The same three beds treated as fresh: 48.58 cu ft, 1.80 cu yd measured and 1.89 with waste. Order 2.0 cu yd, or 26 bags. The inch already down is worth half a yard and 9 bags.
• How many bags of mulch in a cubic yard: 13.5 of the 2 cu ft bags, 9 of the 3 cu ft, 18 of the 1.5 cu ft and 33.75 of the 0.8 cu ft rubber bags. A yard is 27 cu ft, so divide 27 by the bag size on the label.
• How far one cubic yard goes: 324 sq ft at 1 in, 162 at 2 in, 108 at 3 in, 81 at 4 in and 54 at 6 in. The rule is 324 divided by the depth in inches.
• 800 sq ft of natural area, two ways: Hardwood at 3 in is 8.0 cu yd delivered, about $395 and 4,800 lb. Pine straw is 20 bales at 40 sq ft each, about $130 and 300 lb.

How the math works

Every length is held in inches, so feet and inches never have to be merged in your head. Each bed becomes square feet by its own formula: a rectangle is length times width, a circle is pi times the diameter squared over four, a tree ring is the outer circle minus the clear centre, and a triangle is base times height over two. The depth you buy is the target depth minus what is already down, floored at zero, which is the whole point of the page. Volume in cubic feet is area times that buy depth divided by 12, and the divide by 27 into cubic yards happens once, at the end. Waste multiplies the measured figure: 5 percent covers the ragged edges of a real bed, and rubber defaults to zero because it neither settles nor rots. The order figure rounds up to the step your supplier loads in, a quarter yard, a half or a whole one. Bag count is the buy volume in cubic feet divided by the bag size, rounded up, and the leftover is what you carry back. Coverage is 324 divided by the depth in inches for a yard, and the bag size times 12 divided by the depth for a bag. Weight is cubic yards times an editable density with its honest range printed beside it. The bags versus bulk verdict multiplies the bag price by 27 over the bag size before it compares anything, then finds the crossover as the delivery fee divided by the per yard gap. Pine straw skips volume entirely, because bales are sold by coverage: bales are the total area divided by the coverage one bale gives, rounded up. Finally, the per bed rows you read are apportioned against the printed totals using largest remainder, so the column always adds to the figure it sits under, and the waste row is the exact difference between the two printed totals rather than a separately rounded number.

1. Measure the beds, and measure the ring as a ring

   Area first, depth second, because they come from different places. Take the tape round the beds you are actually mulching. A border around a tree is a ring, not a circle: a 6 ft ring with a 1 ft clear centre at the trunk is 27.5 sq ft, not the 28.3 sq ft of the full circle, and the clear centre is not decoration, it is the gap that keeps the trunk alive. For a kidney shaped bed, take the biggest rectangle you can inside it and add the leftovers as their own rows.

2. Set the depth from the job, not from habit

   Fine shredded mulch works at 2 to 3 in. Coarse nuggets and arborist chips need 3 to 4 in, because the gaps between the pieces let light through at anything shallower. Weed suppression starts at 3 in and is reliable at 4. Above 4 in you are smothering roots rather than protecting them, and mulch piled against stems and trunks is how mulch kills plants. Playground depths are a different question entirely and the chip says so.

3. Subtract what is already down, because you are not buying it twice

   This is the step every other calculator skips. Push a finger into an established bed: if there is an inch of last year's mulch still there, a 3 in target means you buy 2 in, which is a third less material. On 400 sq ft that is the difference between 2.5 cubic yards and 4.0, or between 34 bags and 50. The page computes both and prints the fresh-bed answer struck through, so the saving is visible rather than theoretical.

4. Add waste for the edges, not for the arithmetic

   Five percent covers what a real bed loses that a rectangle does not: ragged edges, the wheelbarrow tipping, raking around plants, and the settling that fluffy fresh mulch does in its first week. It is not a fudge factor for bad measuring. Rubber gets zero because it does not settle or decompose, and pine straw gets none either because bales are sold by coverage with the fluffing already accounted for.

5. Round to the step the yard actually loads in

   A loader bucket is a fixed size. Most suppliers sell in half yard steps with a one yard minimum, some only in whole yards, and a few will do quarters. Rounding 1.23 cubic yards up to 1.5 is not waste, it is the smallest thing they will sell you. Rounding down leaves you short, and a second delivery for half a yard costs the whole delivery fee again.

6. Compare bags to bulk in the same unit before you decide

   A $4.50 bag looks cheap next to a $40 cubic yard until you notice that a yard is 13.5 of those bags, which is $60.75. Bulk is always cheaper per yard. What keeps bags competitive is the delivery fee, which is a fixed cost spread over however much you order. At $4.50 bags, $40 bulk and a $75 delivery, bulk delivered only overtakes bags at about 3.6 cubic yards. If you can collect it yourself, bulk wins from the first yard.

7. Check the weight, then decide how it gets home

   Mulch is the light one. At 600 lb a cubic yard, a half ton pickup rated at 1,500 lb could carry 2.5 yards on payload alone, so the bed fills before the axle complains and volume governs the trip. Rubber flips it: at 1,180 lb a yard the payload runs out at 1.27 yards and the bed is still half empty. Either way, a 2 cu ft bag of hardwood is about 44 lb, which is the number that decides whether this is one car trip or four.

Worked scenarios, start to finish

Real jobs with the numbers carried all the way through, so you can see how the estimate is built and check your own figures against them.

The judgement calls a pro makes

Decisions the tool cannot make for you, and how someone who does this for a living thinks them through.

How deep, and when deeper stops helping

Depth is set by how coarse the mulch is and what you want it to do. Fine shredded material blocks light at 2 in and mats down, so 2 to 3 in is right and more just holds water against stems. Coarse nuggets and arborist chips have gaps, so they need 3 to 4 in to do the same job. Weed suppression is the one that genuinely needs 3 in minimum and works properly at 4. Past 4 in you are into diminishing returns and real risk: mulch that deep stays wet, keeps soil cold late into spring and starves shallow roots of air. If a bed already has 3 in, the right order this year is nothing.

Keep it clear of stems and trunks. This is not a detail

The mulch volcano, that neat cone piled up the trunk of a street tree, is the most common way landscaping kills trees. Bark held permanently wet rots, girdling roots grow into the mulch instead of the soil, and rodents nest in it and chew the bark over winter. Leave 2 to 3 in of clear space around trunks and stems, and spread the ring wide and flat rather than tall. A ring that reaches the drip line at 3 in beats a cone at 8 in in every way that matters, and costs less.

Bulk or bags: the delivery fee decides, not the price per yard

Bulk is always cheaper per cubic yard, often by a third to a half. What keeps bags in the game is that they carry no delivery fee, no pile on the drive and no deadline. Under about two yards bags usually win outright at typical prices. Between two and four it is close and it comes down to your fee. Above four, bulk wins clearly. Then there is everything the numbers do not say: bags let you do a bed a weekend, they do not stain a driveway, and they get through a side gate that a loader cannot. The ledger on this page takes your real prices, so run it before you assume.

Landscape fabric belongs under stone, not under organic mulch

Fabric under gravel is doing a real job: it stops the stone from disappearing into the soil. Under bark or chips it fights the entire purpose, which is to break down into the soil and feed it. Within two seasons the mulch above the fabric has rotted into a fine seed bed, weeds root in it happily, and now their roots are threaded through fabric you cannot pull up. Skip it, keep the layer at 3 in and top up annually. That is a cheaper and better weed strategy than anything you can staple down.

Free arborist chips, and when they are the right answer

Tree crews pay to tip chips, so many will drop a load free if you are on their route, and municipal yards often give them away. It is uneven, it contains leaves and green wood, and it looks like what it is. On paths, natural areas, under established trees and around a new orchard, it is the best value in the whole aisle. Keep it away from vegetable beds and new seedlings, because fresh chips tie up nitrogen at the soil surface for a season while they break down. And you get what arrives, when it arrives, in whatever species was being cut that day.

When to mulch, and why spring is not always the answer

Spring is the popular answer because that is when garden centres stock it, but mulch applied to cold wet soil in March keeps it cold and wet. Wait until the soil has warmed, usually mid to late spring, then mulch and the layer holds that warmth and moisture through summer. Late autumn is the other good window: after the ground has cooled, a fresh layer moderates the freeze and thaw cycles that heave shallow perennials out of the ground. Mulching over frozen ground or bone dry soil does nothing useful either way.

Common mistakes, and the fix

• × Buying the full target depth for a bed that already has last year's mulch in it.

  ✓ Check the existing depth with a finger and enter it. On 400 sq ft with 1 in already down and a 3 in target, the honest order is 2.5 cubic yards rather than 4.0, and 34 bags rather than 50. That is $60 to $72 saved and a third less lifting, and the page prints both numbers so you can see the gap.

• × Comparing a bag price to a bulk price without converting them to the same unit.

  ✓ Multiply the bag price by 13.5 for a 2 cu ft bag, or by 9 for a 3 cu ft bag, before you compare it with a per yard price. A $4.50 bag is $60.75 a cubic yard. Bulk at $40 with a $75 delivery only actually beats it above about 3.6 yards, and if you collect it yourself bulk wins from the very first yard.

• × Assuming every bag is 2 cubic feet.

  ✓ It is the most common size for wood mulch and it is far from universal. Rubber usually comes in 0.8 cu ft bags because a 2 cu ft bag of it would weigh 87 lb, some brands sell 1.5 cu ft, and 3 cu ft bags exist for bulk buyers. Read the size off the label and put it in the bag size box, because a 25 percent error in bag size is a 25 percent error in the order.

• × Mulching at 1 in for weed control.

  ✓ One inch stops nothing. Light gets through, weed seed germinates in it and you are weeding by June. Weed suppression needs 3 in minimum and works properly at 4 in with a coarse material. If your budget only reaches 1 in across everything, mulch half the beds properly this year and the rest next year instead.

• × Trusting "a yard covers 100 square feet" with no depth attached.

  ✓ A cubic yard does not cover a fixed area. It covers 324 square feet at 1 in, 162 at 2 in, 108 at 3 in, 81 at 4 in and 54 at 6 in. The 100 sq ft figure on the yard's sign is true at about 3.2 in and nowhere else. Any coverage claim without a depth beside it is missing the only variable that matters.

• × Piling mulch against house siding and up over the weep holes.

  ✓ Keep mulch a few inches below the bottom of the siding and clear of any weep holes in brickwork, and leave a gap at the foundation. A permanently damp organic layer against the wall is an invitation to termites and rot, and it blocks the drainage path the wall was built with. Gravel is the better material in the strip right against the house.

• × Ordering by weight because the supplier quoted tons, then getting a wet load.

  ✓ Mulch is sold by volume for good reason: wet material weighs 10 to 20 percent more than the same volume dry, and rain does not add mulch. If a supplier prices by the ton, ask what a cubic yard of their material weighs on their scale and convert, and expect to pay more for the same coverage after a wet week.

Material and unit specifics

Density by type, in pounds per cubic yard

Pine bark nuggets are the lightest at about 450, cedar around 500, dyed wood and cypress about 550, shredded hardwood about 600 and arborist chips 550 or heavier depending on how green they are. Rubber is in a different class at about 1,180. Every one of those is a dry figure and a range, because species, grind and moisture all move it, and wet material runs 10 to 20 percent heavier. The density field on this page is editable and prints its honest range beside it.

Bag sizes and what a yard costs in bags

A cubic yard is 27 cubic feet, so it is 13.5 bags at 2 cu ft, 9 bags at 3 cu ft, 18 at 1.5 cu ft and 33.75 at the 0.8 cu ft size rubber comes in. The 13.5 figure is the one worth memorising: it is what turns a bag price into a per yard price. A 2 cu ft bag of hardwood weighs about 44 lb, which is also why 26 bags is a different afternoon from one delivered pile.

Coverage from one cubic yard and from one bag

One cubic yard covers 324 sq ft at 1 in, 162 at 2 in, 108 at 3 in, 81 at 4 in and 54 at 6 in. One 2 cu ft bag covers 24 sq ft at 1 in, 12 at 2 in, 8 at 3 in and 6 at 4 in. A 3 cu ft bag covers 36, 18, 12 and 9 at the same depths. Both tables come from the same rule: volume in cubic feet times 12, divided by the depth in inches, gives square feet.

Pine straw, sold by coverage rather than volume

Straw is baled, and a bale fluffs out to a settled layer of roughly 3 in. Coverage runs 30 to 50 sq ft a bale depending on bale size and whether it is long leaf or slash pine, so the coverage figure is the input that actually decides your order and the one to confirm with the seller. It is the cheapest way to cover a large area, it is light enough to carry by hand and it is acidic enough to suit azaleas and camellias, but it breaks down fast and needs refreshing about twice a year.

Rubber mulch, and the playground depth question

A 15 by 15 ft play area at 225 sq ft, mulched to 6 in, is 112.5 cubic feet, which is 4.17 cubic yards. In the 0.8 cu ft bags rubber usually comes in, that is 141 bags, about $1,692 at $12 a bag and roughly 4,900 lb. The CPSC Public Playground Safety Handbook lists 6 in of shredded rubber, or 9 in of engineered wood fibre, for protection at typical residential fall heights. Treat that as guidance to verify against the specific product's certification and your equipment's fall height, never as a safety promise from a calculator.

Dyed mulch and the colour cycle

Dyed mulch is usually ground pallet or scrap wood coloured with iron oxide for red and brown or carbon black for black. The pigment is not the problem people think it is, but the wood underneath often is: it is a manufactured product rather than bark, so it breaks down into less useful material. Colour holds about one season in full sun and up to two in shade, which means the annual top-up is really a re-dye. Budget for it every year rather than every two.

Wet weight, and when it actually matters

Rain adds 10 to 20 percent to the weight of a yard of mulch and nothing at all to its volume. So it never changes the order if you are buying by the yard, and it changes everything if you are buying by the ton, checking a trailer against its rating, or deciding whether a half ton pickup can take the whole load in one trip. Material that has sat in an open yard through a wet week is wet, so use the upper end of the range for those checks.

Cedar and cypress: paying more to buy fewer years

Cedar carries natural oils that slow rot, so a layer lasts two to three seasons against one for hardwood, and it is the lightest wood mulch to barrow. Cypress mats into an interlocked layer that holds a slope better than almost anything. Both cost roughly 20 to 40 percent more per yard than shredded hardwood. On a bed you top up every spring anyway the premium buys little, and on a low maintenance slope or a bed you would rather not touch for three years it pays for itself.

Reading your result

Four numbers, four different questions. Measured is the truth about your beds at the depth you are actually buying, and it is the one to check against your own arithmetic. With waste is that plus the allowance for ragged edges and settling, and it is what you would order if suppliers sold any quantity you asked for. The order figure is what they will actually load, rounded up to their step, and it is the number to say on the phone. Bags is the same volume expressed the way a retailer sells it, always rounded up, with the leftover printed so you know what you will be carrying back. If a top-up is active, the struck through line above is what a calculator that never asked about your existing layer would have sold you, and the gap between the two is real money. The per bed rows underneath add up exactly to the measured total, so if one looks wrong, that row is where the wrong number was typed. Everything here is a planning estimate built from your dimensions and prices you can edit, so treat it as the figure to check a quote against rather than as the quote.

Limitations

• Densities are typical dry figures with real ranges behind them. Species, grind and moisture all move them, so the weight is a band rather than a measurement. Ask your supplier what a yard of their material weighs and type it in.
• Prices are planning defaults from common US retail and they move a long way by region, season and how far you are from the yard. Put your own bag price, yard price and delivery fee into the ledger before you decide anything.
• Bale coverage for pine straw genuinely varies from 30 to 50 sq ft depending on bale size and needle length. There is no national standard bale, so confirm the figure with the seller and change the input.
• Playground depth figures are cited from the CPSC Public Playground Safety Handbook as guidance. They are not a safety certification. Verify against the specific product's documentation and your equipment's fall height.
• Regular geometry only. Curved and organic bed shapes have to be approximated by splitting them into rectangles, rings and part circles, and the more pieces you use the closer you get.
• The existing depth is whatever you measure with a finger or a trowel, and an established bed is rarely uniform. Take the depth in two or three places and use the shallower reading if you want to be sure of full coverage.
• This page sizes organic mulch, rubber mulch and pine straw. Decorative stone and river rock are sold by weight rather than volume and belong on the gravel calculator, and the soil under the mulch belongs on the topsoil calculator.

Frequently asked questions

How many bags of mulch are in a cubic yard?

13.5 bags of the standard 2 cubic foot size, or 9 bags of the 3 cubic foot size. A cubic yard is 27 cubic feet, so divide 27 by the bag size printed on the label: 1.5 cu ft bags give 18 to the yard and the 0.8 cu ft bags rubber comes in give 33.75. The 13.5 figure is the one worth remembering, because multiplying a bag price by 13.5 is the only fair way to compare it with a bulk price per yard.

How much does a cubic yard of mulch cover?

324 square feet at 1 inch deep, 162 at 2 inches, 108 at 3 inches, 81 at 4 inches and 54 at 6 inches. The formula is 324 divided by the depth in inches, which falls out of 27 cubic feet spread one inch thick. The common yard sign saying a cubic yard covers 100 square feet is true at about 3.2 inches and nowhere else, so always attach a depth to a coverage figure.

How much mulch do I need?

Multiply the bed area in square feet by the depth you are buying in inches, then divide by 324 for cubic yards or by 12 for cubic feet. The depth you are buying is the target depth minus whatever mulch is already down: for a 3 inch target over an existing 1 inch layer you buy 2 inches. A 400 square foot bed topped up 2 inches needs 66.7 cubic feet, which is 2.5 cubic yards ordered or 34 of the 2 cubic foot bags.

Is bagged or bulk mulch cheaper?

Bulk is always cheaper per cubic yard, but it comes with a delivery fee and bags do not, and that fee is the whole argument. Multiply the bag price by 13.5 for the true per yard cost: at $4.50 a bag that is $60.75 a yard against $40 for bulk. With a $75 delivery, bulk delivered only overtakes bags at about 3.6 cubic yards. If you can collect it yourself in a truck or trailer, bulk wins from the first yard. Put your own prices in the ledger, because a waived delivery moves the crossover a long way.

How much does a yard of mulch weigh?

Wood mulches run roughly 400 to 800 pounds per cubic yard dry, with shredded hardwood near 600, cedar near 500 and pine bark nuggets near 450. Rubber mulch is about 1,180. Wet material weighs 10 to 20 percent more, which matters for a trailer rating or a tonnage price and not at all for coverage. A 2 cubic foot bag of hardwood works out at about 44 pounds.

How deep should mulch be?

Two to three inches for fine shredded mulch, three to four for coarse nuggets and arborist chips whose gaps let light through, and at least three inches if you want weed suppression. Beyond four inches you start to suffocate roots and hold water against stems. Keep mulch 2 to 3 inches clear of trunks and stems in every case, because a cone of mulch piled against bark is the most common way landscaping kills a tree.

Do I need to remove old mulch before adding new?

Usually not. Organic mulch is supposed to break down into the soil, so last year's layer is doing its job and removing it wastes both the material and the benefit. Rake it loose to break up any crust, measure what is left, and buy only the difference up to your target depth. Remove it only if the bed is already at or above 4 inches, if the layer has gone matted and hydrophobic so water runs off it, or if it is visibly mouldy or diseased.

How many bales of pine straw do I need?

Divide the area in square feet by the coverage of one bale and round up. Bales cover 30 to 50 square feet each depending on bale size and needle length, with 40 a fair working default, so 800 square feet is about 20 bales. Confirm the coverage figure with your seller, because there is no standard bale and the difference between 30 and 50 is a third of your order. Pine straw settles to roughly 3 inches and wants refreshing about twice a year.

How much rubber mulch do I need for a playground?

The CPSC Public Playground Safety Handbook lists 6 inches of shredded rubber, or 9 inches of engineered wood fibre, for protection at typical residential fall heights. A 15 by 15 foot area at 225 square feet and 6 inches deep is 112.5 cubic feet, which is 4.17 cubic yards or 141 of the 0.8 cubic foot bags, roughly $1,692 and about 4,900 pounds. Treat those depths as guidance to verify against the specific product's certification and your equipment's fall height.

How many bags of mulch fit in a car or a pickup?

A 2 cubic foot bag of hardwood is about 44 pounds and takes up its own 2 cubic feet, so a sedan boot with the seats down takes six to eight bags and a half ton pickup bed takes about 27, which is two cubic yards. Payload is not the limit for mulch: at 600 pounds a yard the bed fills long before a 1,500 pound rating is reached, which is the opposite of gravel or sand. Rubber flips it back, because at 1,180 pounds a yard the payload runs out at about 1.27 yards.