Bed 1
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Sets the weight estimate.
Check the label — sizes vary by brand.
For the bags-versus-bulk comparison.
Delivered price if you know it.
This mulch calculator works out how much mulch you need in cubic yards and bags, for beds, circles, triangles and tree rings. It compares bagged against bulk pricing so you can see which is actually cheaper for your project.
The short answer
Mulch volume is area × depth ÷ 27, with depth in feet. A 30 × 6 ft bed at 3 inches deep is 180 × 0.25 ÷ 27 = 1.67 cubic yards.
There’s a shortcut worth memorising: (square feet × depth in inches) ÷ 324 = cubic yards. And one cubic yard is 13.5 bags of the standard 2 cu ft size — round up to 14.
On this page
How to use this mulch calculator
Enter your bed dimensions and depth, and the mulch calculator returns cubic yards, bag count, weight and cost. Four shapes cover garden work:
- Bed — rectangular borders, foundation plantings, vegetable beds
- Circle — round island beds and planting circles
- Tree ring — a ring with the trunk area left clear, which is how tree mulch should actually be laid
- Triangle — corner beds and wedge sections
Most yards have several beds. Use Add another bed for each one and the calculator totals them into a single order — which matters, because bulk suppliers usually have a two-yard minimum and one delivery beats three trips.
The tree ring mode is worth using rather than treating a tree as a plain circle. It subtracts the clear zone around the trunk, so you don’t order mulch for an area that should stay bare. Why that matters is covered below.
The mulch calculator formula
Cubic yards = Length (ft) × Width (ft) × Depth (ft) ÷ 27
Or the shortcut, working straight from inches:
Cubic yards = (Area in ft² × Depth in inches) ÷ 324
The 324 works because 27 cubic feet per yard × 12 inches per foot = 324. It saves converting depth to feet, and it’s the version most landscapers use in their heads.
Worked example — 30 × 6 ft border at 3 inches
Bulk suppliers typically sell in half-yard increments with a two-yard minimum, so this job rounds to 2 yards either way.
How many bags of mulch are in a cubic yard?
A cubic yard is 27 cubic feet, so the bag count is 27 divided by the bag size. The catch is that bag size varies by product and retailer, and the number printed on the bag is the only one that counts.
| Bag size | Bags per yd³ | Buy | Commonly used for |
|---|---|---|---|
| 0.8 cu ft | 33.75 | 34 | Rubber mulch |
| 1 cu ft | 27 | 27 | Specialty and soil amendments |
| 1.5 cu ft | 18 | 18 | Dyed and premium mulch |
| 2 cu ft | 13.5 | 14 | The standard size at most big-box stores |
| 3 cu ft | 9 | 9 | Cedar and bulk hardwood |
A 1.5 cu ft bag at $4 is not cheaper than a 2 cu ft bag at $5 — it’s 25% less mulch for 20% less money. Retailers frequently promote the smaller size, so compare on price per cubic foot rather than price per bag. At the extreme, covering a yard costs 18 bags of the small size against 9 of the 3 cu ft size.
A full pallet is typically 70 bags at 2 cu ft or 80 bags at 1.5 cu ft — roughly 5.2 and 4.4 cubic yards respectively. If your project needs a pallet or more, bulk delivery is almost certainly cheaper and saves you handling 70 individual bags.
How much does a yard of mulch cover?
| Depth | Per cubic yard | Per 2 cu ft bag | yd³ per 100 ft² |
|---|---|---|---|
| 1 inch | 324 ft² | 24 ft² | 0.31 |
| 2 inches | 162 ft² | 12 ft² | 0.62 |
| 3 inches | 108 ft² | 8 ft² | 0.93 |
| 4 inches | 81 ft² | 6 ft² | 1.24 |
How deep should mulch be?
Two to three inches is the general recommendation, and the right figure within that range depends on how coarse the material is.
| Situation | Depth | Reason |
|---|---|---|
| Fine mulch — triple-ground, fine bark | 2 in | Fine material packs tight; deeper restricts air and water |
| Coarse mulch — wood chips, chunky bark | 3–4 in | Loose structure needs depth to block light |
| Established beds, annual refresh | 1–2 in | Topping up what has decomposed |
| New beds with heavy weed pressure | 3–4 in | Blocking germination |
| Around shallow-rooted shrubs | 2 in | Azaleas and rhododendrons resent deep mulch |
| Vegetable beds | 1–2 in | Soil needs to warm in spring |
Before adding a fresh layer, check what’s already there. Mulch decomposes slowly, and beds that get topped up every spring can build to six inches or more over a few years. If existing mulch is already 2 inches deep, rake it to loosen and break the crust rather than burying it under more.
Beyond about 4 inches, mulch starts working against you. It holds water against stems and crowns, which invites rot. It restricts oxygen to roots. And thick fine mulch can form a hydrophobic crust that sheds rainfall instead of letting it through — the bed ends up drier than if you had used none.
The mulch volcano — and why the tree ring mode exists
Piling mulch against a tree trunk in a cone is one of the most common and most damaging landscaping mistakes. Bark above the root flare is not adapted to constant moisture. Kept damp, it stays soft, invites decay fungi and gives rodents cover to chew the bark right through. Trees can also send roots up into the mulch, which then circle the trunk and eventually strangle it — years after the mulch was applied.
Mulch should be laid like a doughnut, not a volcano:
- Keep it clear of the trunk. Leave several inches of bare ground so the root flare — where the trunk widens at the base — stays visible.
- Spread wide rather than deep. Wider is better for the tree. Extending toward the drip line gives the roots far more benefit than piling depth at the trunk.
- Keep to 2–3 inches across the ring, the same as any other bed.
The tree ring mode in the calculator asks for the clear diameter at the trunk and subtracts it, so your order reflects the ring you should actually be laying.
Mulch types compared
| Type | lb/yd³ dry | Strengths | Drawbacks |
|---|---|---|---|
| Shredded hardwood | ~600 | Knits together, stays put on slopes, cheap | Can mat and crust; fades in a season |
| Pine bark | ~500 | Slow to break down, good color, acidifies slightly | Nuggets float and wash away in heavy rain |
| Wood chips | ~675 | Coarse, long lasting, often free from arborists | Rough appearance; not for formal beds |
| Cedar | ~450 | Aromatic, slow to decay, deters some insects | Costs more; color greys quickly |
| Cypress | ~500 | Durable, resists floating | Sourcing raises real sustainability concerns |
| Dyed mulch | ~600 | Holds color a full season | Often ground pallet wood; check the source |
| Compost | ~1,100 | Feeds soil as it breaks down | Poor weed suppression; weeds germinate in it |
| Rubber mulch | ~1,200 | Doesn’t decompose, used under play equipment | Adds nothing to soil, heats up, hard to remove later |
Weight matters more than it first appears. A cubic yard of wood mulch is 400–800 lb dry — light enough for a half-ton pickup. After heavy rain the same yard can exceed 1,000 lb. Compost and rubber are heavier again, and a yard of either is approaching the payload limit of a small truck on its own.
Bags or bulk?
Under 2 yd³
Buy bags
About 27 bags or fewer. Most bulk suppliers have a two-yard minimum plus a delivery fee, which wipes out the per-yard saving on small jobs.
2–3 yd³
Run the numbers
This is the crossover. Compare bag price × count against bulk price plus delivery — the calculator does it if you enter both prices.
Over 3 yd³
Order bulk
Bulk typically runs $25–$45 per yard delivered against $60–$80 per yard in bags. Above a pallet, bulk wins on price and on not handling 70 bags.
Bulk has one non-price advantage worth knowing: it’s usually fresher. Bagged mulch can sit on a pallet for months, and mulch stored damp in plastic can go anaerobic — “sour mulch” that smells of vinegar or ammonia and can scorch plants. If a bag smells sharp when opened, spread it out to air for a day before using it.
When to mulch
Mid to late spring, once the soil has warmed. Mulching too early on cold soil insulates it and delays root growth just as plants are starting into season. In practice, wait until soil temperatures have come up and perennials are visibly emerging, so you can see what you’re working around.
A second, lighter application in late autumn helps insulate roots through winter freeze-thaw cycles, particularly for anything marginally hardy in your zone. That’s a protective layer, not a full refresh — an inch or two is plenty.
On buying: spring, roughly mid-March through May, is when retailers run the deepest bag promotions and pallet pricing. Autumn brings a second discount window on remaining stock. Bags bought in winter and stored outdoors absorb water, which makes them heavier to carry and no more useful.
Mulch mistakes to avoid
- Piling it against trunks and stems. The mulch volcano rots bark and invites rodents.
- Going deeper than 4 inches. It restricts oxygen and can shed water rather than absorb it.
- Adding a full layer over existing mulch every year. Check the depth first and rake to break the crust.
- Comparing bag prices without checking bag size. 1.5 and 2 cu ft bags look nearly identical on a shelf.
- Using compost as a weed barrier. Weeds germinate happily in it.
- Laying plastic sheeting underneath. It blocks air and water to the soil, and weeds root in the mulch on top anyway.
- Mulching too early in spring and keeping the soil cold.
Frequently asked questions
How much mulch do I need?
Multiply your bed area in square feet by the depth in inches and divide by 324 to get cubic yards. A 180 ft² bed at 3 inches needs 1.67 cubic yards, which is 45 cubic feet or 23 bags of the standard 2 cu ft size.
How many bags of mulch are in a cubic yard?
13.5 bags of the standard 2 cu ft size, rounded up to 14. For other sizes it’s 9 bags of 3 cu ft, 18 bags of 1.5 cu ft, 27 bags of 1 cu ft, or 34 bags of 0.8 cu ft. Always check the volume printed on the bag.
How much area does a bag of mulch cover?
A 2 cu ft bag covers about 8 square feet at 3 inches deep, 12 ft² at 2 inches, or 24 ft² at 1 inch. A 3 cu ft bag covers 12 ft² at 3 inches.
How deep should mulch be?
Two to three inches for most beds. Use 2 inches for fine, finely ground mulch which packs tightly, and 3–4 inches for coarse wood chips or chunky bark. Never exceed about 4 inches — deeper restricts oxygen to roots and can shed rainfall instead of letting it soak in.
How much does a yard of mulch weigh?
400 to 800 pounds dry for wood mulch, depending on type and moisture. After heavy rain the same yard can top 1,000 pounds. Compost and rubber mulch are heavier, around 1,100 to 1,200 pounds per cubic yard.
Is it cheaper to buy mulch in bags or bulk?
Bulk is typically $25–$45 per cubic yard delivered, against roughly $60–$80 per yard in bags. But most bulk suppliers have a two-yard minimum and charge for delivery, so bags usually win under about 2 cubic yards. The crossover is generally between 2 and 3 yards.
How much mulch fits in a pickup truck?
An 8 ft bed holds roughly 2.5 cubic yards level. Since dry wood mulch is only 400–800 lb per yard, weight is rarely the limit — unlike gravel or soil. Wet mulch is heavier, and compost or rubber at over 1,000 lb per yard will reach a half-ton payload limit at around one yard.
Should I remove old mulch before adding new?
Usually not. Old mulch breaks down into the soil and adds organic matter. Check the existing depth first — if it’s already 2 inches or more, just rake it to break up any crust rather than adding a full new layer. Remove it only if it has matted badly or smells sour.
Can you put mulch right against a tree trunk?
No. Mulch piled against a trunk keeps bark permanently damp, which invites decay and gives rodents cover to gnaw through it. Leave several inches of bare ground so the root flare stays visible, and spread the mulch wide rather than deep — extending toward the drip line benefits the tree far more.
When is the best time to put down mulch?
Mid to late spring, once the soil has warmed and perennials are visibly emerging. Mulching too early insulates cold soil and delays root growth. A lighter second layer in late autumn helps protect roots through winter freeze-thaw cycles.
Do I need landscape fabric under mulch?
Generally no, and plastic sheeting is worse than useless — it blocks air and water reaching the soil. Weeds germinate in the mulch layer on top of fabric anyway, and the fabric makes future planting awkward. A proper 3 inch mulch layer suppresses weeds well enough on its own.
Can I use this mulch calculator in metric?
Yes. Switch the header toggle to m / mm and enter dimensions in metres and millimetres. Results show cubic yards, cubic metres and bag counts together.
Sources and method
- Bag volumes reflect standard US retail sizes; the figure printed on each bag is authoritative
- Depth and application guidance follows published university extension recommendations on mulching practice
- Weight ranges compiled from multiple landscape supply references; moisture content causes wide variation
- Pricing ranges are indicative US figures and vary substantially by region and season
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How this mulch calculator works out its numbers
Volume uses standard geometric formulas with all inputs normalised to feet, then divided by 27 for cubic yards. Tree ring mode calculates an annulus — the outer circle area minus the clear trunk circle — so mulch isn’t ordered for ground that should stay bare. Bag counts divide total cubic feet by the selected bag volume and round up, since partial bags don’t exist at retail. Bulk quantities round up to the nearest half yard, which is how most suppliers sell.
Weight figures are dry values and will be materially higher after rain — wood mulch can gain 25% or more in weight without gaining any volume. Pallet counts assume 70 bags at 2 cu ft.
Pricing comparisons use the bag and bulk prices you enter, so they reflect your local suppliers. Bulk delivery fees and minimum-order rules are not included and can change which option is cheaper on smaller jobs.